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Plant Sex Gets Hot

Plant Sex Gets Hot | PlantBioInnovation | Scoop.it
Sex is not just an activity confined to higher animals such as mammals and not just for reproduction.
Biswapriya Biswavas Misra's insight:

Sex is not just an activity confined to higher animals such as mammals and not just for reproduction. The changes in offspring that result during reproduction are integral to the continuing adaptation and evolution of millions of species of plants, fungi and other organisms throughout the food chain. 

Without such genetic shuffling, life wouldn't have adapted to the planet's frequently changing climates, or to new pests, parasites and predators. Our environment is always changing and emerging pressures, such as predicted rises in temperature for example, could threaten food production systems by affecting overall yield – it has been estimated that a 1°C rise in night-time temperature could reduce rice yields by about 10%. Don't panic about your coffee, despite the doomsday scenarios you read in mainstream media, other species of coffee will be suited for whatever conditions arise, but what about other plants that have not been artificially selected by mankind for agriculture?

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PlantBioInnovation
Discovery and Invention Aspects of Plant Biology That Are Interesting, Innovative and Novel !
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MPMI: Transcriptome Sequencing Uncovers the Avr...

MPMI: Transcriptome Sequencing Uncovers the Avr... | PlantBioInnovation | Scoop.it
The Cf-5 gene of tomato confers resistance to strains of the fungal pathogen Cladosporium fulvum carrying the avirulence gene Avr5. Although Cf-5 has been cloned, Avr5 has remained elusive.
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Nitrogen and water availability to tomato plants triggers bottom-up effects on the leafminer Tuta absoluta

Nitrogen and water availability to tomato plants triggers bottom-up effects on the leafminer Tuta absoluta | PlantBioInnovation | Scoop.it
This study examined the effects of various levels of nitrogen inputs (optimal, insufficient and excessive) and water inputs (optimal, low drought and high drought) to tomato plants (Solanum lycopersicum) on survival and development of an invasive tomato leafminer, Tuta absoluta (Meytick) (Lepidoptera: Gelechiidae). Plant growth i.e. plant height and the number of nodes declined under insufficient or excessive nitrogen treatment. Compared to optimal N, insufficient N treatment decreased leaf N content and increased the carbon/nitrogen ratio (C/N) whereas an excess of N had no effect on both leaf N content and leaf C/N ratio. Sub-optimal nitrogen supplies, water treatments and their interactions, significantly reduced the leafminer survival rate and slowed down its development. Together with the findings from three recent companion studies, we assumed that a combination of changes in nutritional value and chemical defense could explain these observed effects. Furthermore, our findings supported both the “Plant vigor hypothesis” and the “Nitrogen limitation hypothesis”.
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Disruption of Mediator rescues the stunted growth of a lignin-deficient Arabidopsis mutant

Disruption of Mediator rescues the stunted growth of a lignin-deficient Arabidopsis mutant | PlantBioInnovation | Scoop.it
Lignin is a phenylpropanoid-derived heteropolymer important for the strength and rigidity of the plant secondary cell wall. Genetic disruption of lignin biosynthesis has been proposed as a means to improve forage and bioenergy crops, but frequently results in stunted growth and developmental abnormalities, the mechanisms of which are poorly understood. Here we show that the phenotype of a lignin-deficient Arabidopsis mutant is dependent on the transcriptional co-regulatory complex, Mediator. Disruption of the Mediator complex subunits MED5a (also known as REF4) and MED5b (also known as RFR1) rescues the stunted growth, lignin deficiency and widespread changes in gene expression seen in the phenylpropanoid pathway mutant ref8, without restoring the synthesis of guaiacyl and syringyl lignin subunits. Cell walls of rescued med5a/5b ref8 plants instead contain a novel lignin consisting almost exclusively of p-hydroxyphenyl lignin subunits, and moreover exhibit substantially facilitated polysaccharide saccharification. These results demonstrate that guaiacyl and syringyl lignin subunits are largely dispensable for normal growth and development, implicate Mediator in an active transcriptional process responsible for dwarfing and inhibition of lignin biosynthesis, and suggest that the transcription machinery and signalling pathways responding to cell wall defects may be important targets to include in efforts to reduce biomass recalcitrance.
Biswapriya Biswavas Misra's insight:

Lignin is a phenylpropanoid-derived heteropolymer important for the strength and rigidity of the plant secondary cell wall1, 2. Genetic disruption of lignin biosynthesis has been proposed as a means to improve forage and bioenergy crops, but frequently results in stunted growth and developmental abnormalities, the mechanisms of which are poorly understood3. Here we show that the phenotype of a lignin-deficient Arabidopsis mutant is dependent on the transcriptional co-regulatory complex, Mediator. Disruption of the Mediator complex subunits MED5a (also known as REF4) and MED5b (also known as RFR1) rescues the stunted growth, lignin deficiency and widespread changes in gene expression seen in the phenylpropanoid pathway mutant ref8, without restoring the synthesis of guaiacyl and syringyl lignin subunits. Cell walls of rescued med5a/5b ref8 plants instead contain a novel lignin consisting almost exclusively of p-hydroxyphenyl lignin subunits, and moreover exhibit substantially facilitated polysaccharide saccharification. These results demonstrate that guaiacyl and syringyl lignin subunits are largely dispensable for normal growth and development, implicate Mediator in an active transcriptional process responsible for dwarfing and inhibition of lignin biosynthesis, and suggest that the transcription machinery and signalling pathways responding to cell wall defects may be important targets to include in efforts to reduce biomass recalcitrance.

