Symposium 6: Biotechnology in Creating Safe and Wholesome Foods-Molecular Approaches to Engineer Stress Tolerance in Plants

摘要

Availability of water is the most limiting factor for crop productivity and yield. Therefore, there is a strong need to understand plant adaptation mechanisms against adverse environmental conditions to improve stress tolerance. Plant stress responses involve the expression of a plethora of genes with an adaptive role. Their encoded products comprise enzymes catalyzing the synthesis of osmoprotectants or antioxidants, lipid desaturases, water channels, and ion transporters among others. Here we show the characterization of 2 different genes. First, the CpMYB10 transcription factor gene from the resurrection plant Cmterostigma plantagineum is rapidly induced by dehydration and ABA treatments in leaves and roots. Transgenic Arabidopsis thaliana plants, transformed with CpMYBlO promoter fused to GUS gene, showed reporter expression under ABA and stress conditions in several organs. Overexpression of CpMYBlO cDNA in Arabidopsis led to desiccation and salt tolerance of transgenic lines, which also exhibited glucose-insensitive and ABA-hypersensitive phenotypes. Also, the trehalose-6-phosphate synthase (AtTPS1) gene overexpressed in Arabidopsis conferred dehydration tolerance, and glucose- and ABA-insensitive phenotypes. Transgenic seedlings germinated on high concentrations of glucose developed normally, in contrast to wild type seedlings. Germination in the presence of ABA revealed higher germination rate for transgenic plants overexpressing AtTPS1. Gene-expression analysis in transgenic plants overexpressing AtTPS1 showed up-or down-regulation of several genes involved in glucose sensing and ABA signaling. Therefore, our results provide evidence that CpMYBlO and AtTPSl, when overexpressed in Arabidopsis, led to a stress-tolerance phenotype through a cross-talk to ABA and glucose signaling pathways.