Improving drought tolerance: Can comparative transcriptomics support strategic rice breeding?

Drought is one of the most critical factors that affect crop growth and development, causing plant damage and potential yield loss. Water shortage is a global concern, and the impact of climate change will further reduce water supply for agriculture. Therefore, there is a huge need to increase agricultural production through improved adaptation of cropping systems and design of new plant varieties. Rice (Oryza sativa L.), a primary source of food worldwide, is highly sensitive to water deficit and the development of drought-tolerant rice varieties represents a key strategy for breeding programs. Transcriptomics can significantly support the identification of genes and regulatory networks regulating plant responses to environmental fluctuations. Comparative transcriptomic studies, that analysed rice genotypes with contrasting responses to water stress, allow the exploitation of the natural genetic variation present in rice genotypes and represent a powerful tool for discovering genes involved in drought tolerance. Differentially expressed genes between tolerant and sensitive genotypes represent ideal candidates for further characterization and allele mining in the attempt to identify useful alleles to accelerate breeding programs. The acquired knowledge from comparative transcriptomic studies can support breeding for the identification of good agronomic traits in rice genome, to improve drought tolerance and crop yield.