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A comprehensive evaluation of assembly scaffolding tools

Genome assembly is typically a two-stage process: contig assembly followed by the use of paired sequencing reads to join contigs into scaffolds. Scaffolds are usually the focus of reported assembly statistics; longer scaffolds greatly facilitate the use of genome sequences in downstream analyses, and it is appealing to present larger numbers as metrics of assembly performance. However, scaffolds are highly prone to errors, especially when generated using short reads, which can directly result in inflated assembly statistics.
Biswapriya Biswavas Misra's insight:
Abstract (provisional)Background

Genome assembly is typically a two-stage process: contig assembly followed by the use of paired sequencing reads to join contigs into scaffolds. Scaffolds are usually the focus of reported assembly statistics; longer scaffolds greatly facilitate the use of genome sequences in downstream analyses, and it is appealing to present larger numbers as metrics of assembly performance. However, scaffolds are highly prone to errors, especially when generated using short reads, which can directly result in inflated assembly statistics.

Results

Here we provide the first independent evaluation of scaffolding tools for second-generation sequencing data. We find large variations in the quality of results depending on the tool and dataset used. Even extremely simple test cases of perfect input, constructed to elucidate the behavior of each algorithm, produced some surprising results. We further dissect the performance of the scaffolders using real and simulated sequencing data derived from the genomes of Staphylococcus aureus, Rhodobacter sphaeroides, Plasmodium falciparum and Homo sapiens. The results from simulated data are of high quality, with several of the tools producing perfect output. However, at least 10% of joins remains unidentified when using real data.

Conclusions

The scaffolders vary in their usability, speed and number of correct and missed joins made between contigs. Results from real data highlight opportunities for further improvements of the tools. Overall, SGA, SOPRA and SSPACE generally outperform the other tools on our datasets. However, the quality of the results is highly dependent on the read mapper and genome complexity.

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The effect of temperature on reproduction in the summer and winter annual Arabidopsis thaliana ecotypes Bur and Cvi

The effect of temperature on reproduction in the summer and winter annual Arabidopsis thaliana ecotypes Bur and Cvi | PlantBioInnovation | Scoop.it
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Abstract

Background and Aims Seed yield and dormancy status are key components of species fitness that are influenced by the maternal environment, in particular temperature. Responses to environmental conditions can differ between ecotypes of the same species. Therefore, to investigate the effect of maternal environment on seed production, this study compared two contrasting Arabidopsis thaliana ecotypes, Cape Verdi Isle (Cvi) and Burren (Bur). Cvi is adapted to a hot dry climate and Bur to a cool damp climate, and they exhibit winter and summer annual phenotypes, respectively.

Methods Bur and Cvi plants were grown in reciprocal controlled environments that simulated their native environments. Reproductive development, seed production and subsequent germination behaviour were investigated. Measurements included: pollen viability, the development of floral structure, and germination at 10 and 25 °C in the light to determine dormancy status. Floral development was further investigated by applying gibberellins (GAs) to alter the pistil:stamen ratio.

Key Results Temperature during seed development determined seed dormancy status. In addition, seed yield was greatly reduced by higher temperature, especially in Bur (>90 %) compared with Cvi (approx. 50 %). The reproductive organs (i.e. stamens) of Bur plants were very sensitive to high temperature during early flowering. Viability of pollen was unaffected, but limited filament extension relative to that of the pistils resulted in failure to pollinate. Thus GA applied to flowers to enhance filament extension largely overcame the effect of high temperature on yield.

Conclusions High temperature in the maternal environment reduced dormancy and negatively affected the final seed yield of both ecotypes; however, the extent of these responses differed, demonstrating natural variation. Reduced seed yield in Bur resulted from altered floral development not reduced pollen viability. Future higher temperatures will impact on seed performance, but the consequences may differ significantly between ecotypes of the same species.

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The wheat powdery mildew genome shows the unique evolution of an obligate biotroph

The wheat powdery mildew genome shows the unique evolution of an obligate biotroph | PlantBioInnovation | Scoop.it
Thomas Wicker and colleagues report the whole-genome sequencing of four wheat powdery mildew (Blumeria graminis forma specialis tritici) isolates from different geographic regions. Their comparative genomic analysis provides insights into the evolution of powdery mildews, which are obligate biotropic fungal pathogens.
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Wheat powdery mildew, Blumeria graminis forma specialis tritici, is a devastating fungal pathogen with a poorly understood evolutionary history. Here we report the draft genome sequence of wheat powdery mildew, the resequencing of three additional isolates from different geographic regions and comparative analyses with the barley powdery mildew genome. Our comparative genomic analyses identified 602 candidate effector genes, with many showing evidence of positive selection. We characterize patterns of genetic diversity and suggest that mildew genomes are mosaics of ancient haplogroups that existed before wheat domestication. The patterns of diversity in modern isolates suggest that there was no pronounced loss of genetic diversity upon formation of the new host bread wheat 10,000 years ago. We conclude that the ready adaptation of B. graminis f.sp. tritici to the new host species was based on a diverse haplotype pool that provided great genetic potential for pathogen variation.

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Side-Chain Modification of Cytokinins Controls Shoot Growth in Arabidopsis

Side-Chain Modification of Cytokinins Controls Shoot Growth in Arabidopsis | PlantBioInnovation | Scoop.it

Via David Gifford
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David Gifford's curator insight, February 27, 11:55 PM

Side-Chain Modification of Cytokinin defines the Function

A research group at the RIKEN CSRS revealed that the function of the plant hormone cytokinin depends not only on changes in quantity but also in quality, which is generated by side-chain modification of cytokinins.

 http://www.csrs.riken.jp/en/press/press131126.html

 

also RIKEN Research Magazine http://www.rikenresearch.riken.jp/eng/research/7635 ;

"Many ways to grow" 24 January 2014

 

Cytokinins, a class of plant hormones, are central regulators of plant growth and development. The group was searching for enzyme genes responsible for making the side-chain modifications to synthesize trans-zeatin (tZ)-type cytokinins. They succeeded in identifying CYP735A1 and CYP735A2 as such genes. Analysis of a mutant of CYP735A activity, which is deficient in tZ-type cytokinins, revealed that the tZ-type cytokinins promote shoot growth, whereas cytokinins without sid- chain modification do not. These results show that the side-chain modification of cytokinin is crucial for shoot growth regulation in plants.

 

Elucidation of this new mechanism is expected to pave the way for development of novel technologies to increase crop harvests and biomass production.

 <Contact>
Hitoshi Sakakibara: Group Director
Takatoshi Kiba: Research Scientist
Plant Productivity Systems Research Group

 

Some quotes from the paper

- "Although the major site of tZ-type CK biosynthesis is in the root vasculature ( Figure S5), the grafting experiments showed that root-borne tZ-type CKs are not necessarily required for normal shoot growth. Thus, the role of root-borne tZ-type CKs might be to stimulate shoot growth when roots sense favorable conditions."

- " A supply of a nitrogen source, for example nitrate, might be an example of such a situation. In this scenario, nitrate would trigger iP-type CK biosynthesis though the induction of IPT3 (Miyawaki et al., 2004 and Takei et al., 2004a), followed by CK-mediated upregulation of the expression of theCYP735As ( Takei et al., 2004b), finally leading to tZ-type CK accumulation in the root vasculature and transport to the shoot via the xylem." 

-" By exploiting the first mutant impaired in CK side-chain modification, our study demonstrated that trans-hydroxylation of CK is a specific signal that facilitates growth in the shoot of Arabidopsis. The existence of CYP735A orthologs throughout the seed plants suggests that the signaling role of trans-hydroxylation might be highly conserved ( Mizutani and Ohta, 2010 and Nelson and Werck-Reichhart, 2011). Consistent with this idea, CK receptors with high affinity to tZ are found in maize ( Lomin et al., 2011 and Yonekura-Sakakibara et al., 2004). Thus,CYP735A appears a promising target for crop improvement because shoot growth enhancement could be achieved by increasing the expression of this gene without reducing root growth."

 

Figure 7. 

Recovery of cyp735a1 cyp735a2 Shoot Growth by Root-Borne tZ-Type Cytokinins

(A and B) Three-day-old wild-type (Col-0) and a1-2 a2-1 (cypDM) were grafted reciprocally by the wedge-grafting method and pictures were taken 38 days (A) and 58 days (B) after grafting.

(C) Cytokinin concentrations in rosette leaves (scions) of grafted plants at 45 days after germination. Error bars represent SD of four biological replicates. The concentration of each cytokinin species is shown in Table S5. gFW, gram fresh weight. Scale bar: 2 cm.

