Water deficit stress tolerance in maize conferred by expression of an isopentenyltransferase (IPT) gene driven by a stress- and maturation-induced promoter

DÉCIMA ONETO, CECILIA; OTEGUI, MARÍA ELENA; BEZNEC, AILÍN; BAROLI, IRENE; FACCIO, PAULA; BOSSIO, EZEQUIEL; BLUMWALD, EDUARDO; LEWI, DALIA

Foz de Iguazú

Congreso; International Congress of Plant Molecular Biology; 2015

Senescence can be delayed in transgenic plants overexpressing the enzyme isopentiltransferase (IPT) due to stress-induced increased levels of endogenous cytokinins. This trend leads to sustained photosynthetic activity and improved tolerance to abiotic stress. The aim of this study was to generate and characterize transgenic plants of maize (Zea mays L.) transformed with the IPT gene sequence under the regulation of SARK promoter (protein kinase receptor-associated senescence). Three independent transgenic events and their segregating null controls were evaluated in two watering regimes (WW: well watered; WD: water deficit) imposed for two weeks around anthesis. Phenotyping included determination of IPT gene expression levels, concentration of growth regulators, total green leaf area (TGLA), anthesis and silking dates and their interval (ASI), plant and ear growth rates (PGR and EGR), photosynthesis and stomatal conductance, chlorophyll content, source/sink relationship, number of grains per plant (GNP), individual grain weight (GW) and plant grain yield (PGY). Our results show that the WD treatment induced IPT expression with the concomitant increase in cytokinin levels that prolonged the persistence of TGLA, and maintained normal photosynthetic rate and stomatal conductance. These trends were accompanied by a minor decrease in GNP, GW and PGY as compared to WW plants. Plants expressing the IPT gene under WD had PGR, ASI and biomass levels similar to WW plants. Our results demonstrate that expression of the IPT gene under the regulation of the SARK promoter helps improve productivity under WD conditions in C4 plants like maize.