Yay! This OA review joins the list of excellent MPP "Top 10s" including viruses, bacteria and fungi. Let's hear it for the multicellular animal parasites! Can you guess which species is number one? (Hint - it's the one affecting the plant in this photo).
Symbiotic root nodules in leguminous plants result from interaction between the plant and nitrogen-fixing rhizobia bacteria. There are two major types of legume nodules, determinate and indeterminate. Determinate nodules do not have a persistent meristem while indeterminate nodules have a persistent meristem. Auxin is thought to play a role in the development of both these types of nodules. However, inhibition of rootward auxin transport at the site of nodule initiation is crucial for the development of indeterminate nodules, but not determinate nodules. Using the synthetic auxin-responsive DR5 promoter in soybean, we show that there is relatively low auxin activity during determinate nodule initiation and that it is restricted to the nodule periphery subsequently during development. To examine if and what role auxin plays in determinate nodule development, we generated soybean composite plants with altered sensitivity to auxin. We over-expressed microRNA393 to silence the auxin receptor gene family and these roots were hyposensitive to auxin. These roots nodulated normally suggesting that only minimal/reduced auxin signaling is required for determinate nodule development. We over-expressed microRNA160 to silence a set of repressor ARF transcription factors and these roots were hypersensitive to auxin. These roots were not impaired in epidermal responses to rhizobia, but had significantly reduced nodule primordium formation suggesting that auxin hypersensitivity inhibits nodule development. These roots were also hyposensitive to cytokinin, and had attenuated expression of key nodulation-associated transcription factors known to be regulated by cytokinin. We propose a regulatory feedback loop involving auxin and cytokinin during nodulation.
Turner M, Nizampatnam NR, Baron M, Coppin S, Damodaran S, Adhikari S, Arunachalam S, Yu O, Subramanian S. (2013). Plant Physiol. Jun 24. [Epub ahead of print]
Synthetic biologist Jay Keasling has already taught yeast to make the leading anti-malarial drug. His next project takes the technology a step further, using yeast to turn plant waste into diesel — and maybe gasoline and jet fuel, too.
Mary Williams's insight:
It's a nice article, and I'm a fan of Jay Keasling's work, but I object to the headline - it's not "Making fuel from yeast", it's "Yeast making fuel from plants"!
FDA’s Division of Biotechnology and GRAS Notice Review is looking for an ORISE fellow with qualifications in plant biology, molecular biology, and other appropriate fields to provide research support (data collection and analysis; non-laboratory) to our Biotechnology Consultation Program.
FDA’s Division of Biotechnology and GRAS Notice Review (DBGNR) is responsible for the evaluation of safety and nutritional assessments, which are submitted to FDA by developers of new plant varieties intended for food and feed uses. To this end, DBGNR must keep abreast of advances in the science of genetic engineering as well as of industry and academic trends in the new plant variety development, including methodology and traits. This project involves training in the evaluation of biotechnology safety and nutritional assessments under FDA’s Biotechnology Consultation Program. The participant will be expected to use this knowledge to identify and analyze the impacts of recent scientific advances and plant breeding trends to the Agency’s biotechnology policy and to provide science-based support for program improvement or further research directions.
For more specific information please contact Carrie.McMahon@fda.hhs.gov.
We are actively seeking candidates and hope to fill the position before the end of July.
This tree is Wollemia nobilis, the Wollemi pine. Its history is a great story - you can read about it here (http://en.wikipedia.org/wiki/Wollemi_pine and http://www.wollemipine.com/fast_facts.php). It's been called "One of the greatest botanical discoveries of our time", and it's a very rare tree once thought to be extinct. After a few individuals were found (in a still secret location), they were propagated, and the progeny sold for large amounts of money, which was used for further botanical research.
A call to genotype and phenotype plants stored in seed banks to bring their genetic diversity into our food system. The authors say it would cost $200 million a year - about the cost of one fighter jet!
"Plant environmental responses involve dynamic changes in growth and signaling, yet little is understood as to how progress through these events is regulated. Here, we explored the phenotypic and transcriptional events involved in the acclimation of the Arabidopsis thaliana seedling root to a rapid change in salinity. Using live-imaging analysis, we show that growth is dynamically regulated with a period of quiescence followed by recovery then homeostasis. Through the use of a new high-resolution spatio-temporal transcriptional map, we identify the key hormone signaling pathways that regulate specific transcriptional programs, predict their spatial domain of action, and link the activity of these pathways to the regulation of specific phases of growth."
Mary Williams's insight:
Wow! An amazing description of a root responding to a stressful shift in its environment. All those cells perceiving physicochemical and molecular signals, communicating amongst themselves and signaling to each other - biology at its most beautiful!
"It should be remembered that there is rarely a right or wrong answer on these sorts of issues, although some people of faith who deal more in moral absolutes might disagree with me. There are always people who have 100% conviction in their views but, as a general rule, when society is looking for the best outcome it should take such absolutist views with a pinch of salt. If you start out with certainties you are unlikely to have considered all the evidence or maybe any of the evidence."
The work, recently published in Nature Biotechnology (http://www.nature.com/nbt/journal/v30/n9/full/nbt.2346.html) explores the use of phosphite, a reduced version of phospate, as a dual purpose fertilizer and weed killer. His work suggests that by using phosphite, the limited global reserves could serve our needs for twice as long as if we continue to use it as phosphate.
One of the interesting things I learned from his talk is about the source of the enzyme phosphite oxidoreductase. It was found in Bacillus coahuilensis, which lives in a very nutrient-poor environment, Cuatro Ciénegas (http://en.wikipedia.org/wiki/Cuatro_Ci%C3%A9negas). This unique environment is one of only a few places you can find living stromatolites (colonies of cyanobacteia) - Shark Bay, Western Australia is the other well-known place to see them.