 

Original Paper

Developmental Cell, Vol 27, pp652-461 (2013), doi.org/10.1016/j.devcel.2013.10.004
T. Kiba, K. Takei, M. Kojima, H. Sakakibara,
" Side-chain Modification of Cytokinins Control Shoot Growth in Arabidopsis".

http://www.sciencedirect.com/science/article/pii/S1534580713006011#

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Volume 16, Plant Breeding Reviews: Jules Janick

Volume 16, Plant Breeding Reviews [Jules Janick] on Amazon.com. *FREE* shipping on qualifying offers.
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Auxin Overproduction in Shoots Cannot Rescue Auxin Deficiencies in Arabidopsis Roots

Auxin Overproduction in Shoots Cannot Rescue Auxin Deficiencies in Arabidopsis Roots | PlantBioInnovation | Scoop.it
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Auxin plays an essential role in root development. It has been a long-held dogma that auxin required for root development is mainly transported from shoots into roots by polarly localized auxin transporters. However, it is known that auxin is also synthesized in roots. Here we demonstrate that a group of YUCCA (YUC) genes, which encode the rate-limiting enzymes for auxin biosynthesis, plays an essential role in Arabidopsis root development. Five YUC genes (YUC3, 5, 7, 8, 9) display distinct expression patterns during root development. Simultaneous inactivation of the five YUC genes (yucQ mutants) leads to the development of very short and agravitropic primary roots. The yucQ phenotypes are rescued by either adding 5 nM of the natural auxin, indole-3-acetic acid (IAA), in the growth media or by expressing a YUC gene in the roots of yucQ. Interestingly, overexpression of a YUC gene in shoots in yucQ causes the characteristic auxin overproduction phenotypes in shoots, however, the root defects of yucQ are not rescued. Our data demonstrate that localized auxin biosynthesis in roots is required for normal root development and that auxin transported from shoots is not sufficient for supporting root elongation and root gravitropic responses.

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MPMI: Metabolic Environments and Genomic Features Associated with Pathogenic and Mutualistic Interactions between Bacteria and Plants

MPMI: Metabolic Environments and Genomic Features Associated with Pathogenic and Mutualistic Interactions between Bacteria and Plants | PlantBioInnovation | Scoop.it

Genomic characteristics discriminating parasitic and mutualistic relationship of bacterial symbionts with plants are poorly understood. This study comparatively analysed the genomes of 54 mutualists and pathogens to discover genomic markers associated with the different phenotypes. Using metabolic network models we predict external environments associated with free living and symbiotic lifestyles and quantify dependences of symbionts on the host in terms of the consumed metabolites. We show that specific differences between the phenotypes are pronounced at the levels of metabolic enzymes, especially carbohydrate active, and protein functions. Overall, biosynthetic functions are enriched and more diverse in plant mutualists while processes and functions involved in degradation and host invasion are enriched and more diverse in pathogens. A distinctive characteristic of plant pathogens is a putative novel secretion system with a circadian rhythm regulator. A specific marker of plant mutualists is the co-residence of genes encoding nitrogenase and Ribulose Bisphosphate Carboxylase/Oxygenase (RuBisCO). We predict that RuBisCO is likely used in a putative metabolic pathway to supplement carbon obtained heterotrophically with low-cost assimilation of carbon from CO2. We validate results of the comparative analysis by predicting correct phenotype, pathogenic or mutualistic, for 20 symbionts in an independent set of 30 pathogens, mutualists, and commensals.


Via Stéphane Hacquard, Francis Martin
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Biotechnology and Plant Breeding: Applications and Approaches for Developing Improved Cultivars: Aluízio Borém, Roberto Fritsche-Neto:

Biotechnology and Plant Breeding: Applications and Approaches for Developing Improved Cultivars [Aluízio Borém, Roberto Fritsche-Neto] on Amazon.com. *FREE* shipping on qualifying offers.
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Sequence and 3D structure based analysis of TNT degrading proteins in Arabidopsis thaliana

Sequence and 3D structure based analysis of TNT degrading proteins in Arabidopsis thaliana | PlantBioInnovation | Scoop.it
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Functional redundancy arises between gene paralogs as well as non-homologous genes that play a common role at a shared node. The bHLH transcription factor FAMA, along with the paralogous MYB genes, FOUR LIPS (FLP) and MYB88 all ensure that Arabidopsis stomata contain just two guard cells (GCs) by enforcing a single symmetric precursor cell division before stomatal mature. Consistent with this function, FLP and FAMA exhibit the same expression pattern in which both translational GFP fusions emit fluorescence just before and after symmetric division. However, FAMA but not FLP is required to confer GC fate (Ohashi-Ito and Bergmann, 2006). Strikingly, swapping the genes and promoters of the FLP and FAMA genes results in the reciprocal complementation of respective loss of function mutants. Thus, a FLP transgene can restore GC fate to a fama mutant background. FAMA, FLP, and the FLP paralog MYB88 were previously shown to influence higher order functions in stomatal development including maintaining and stabilizing stomatal fate. Here we show that these overlapping functions likely also involve interactions between FLP and FAMA with the RETINOBLASTOMA-RELATED (RBR) protein.

