Identificación y caracterización de genes implicados en la variación natural para el patrón de tricomas en Arabidopsis

Abstract

Arabidopsis thaliana is the main research model plant, which is widely used to determine the genetic and molecular mechanisms involved in the development and physiology of annual plants. In addition, thanks to its broad geographic distribution and its large amount of natural genetic diversity, A. thaliana has also become recently a model plant to study ecological and evolutionary processes. In particular, our laboratory is interested in understanding the genetic, molecular and evolutionary bases of the natural variation for trichome patterning because this trait has been involved in adaptation to numerous abiotic and biotic stress factors. To this end, we are exploiting a regional collection of 174 A. thaliana accessions from the Iberian Peninsula, which has been previously characterized at the genomic and environmental level. Interestingly, several accessions have been identified in this collection as developing trichomes in fruits, and previous genetic analyses have shown that this trait is determined by five loci named as Fruit Trichome Density (FTD1-5). This thesis aims to identify new genetic and molecular components contributing to the natural variation for trichome patterning in A. thaliana, both in vegetative and reproductive phases, and in response to herbivory. To achieve this goal, the following tasks have been carried out: 1. Genome-wide association analyses for trichome patterning in different organs of the vegetative and reproductive phases have been done by analysing phenotypically 174 accessions of the regional collection from the Iberian Peninsula. This study has identified several known (eg. ETC1, MYC1) and new (eg. At2g04925, At2g40130, At4g04985 y At5g53420) candidate genes that likely contribute to the natural variation for trichome patterning in one or several plant organs, or in response to jasmonic acid treatment, as a proxy of herbivory. 2. A high-resolution fine mapping has been done for FTD1 locus using a large experimental population derived from the cross between accessions Ler and Doñ-0. This analysis has identified EGL3 as the only candidate gene for FTD1, for which Doñ-0 accession carries a gain-of-function allele. 3. The genes underlying FTD2, FTD3 and FTD5 loci have been identified by means of phenotypic and molecular characterization of numerous transgenic lines carrying different natural alleles of candidate genes. Thus, it has been demonstrated that TCL1, GL1 and TRY are the genes causing the development of trichomes in fruits of A. thaliana.