Abstract

Functional Genomic Approaches for Plant Adaptation under Stress Conditions

Anil Singh, Senior Scientist, Indian Institute of Agricultural Biotechnology

Biotic and Abiotic stresses cause severe reduction in plant growth and productivity. These stress factors are predicted to become more severe with climate change. Plants have developed intricate mechanisms to respond and adapt to these stresses. Therefore, understanding mechanism of plant adaptation to stress conditions is prerequisite for developing plants with improved stress tolerance. We are exploiting functional genomics approaches to identify and characterize genes involved in plant stress tolerance. With the advent of high-throughput sequencing technologies, lots of genomic and transcriptomic data are being generated and deposited in public databases, which provide opportunities to identify whole gene/protein families, and shortlist a manageable number of genes for functional validation. We have identified NAC transcription factor (TF) family in potato and NBS-LRR disease resistance gene family in apple. These analyses have identified two genes of NAC TFs and 17 NBS-LRR genes, which may be important candidate genes for engineering stress/disease tolerance in plants. Abiotic stresses cause accumulation of reactive oxygen species (ROS), such as hydrogen peroxide (H2O2) in plants. CuZn-superoxide dismutase (CuZn-SOD) and ascorbate peroxidase (APX) constitute first line of defence against oxidative stress. We have developed transgenic Arabidopsis overexpressing PaSOD and RaAPX genes individually and in combination from Potentilla atrosanguinea and Rheum australe, respectively. Interestingly, PaSOD and dual transgenic lines exhibit enhanced lignin deposition in their vascular bundles with under salt stress. RNA-seq analysis revealed that expression of PaSOD gene along with RaAPX in single and dual transgenics positively regulated expression of lignin biosynthesis genes and transcription factors (NACs, MYBs, C3Hs and WRKY), leading to enhanced and ectopic deposition of lignin in vascular tissues.