Cytokinin-mediated source ⁄sink modifications improve drought tolerance and increase grain yield in rice under water-stress

Authors

Zvi Peleg, University of California, Davis
Maria Reguera, University of California, Davis
Ellen Tumimbang, University of California, Davis
Harkamal Walia, University of Nebraska-LincolnFollow
Eduardo Blumwald, University of California, DavisFollow

Date of this Version

2011

Citation

2011 The Authors Plant Biotechnology Journal

2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd

doi: 10.1111/j.1467-7652.2010.00584.x

Comments

Plant Biotechnology Journal (2011) 9, pp. 747–758

Abstract

Drought is the major environmental factor limiting crop productivity worldwide. We hypothesized that it is possible to enhance drought tolerance by delaying stress-induced senescence through the stress-induced synthesis of cytokinins in crop-plants. We generated transgenic rice (Oryza sativa) plants expressing an isopentenyltransferase (IPT) gene driven by PSARK, a stress- and maturation-induced promoter. Plants were tested for drought tolerance at two yield-sensitive developmental stages: pre- and post-anthesis. Under both treatments, the transgenic rice plants exhibited delayed response to stress with significantly higher grain yield (GY) when compared to wild-type plants. Gene expression analysis revealed a significant shift in expression of hormone-associated genes in the transgenic plants. During water-stress (WS), PSARK::IPT plants displayed increased expression of brassinosteroid-related genes and repression of jasmonate-related genes. Changes in hormone homeostasis were associated with resource(s) mobilization during stress. The transgenic plants displayed differential expression of genes encoding enzymes associated with hormone synthesis and hormone-regulated pathways. These changes and associated hormonal crosstalk resulted in the modification of source ⁄ sink relationships and a stronger sink capacity of the PSARK::IPT plants during WS. As a result, the transgenic plants had higher GY with improved quality (nutrients and starch content).