Genes Involved in Drought Stress Response and Tolerance in Wild Peanut Relatives

Drought is one of the main constraints to peanut production in the tropics. Wild relatives have a broader genetic base and have adapted to a range of environments throughout evolution, constituting a rich source of resistance/tolerance alleles to biotic and abiotic stresses. Arachis duranensis and A. magna (AA and BB genomes, respectively) showed the most conservative transpiration profile under water limited conditions when compared to other wild diploids and cultivated tetraploids. In silico analysis of A. duranensis (454 sequencing) and A. magna(SSH) transcriptome during progressive water deficit revealed several differentially expressed genes involved in drought responses. From that, the expression profile of selected candidate genes was validated by qRT-PCR, revealing a number of drought responsive genes such as those involved in signal transduction as NAC and bZIP, others which better enable plants to  survive under stress conditions, as those involved in the adaptation of primary metabolism, such as CA or NIT, or coding for proteins implicated in the cell protection or adaptation mechanisms, like CDSP, DiP or EXLB. This transcriptome data is a valuable resource for gene discovery which can be used to enhance drought tolerance by gene manipulation in bio-engineered crops including peanut and other legumes. This study can also contribute to a better understanding of gene modulation in response to drought stress in legumes, and to peanut breeding programs, as it allows the characterization of new alleles and the development of molecular markers associated to drought stress.

Financial support: Embrapa, CNPq and Generation Challenge Program