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Tryptophan-dependent auxin biosynthesis is required for HD-ZIP III-mediated xylem patterning

Tryptophan-dependent auxin biosynthesis is required for HD-ZIP III-mediated xylem patterning | PlantBioInnovation | Scoop.it
Biswapriya Biswavas Misra's insight:

The development and growth of higher plants is highly dependent on the conduction of water and minerals throughout the plant by xylem vessels. In Arabidopsis roots the xylem is organized as an axis of cell files with two distinct cell fates: the central metaxylem and the peripheral protoxylem. During vascular development, high and low expression levels of the class III HD-ZIP transcription factors promote metaxylem and protoxylem identities, respectively. Protoxylem specification is determined by both mobile, ground tissue-emanating miRNA165/6 species, which downregulate, and auxin concentrated by polar transport, which promotes HD-ZIP III expression. However, the factors promoting high HD-ZIP III expression for metaxylem identity have remained elusive. We show here that auxin biosynthesis promotes HD-ZIP III expression and metaxylem specification. Several auxin biosynthesis genes are expressed in the outer layers surrounding the vascular tissue in Arabidopsis root and downregulation of HD-ZIP III expression accompanied by specific defects in metaxylem development is seen in auxin biosynthesis mutants, such as trp2-12, wei8 tar2 or a quintuple yucca mutant, and in plants treated with L-kynurenine, a pharmacological inhibitor of auxin biosynthesis. Some of the patterning defects can be suppressed by synthetically elevated HD-ZIP III expression. Taken together, our results indicate that polar auxin transport, which was earlier shown to be required for protoxylem formation, is not sufficient to establish a proper xylem axis but that root-based auxin biosynthesis is additionally required.

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Green Light Synergistally Enhances Male Sweetpotato Weevil Response to Sex Pheromone

Green Light Synergistally Enhances Male Sweetpotato Weevil Response to Sex Pheromone | PlantBioInnovation | Scoop.it
Sweetpotato, commercially grown in over 100 countries, is one of the ten most important staple crops in the world. Sweetpotato weevil is a major pest of sweetpotato in most areas of cultivation, the feeding of which induces production in the sweetpotato root of extremely bitter tasting and toxic sesquiterpenes which can render the sweetpotato unfit for consumption. A significant step towards improved management of this weevil species was the identification of a female-produced sex pheromone [lsqb](Z)-3-dodecenyl (E)-2-butenoate[rsqb] to which males are highly attracted. Reported here are results of research that documents a nearly 5-fold increase in male sweetpotato weevil catch in traps baited with this pheromone and a green light provided by a solar-powered, light-emitting diode (LED). The combination of olfactory and night-visible visual cues significantly enhanced trap effectiveness for this nighttime-active insect species. These results provide promise for improved sweetpotato weevil detection and suppression in mass trapping programs.
Biswapriya Biswavas Misra's insight:

Sweetpotato, commercially grown in over 100 countries, is one of the ten most important staple crops in the world. Sweetpotato weevil is a major pest of sweetpotato in most areas of cultivation, the feeding of which induces production in the sweetpotato root of extremely bitter tasting and toxic sesquiterpenes which can render the sweetpotato unfit for consumption. A significant step towards improved management of this weevil species was the identification of a female-produced sex pheromone [(Z)-3-dodecenyl (E)-2-butenoate] to which males are highly attracted. Reported here are results of research that documents a nearly 5-fold increase in male sweetpotato weevil catch in traps baited with this pheromone and a green light provided by a solar-powered, light-emitting diode (LED). The combination of olfactory and night-visible visual cues significantly enhanced trap effectiveness for this nighttime-active insect species. These results provide promise for improved sweetpotato weevil detection and suppression in mass trapping programs.

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Pollen sensitivity to ultraviolet-B (UV-B) suggests floral structure evolution in alpine plants

Pollen sensitivity to ultraviolet-B (UV-B) suggests floral structure evolution in alpine plants | PlantBioInnovation | Scoop.it
Various biotic and abiotic factors are known to exert selection pressures on floral traits, but the influence of ultraviolet-B (UV-B) light on the evolution of flower structure remains relatively unexplored. We have examined the effectiveness of flower structure in blocking radiation and the effects of UV-B on pollen viability in 42 species of alpine plants in the Hengduan Mountains, China. Floral forms were categorized as either protecting or exposing pollen grains to UV-B. The floral materials of plants with exposed and protected pollen grains were able to block UV-B at similar levels. Exposure to UV-B radiation in vitro resulted in a significantly greater loss of viability in pollen from plant species with protective floral structures. The pronounced sensitivity of protected pollen to UV-B radiation was associated with the type of flower structure. These findings demonstrate that UV-B plays an important role in the evolution of protective floral forms in alpine plants.
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Nectar secretion requires sucrose phosphate synthases and the sugar transporter SWEET9

