How Do Plants Deal with Flood and Drought? Biotechnological Strategies to Enhance the Natural Response and Improve Yield

RIBICHICH, K. F.; CHAN, R. L.

ISB News Report. Agricultural and Environmental Biotechnology

Virginia Polytechnic Institute and State University

Lugar: Virginia; Año: 2015 vol. 9 p. 1 - 5

Water deficit and water excess are major factors affecting plants yield worldwide. Plants deal with water deficit by modifying some of their morphological and physiological characteristics. To cope with water excess, plants trigger one of two strategies; quiescence and escape. Quiescence involves a reduction in carbohydrate consumption for a few days, to recommence after the water drains. The escape strategy consists of the fast elongation of internodes, maintaining a low metabolic activity for months to continue growth. Water deficit and excess seem to be opposites; however, the stresses caused by these factors, as well as the responses triggered by the plants, share several common features. Transcription factors (TFs) are regulatory proteins that can induce or repress entire transduction signal pathways, including the involved in responses to abiotic stress. Common sunflower is a good candidate to select TFs potentially useful to improve tolerance to this stress because is able to grow on soils with variable water levels. In consequence, two divergent TFs, specific of sunflower and its plant family, were studied for our group: HaWRKY76 from WRKY and HaHB11 from HD-Zip I families. Expression analyses of transcripts of these TFs showed an induction caused by both water deficit and water excess treatments. Transgenic Arabidopsis plants ectopically expressing these genes driven by the constitutive 35S CaMV promoter exhibited enhanced tolerance to flooding and drought to different degrees, depending on the transgene expression level. Both types of transgenic plants displayed the quiescent strategy when flooded, whereas the mechanisms by which drought tolerance was achieved is less clear although appeared ABA-independent. Moreover, these plants exhibited enhanced yields under standard growth conditions, and fewer penalties after stress treatments, than the controls, leading us to propose the transcripts as potential biotechnological tools to improve crops.