Small peptide regulation of plant drought tolerance

Drought is a major natural disaster for agriculture. Developing drought-tolerant crop plants is an important way to mitigate the impact of drought on crop production yet this requires a better understanding of the genetic basis of plant drought tolerance. Transpiration is the major route of water loss and is inherently linked to drought tolerance of the plant. Transpiration cools down leaves and leaf temperature could thus be used to assess drought tolerance of the plant. In a forward genetic screen using infrared imaging, we isolated several mutants with mutations in small peptide and receptor-like kinase genes that exhibit altered leaf temperatures. The current study will investigate one such a peptide, IDL3, which belongs to a small gene family whose members are required for floral organ abscission yet their functions in drought responses are unclear. The idl3 mutant plants have lower leaf temperatures and higher transpiration rates and are more susceptible to drought stress than the wild type plants. The current study will investigate how IDL3 regulates transpiration and drought tolerance of plants. The specific objectives are: 1) to determine the functions of IDL3 and its homologs in transpiration regulation, 2) to define the signaling pathway of IDL3 in regulating transpiration and drought tolerance and, 3) to investigate how IDL3 and its related pathways are regulated by developmental and environmental cues. The current study will uncover the fundamental mechanisms underlying how this conserved ligandreceptor signaling system coordinates growth and senescence with plant water use. The study may also uncover novel methods to engineer drought tolerance of crop plants.