Nectar secretion requires sucrose phosphate synthases and the sugar transporter SWEET9 | PlantBioInnovation | Scoop.it
Angiosperms developed floral nectaries that reward pollinating insects. Although nectar function and composition have been characterized, the mechanism of nectar secretion has remained unclear. Here we identify SWEET9 as a nectary-specific sugar transporter in three eudicot species: Arabidopsis thaliana, Brassica rapa (extrastaminal nectaries) and Nicotiana attenuata (gynoecial nectaries). We show that SWEET9 is essential for nectar production and can function as an efflux transporter. We also show that sucrose phosphate synthase genes, encoding key enzymes for sucrose biosynthesis, are highly expressed in nectaries and that their expression is also essential for nectar secretion. Together these data are consistent with a model in which sucrose is synthesized in the nectary parenchyma and subsequently secreted into the extracellular space via SWEET9, where sucrose is hydrolysed by an apoplasmic invertase to produce a mixture of sucrose, glucose and fructose. The recruitment of SWEET9 for sucrose export may have been a key innovation, and could have coincided with the evolution of core eudicots and contributed to the evolution of nectar secretion to reward pollinators.
Biswapriya Biswavas Misra's insight:

Angiosperms developed floral nectaries that reward pollinating insects1. Although nectar function and composition have been characterized, the mechanism of nectar secretion has remained unclear2. Here we identify SWEET9 as a nectary-specific sugar transporter in three eudicot species: Arabidopsis thaliana, Brassica rapa (extrastaminal nectaries) and Nicotiana attenuata (gynoecial nectaries). We show that SWEET9 is essential for nectar production and can function as an efflux transporter. We also show that sucrose phosphate synthase genes, encoding key enzymes for sucrose biosynthesis, are highly expressed in nectaries and that their expression is also essential for nectar secretion. Together these data are consistent with a model in which sucrose is synthesized in the nectary parenchyma and subsequently secreted into the extracellular space via SWEET9, where sucrose is hydrolysed by an apoplasmic invertase to produce a mixture of sucrose, glucose and fructose. The recruitment of SWEET9 for sucrose export may have been a key innovation, and could have coincided with the evolution of core eudicots and contributed to the evolution of nectar secretion to reward pollinators.

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A Proteomic Approach of Bradyrhizobium/Aeschynomene Root and Stem Symbioses Reveals the Importance of the fixA Locus for Symbiosis

A Proteomic Approach of Bradyrhizobium/Aeschynomene Root and Stem Symbioses Reveals the Importance of the fixA Locus for Symbiosis | PlantBioInnovation | Scoop.it
Rhizobia are soil bacteria that are able to form symbiosis with plant hosts of the legume family. These associations result in the formation of organs, called nodules in which bacteria fix atmospheric nitrogen to the benefit of the plant. Most of our knowledge on the metabolism and the physiology of the bacteria during symbiosis derives from studying roots nodules of terrestrial plants. Here we used a proteomics approach to investigate the bacterial physiology of photosynthetic Bradyrhizobium sp. ORS278 during the symbiotic process with the semi aquatical plant Aeschynomene indica that forms root and stem nodules. We analyzed the proteomes of bacteria extracted from each type of nodule. First, we analyzed the bacteroid proteome at two different time points and found only minor variation between the bacterial proteomes of 2-week- and 3-week-old nodules. High conservation of the bacteroid proteome was also found when comparing stem nodules and root nodules. Among the stem nodule specific proteins were those related to the phototrophic ability of Bradyrhizobium sp. ORS278. Furthermore, we compared our data with those obtained during an extensive genetic screen previously published. The symbiotic role of four candidate genes which corresponding proteins were found massively produced in the nodules but not identified during this screening was examined. Mutant analysis suggested that in addition to the EtfAB system, the fixA locus is required for symbiotic efficiency.
Biswapriya Biswavas Misra's insight:
Abstract: Rhizobia are soil bacteria that are able to form symbiosis with plant hosts of the legume family. These associations result in the formation of organs, called nodules in which bacteria fix atmospheric nitrogen to the benefit of the plant. Most of our knowledge on the metabolism and the physiology of the bacteria during symbiosis derives from studying roots nodules of terrestrial plants. Here we used a proteomics approach to investigate the bacterial physiology of photosynthetic Bradyrhizobium sp. ORS278 during the symbiotic process with the semi aquatical plant Aeschynomene indica that forms root and stem nodules. We analyzed the proteomes of bacteria extracted from each type of nodule. First, we analyzed the bacteroid proteome at two different time points and found only minor variation between the bacterial proteomes of 2-week- and 3-week-old nodules. High conservation of the bacteroid proteome was also found when comparing stem nodules and root nodules. Among the stem nodule specific proteins were those related to the phototrophic ability of Bradyrhizobium sp. ORS278. Furthermore, we compared our data with those obtained during an extensive genetic screen previously published. The symbiotic role of four candidate genes which corresponding proteins were found massively produced in the nodules but not identified during this screening was examined. Mutant analysis suggested that in addition to the EtfAB system, the fixA locus is required for symbiotic efficiency.
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Plant Biotechnology

Plant Biotechnology | PlantBioInnovation | Scoop.it
Amazon.in - Buy Plant Biotechnology book online at best prices in india on Amazon.in. Read Plant Biotechnology book reviews & author details and more at Amazon.in. Free delivery on qualified orders.
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Rapid bioassay to measure early reactive oxygen species production in Arabidopsis leave tissue in response to living Pseudomonas syringae

