VARGENDROUTOLBRACHY · Natural variation for drought tolerance in the grass Brachypodium distachyon, a new model species for ecological genomics

Natural variation for drought tolerance in the grass Brachypodium distachyon, a new model species for ecological genomics

Many advances in plant sciences have arisen from research on the mustard, Arabidopsis thaliana. However, relevance of this system for cereal crops of agricultural importance has been unclear, especially for yield and plant responses to diverse abiotic and biotic stresses. Especially challenging are agricultural species with complex genomes, or with low genome similarity to plant models. There is a real need for finding new plant models closer to plants with high socioeconomic interest that provide new answers to the present-day environmental challenges around the planet. For temperate grasses, a new plant model, Brachypodium distachyon, has recently emerged to address key long-term questions in plant functional genomics and ecology, such as, what is the origin of the variation of plant tolerance to drought or pests. We consider approaches to screening natural variation, with the goal of identifying genomic regions underlying natural polymorphism in drought tolerance traits in this species using an eco-genomic perspective. This basic information may be transferred and implemented in related grasses with socioeconomic interest. Objectives Our research seeks to provide the first comprehensive ecological and evolutionary analysis of the genetic basis of the wild grass B. distachyon adaptation to dry environments. Work performed We have created a germoplasm bank that includes 1054 accessions of B. distachyon collected from 57 populations across the Iberian Peninsula. We have examined the patterns of genetic variation in plant traits directly related to drought tolerance (Water Use Efficiency or WUE, and flowering time) in 192 diploids and polyploids accessions of B. distachyon from Spain and Portugal. We have screened more than 500 genotypes to determine their ploidy level and their variation across the Iberian Peninsula populations. Using molecular markers, we have genotyped 223 individuals from 24 populations across a geographical gradient in Spain. Finally, we have conducted ecological experiments in B. distachyon natural populations to detect patterns of local adaptation to aridity. Main Results We have detected a significant amount of genetic variation for drought tolerance traits in B. distachyon. Such variation is significantly associated to the ploidy level (diploids vs. allotetraploids). Overall, tetraploid accessions have higher WUE and earlier flowering times than diploid ones. These two traits are considered to be adaptive for tolerating drought stress. We have determined that ploidy level of B. distachyon is geographically structured and significant correlated with the geographical variation in aridity. Significant natural genetic variation for WUE and flowering time among plants exists within each ploidy level. Among diploid accessions, genetic variation in WUE is significant and negatively related to variations in flowering time, elevation and latitude. We have crossed two parent genotypes for creating the QTL mapping population and the Recombinant Inbreed Lines (RILs). Results from our field experiments indicate that both ploidy level variation and local adaptation may play a significant role in the natural variation of life-history traits existing in B. distachyon. Expected final results and impact Future QTL analysis will determine which genetic regions control the natural variation in WUE traits and will allow performing both an evolutionary and functional analyses on these genes. From the evolutionary side, we will be able to understand the origin of the natural polymorpism in drought tolerance traits in B. distachyon at molecular level. In particular, we will respond whether local adaptation and/or polyploidization are the evolutionary forces that originate and promote such variation. From a socioecomic view, future cloning of these genes will allow study both their function and their potential transformation and transference to economically important cereals. Project webpage www.ajmanzaneda.org

Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз