DIFFERENTIAL RESPONSE TO OSMOTIC STRESS IN RICE: SELECTION OF TWO ITALIAN CULTIVARS FOR RNA-SEQ ANALYSIS

Abiotic stresses are the primary cause of crop loss worldwide, reducing average yields for most major crop plants by more than 50 %. Rice is particularly susceptible to dehydration, and cultivars may considerably differ in their vegetative response to water deficit. The identification of key genes regulated by water shortage is a major objective for the development of drought-tolerant varieties by molecular breeding. Here, we provide a physiological analysis of 13 Italian rice cultivars (Oryza sativa L. ssp japonica) in response to osmotic stress: Arborio, Augusto, Baldo, Balilla, Carnaroli, Eurosis, Koral, Loto, SISR215, Thaibonnet, Venere, Vialone Nano, Volano. Rice plants were grown in hydroponic culture and then subjected to PEG treatment (20% PEG 6000). The measurement of physiological parameters (leaf Relative Water Content and Electrolyte Leakage) showed that the cultivars exhibited differential responses to osmotic stress. On the basis of these data, the cultivars Eurosis and Augusto were classified as high tolerant and Loto and Vialone Nano as high sensitive. Total RNAs separately extracted from leaves and roots of Eurosis and Loto plants were used for RNA sequencing. RNA-seq data are currently under analysis. The expression profile of genes of interest, found to be differentially expressed between these two cultivars, will be further investigated in Augusto and Vialone Nano varieties. These gene expression data will be used to identify genes involved in the response to water shortage, with the aim to identify associated polymorphisms correlated with the stress response phenotype (tolerance/susceptibility). This work was supported by Progetto AGER, grant n° 2010-2369.