Arabidopsis thaliana and Pseudomonas syringae pathovar tomato (Pto) provide an excellent plant-bacteria model system to study innate immunity. During pattern-triggered immunity (PTI), cognate host receptors perceive pathogen-associated molecular patterns (PAMPs) as non-self molecules. Pto harbors many PAMPs; thus for experimental ease, many studies utilize single synthesized PAMPs such as flg22, a short protein peptide derived from Pseudomonas flagellin. Flg22 recognition by Arabidopsis Flagellin Sensing 2 (FLS2) initiates a plethora of signaling responses including rapid production of apoplastic reactive oxygen species (ROS). Assessing flg22-ROS has been instrumental in identifying novel PAMP-signaling components; but comparably little is known whether in Arabidopsis, ROS is produced in response to intact live Pto and whether this response can be used to dissect genetic requirements of the plant host and live bacterial pathogens in planta.
Biswapriya Biswavas Misra's insight:
Background

Arabidopsis thaliana and Pseudomonas syringae pathovar tomato (Pto) provide an excellent plant-bacteria model system to study innate immunity. During pattern-triggered immunity (PTI), cognate host receptors perceive pathogen-associated molecular patterns (PAMPs) as non-self molecules. Pto harbors many PAMPs; thus for experimental ease, many studies utilize single synthesized PAMPs such as flg22, a short protein peptide derived from Pseudomonas flagellin. Flg22 recognition by Arabidopsis Flagellin Sensing 2 (FLS2) initiates a plethora of signaling responses including rapid production of apoplastic reactive oxygen species (ROS). Assessing flg22-ROS has been instrumental in identifying novel PAMP-signaling components; but comparably little is known whether in Arabidopsis, ROS is produced in response to intact live Pto and whether this response can be used to dissect genetic requirements of the plant host and live bacterial pathogens in planta.

Results

Here, we report of a fast and robust bioassay to quantitatively assess early ROS in Arabidopsis leaves, a tissue commonly used for pathogen infection assays, in response to living bacterial Pto strains. We establish that live Pto elicits a transient and dose-dependent ROS that differed in timing of initiation, amplitude and duration compared to flg22-induced ROS. Our control experiments confirmed that the detected ROS was dependent on the presence of the bacterial cells. Utilizing Arabidopsis mutants previously shown to be defective in flg22-induced ROS, we demonstrate that ROS elicited by live Pto was fully or in part dependent on RbohD and BAK1, respectively. Because fls2 mutants did not produce any ROS, flagellin perception by FLS2 is the predominant recognition event in live Pto-elicited ROS in Arabidopsis leaves. Furthermore using different Pto strains, our in planta results indicate that early ROS production appeared to be independent of the Type III Secretion System.

Conclusions

We provide evidence and necessary control experiments demonstrating that in planta, this ROS bioassay can be utilized to rapidly screen different Arabidopsis mutant lines and ecotypes in combination with different bacterial strains to investigate the genetic requirements of a plant host and its pathogen. For future experiments, this robust bioassay can be easily extended beyond Arabidopsis-Pto to diverse plant-pathosystems including crop species and their respective microbial pathogens.

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The Secretory System of Arabidopsis

The Secretory System of Arabidopsis | PlantBioInnovation | Scoop.it
Diane C. Bassham, Federica Brandizzi, Marisa S. Otegui, and Anton A. Sanderfoot (2008) The Secretory System of Arabidopsis. The Arabidopsis Book: Vol. , No. , pp. null. doi: http://dx.doi.org/10.1199/tab.0116
Biswapriya Biswavas Misra's insight:

Over the past few years, a vast amount of research has illuminated the workings of the secretory system of eukaryotic cells. The bulk of this work has been focused on the yeast Saccharomyces cerevisiae, or on mammalian cells. At a superficial level, plants are typical eukaryotes with respect to the operation of the secretory system; however, important differences emerge in the function and appearance of endomembrane organelles. In particular, the plant secretory system has specialized in several ways to support the synthesis of many components of the complex cell wall, and specialized kinds of vacuole have taken on a protein storage role—a role that is intended to support the growing seedling, but has been co-opted to support human life in the seeds of many crop plants. In the past, most research on the plant secretory system has been guided by results in mammalian or fungal systems but recently plants have begun to stand on their own as models for understanding complex trafficking events within the eukaryotic endomembrane system.

