Análisis de la variación genética, respuesta funcional y expresión génica frente a diferentes tipos de estrés en el complejo de ploidía brachypodium distachyon (poaceae)

Resum

This PhD Thesis is focused on the study of the functional response mediated by ploidy and ancestral hybridization (i.e., alopoliploidy), as well as the genetic basis underlying the natural variation of water stress tolerance, among individuals belonging to different natural populations of the three species from the Brachypodium distachyon complex. The results in the first chapter show that the functional drought response is well differentiated at species level, being in the B. hybridum allotetraploid essentially correlated with B.stacei considering physiological traits. However, the second chapter shows that, at transcriptomic level, B.hybridum exhibits a similar expression pattern in drought response to the ancestor B.distachyon and that response is stronger compared to its two diploid ancestors. A strong induction of LEA proteins such as dehydrins is highlighted. In the third chapter, a Brachypodium distachyon transgenic line that overexpresses the dehydrin3 gene (BdDHN3) is generated and analyzed. Last chapter analyzes the variation in the response to herbivory in the complex, finding that herbivory has a significant impact on fitness in the species of the Brachypodium distachyon complex and that the condition of polyploidy does not improve the resistance and tolerance to herbivory in this complex.