The goal of this work was to identify genetic variants underlying a well-characterized environmental response, the elongation of Arabidopsis thaliana hypocotyls (seedling stems) in response to shade, otherwise known as shade avoidance. We performed a genome-wide association study with four phenotypes: absolute hypocotyl height of plants grown in both simulated sun and shade and two measures of how height responded to shade. With this study, we confirmed previous findings that variants in two photoreceptors were associated with hypocotyl height variation. We also found associations with genetic variants in previously-identified shade avoidance genes, as well as with variants in genes not typically considered part of the shade avoidance pathway. By examining patterns of which of the four phenotypes were associated with each gene, we were then able to discriminate between genetic variants that have a general role in hypocotyl height variation and variants that are specifically involved in the shade avoidance response. We also found that shade avoidance was not broadly associated with geography, suggesting that variation in this trait may be due to local differences in light quality.
The 23rd International Conference on Arabidopsis Research (ICAR) will be held at the Hofburg Imperial Palace in Vienna, Austria from 3-7 July 2012. The annual conference is the largest gathering of scientists working on the model plant Arabidopsis. Over 800 participants from around the world are expected to attend the four day meeting.
We would like to invite all interested researchers to join us in one of Europe's most beautiful cities for this exciting event. With over 70 invited international speakers and more than 500 posters, ICAR 2012 will showcase the latest cutting-edge research.
The phytohormone auxin plays critical roles in the regulation of plant growth and development. Indole-3-acetic acid (IAA) has been recognized as the major auxin for more than 70 y. Although several pathways have been proposed, how auxin is synthesized in plants is still unclear. Previous genetic and enzymatic studies demonstrated that both TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAA) and YUCCA (YUC) flavin monooxygenase-like proteins are required for biosynthesis of IAA during plant development, but these enzymes were placed in two independent pathways. In this article, we demonstrate that the TAA family produces indole-3-pyruvic acid (IPA) and the YUC family functions in the conversion of IPA to IAA in Arabidopsis (Arabidopsis thaliana) by a quantification method of IPA using liquid chromatography–electrospray ionization–tandem MS. We further show that YUC protein expressed in Escherichia coli directly converts IPA to IAA. Indole-3-acetaldehyde is probably not a precursor of IAA in the IPA pathway. Our results indicate that YUC proteins catalyze a rate-limiting step of the IPA pathway, which is the main IAA biosynthesis pathway in Arabidopsis.
Plants regularly face adverse growth conditions, such as drought, salinity, chilling, freezing, and high temperatures. These stresses can delay growth and development, reduce productivity, and, in extreme cases, cause plant death. Plant stress responses are dynamic and involve complex cross-talk between different regulatory levels, including adjustment of metabolism and gene expression for physiological and morphological adaptation. In this review, information about metabolic regulation in response to drought, extreme temperature, and salinity stress is summarized and the signalling events involved in mediating stress-induced metabolic changes are presented.
One of the main strengths of Arabidopsis thaliana as a model species is the impressive number of public resources available to the scientific community. Exploring species genetic diversity — and therefore adaptation — relies on collections of individuals from natural populations collected from diverse environments. Nevertheless, due to a few mislabeling events or genotype mixtures, some variants available in stock centers have been misidentified, causing inconsistencies and limiting the potential of genetic analyses. To improve identification of natural accessions, we genotyped 1,311 seed stocks from our Versailles Arabidopsis Stock Center and from other collections to determine their molecular profiles at 341 SNP markers. These profiles were used to compare genotypes at both the intra- and inter-accession levels. We confirmed previously-described inconsistencies and revealed new ones and suggest likely identities for accessions whose lineage had been lost. We also developed two new tools: a minimal fingerprint computation to quickly verify the identity of an accession, and an optimized marker set to assist in the identification of unknown or mixed accessions. These tools are available on a dedicated web interface called ANATool (https://www.versailles.inra.fr/ijpb/crb/anatool) that provides a simple and efficient means to verify or determine the identity of A. thaliana accessions in any laboratory, without the need for any specific or expensive technology.