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TFBMs of NBS-LRR Genes of Rice and Arabidopsis

TFBMs of NBS-LRR Genes of Rice and Arabidopsis | PlantBioInnovation | Scoop.it
Biswapriya Biswavas Misra's insight:

Nucleotide binding site leucine rich repeat (NBS-LRR) gene encoding proteins are the major biotic stress resistance genes of rice and Arabidopsis thaliana. Upstream sequences of 206 entire NBS-LRR genes of Arabidopsis and 120 genes of rice were analyzed with three highly reliable motif prediction tools for enhanced accuracy of prediction and characterization of potential transcription factor binding motifs (TFBMs). A total of 36 and 30 novel, strong TFBMs were discovered from NBS-LRR genes of rice and A. thaliana, respectively. All the motifs identified in these sequences were analyzed for their positional conservation and the possible motif network associations were also identified. Further, the probability of the presence of motifs in these NBS-LRR genes were validated and statistically tested. Although Arabidopsis NBS-LRR sequences showed 76.3% similarity with rice sequences at motif level, the analysis revealed that rice sequences have many unique TFBMs and are more evolved in gene expression mechanisms. The study also provided a list of novel candidate motifs for these genes, which will be a good resource for experimental validation. A novel strategy of prediction of gene expression based on motif arrangement was also demonstrated in this study. The findings of this study, such as the motifs’ positional conservation, ­architecture, etc. offered new biological insights into the role of TFBMs in the regulation of resistance genes.

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Biotechnology and Plant BreedingAluízio Borém, Roberto Fritsche-Neto

Biotechnology and Plant BreedingAluízio Borém, Roberto Fritsche-Neto | PlantBioInnovation | Scoop.it
Elsevier Store: Biotechnology and Plant Breeding, 1st Edition from Aluízio Borém, Roberto Fritsche-Neto.
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Genomics research on non-model plant pathogens: delivering novel insights into rust fungus biology

Genomics research on non-model plant pathogens: delivering novel insights into rust fungus biology | PlantBioInnovation | Scoop.it

The goal of this research topic is to gather articles that present recent advances in the understanding of rust fungus biology, their complex lifecycles and obligate biotrophic interactions with their hosts, through the means of genomics and proteomics. This includes genome sequencing and/or resequencing of isolates, RNA-Seq or large-scale transcriptome analyses, genome-scale detailed annotation of gene families, conformation of genes and/or expression of gene complements via proteomics, and comparative analyses among the various rust fungi and, where feasible, with other obligate biotrophs or fungi displaying distinct trophic modes.


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julien levy's curator insight, March 6, 5:24 PM

Non model disease, non model pathogens and non model plants, genomics and proteomics are really useful tools.

 

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Plant-type ferredoxin-NADP+ reductases: a basal structural framework and a multiplicity of functions.

Biswapriya Biswavas Misra's insight:

Ferredoxin-NADP+ (oxido)reductase (EC 1.18.1.2, FNR) is an FAD-containing enzyme that catalyzes the reversible electron transfer between NADP(H) and electron carrier proteins such as ferredoxin and flavodoxin. Isoforms of this flavoprotein are present in chloroplasts, mitochondria, and bacteria in which they participate in a wide variety of redox metabolic pathways. Although ferredoxin-NADP+ reductases have been thoroughly investigated and their properties reviewed on several occasions, considerable advances in the understanding of these flavoenzymes have occurred in the last few years, including the characterization of cDNA and genomic clones encoding FNR proteins from plants, algae, vertebrates, and bacteria, determination of the atomic structure of a plant FNR at high resolution, and the expression of functional reductases in microorganisms like Escherichia coli and Saccharomyces cerevisiae. The aim of this article is to summarize information gained through these recent developments, including the phylogenetic relationships among ferredoxin reductases and the key structural features of the plant FNR family. Other aspects such as the catalytic mechanism of FNR and the molecular events underlying biogenesis, intracellular sorting, folding, and holoenzyme assembly of this important flavoenzyme are also discussed in some detail. Ferredoxin-NADP+ reductases display several outstanding properties that make them excellent model proteins to address broad biological questions.

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Deep functional redundancy between FAMA and FOUR LIPS in stomatal development

Deep functional redundancy between FAMA and FOUR LIPS in stomatal development | PlantBioInnovation | Scoop.it
Biswapriya Biswavas Misra's insight:

Functional redundancy arises between gene paralogs as well as non-homologous genes that play a common role at a shared node. The bHLH transcription factor FAMA, along with the paralogous MYB genes, FOUR LIPS (FLP) and MYB88 all ensure that Arabidopsis stomata contain just two guard cells (GCs) by enforcing a single symmetric precursor cell division before stomatal mature. Consistent with this function, FLP and FAMA exhibit the same expression pattern in which both translational GFP fusions emit fluorescence just before and after symmetric division. However, FAMA but not FLP is required to confer GC fate (Ohashi-Ito and Bergmann, 2006). Strikingly, swapping the genes and promoters of the FLP and FAMA genes results in the reciprocal complementation of respective loss of function mutants. Thus, a FLP transgene can restore GC fate to a fama mutant background. FAMA, FLP, and the FLP paralog MYB88 were previously shown to influence higher order functions in stomatal development including maintaining and stabilizing stomatal fate. Here we show that these overlapping functions likely also involve interactions between FLP and FAMA with the RETINOBLASTOMA-RELATED (RBR) protein.

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