Delayed Leaf Senescence Induces Extreme Drought Tolerance in a Flowering Plant

Source from:  pnas.org November 28, 2007 11/30/2007

Rosa M. Rivero*, Mikiko Kojima, Amira Gepstein, Hitoshi Sakakibara, Ron Mittler,¶, Shimon Gepstein, and Eduardo Blumwald*,|| *Department of Plant Sciences, University of California, Davis, CA 95616; RIKEN Plant Science Center, 1-7-22 Suehiro-cho, Tsurumi-ku, Yokohama, Kanagawa 230-0045, Japan; Department of Biology, Technion, Haifa 32000, Israel; Department of Biochemistry and Molecular Biology, University of Nevada, Reno, NV 89557-0042; and ¶Department of Plant Science, Hebrew University of Jerusalem, Jerusalem 91905, Israel Communicated by Emanuel Epstein, University of California, Davis, CA, October 11, 2007 (received for review July 30, 2007) Abstract Drought, the most prominent threat to agricultural production worldwide, accelerates leaf senescence, leading to a decrease in canopy size, loss in photosynthesis and reduced yields. On the basis of the assumption that senescence is a type of cell death program that could be inappropriately activated during drought, we hypothesized that it may be possible to enhance drought tolerance by delaying drought-induced leaf senescence. We generated transgenic plants expressing an isopentenyltransferase gene driven by a stress- and maturation-induced promoter. Remarkably, the suppression of drought-induced leaf senescence resulted in outstanding drought tolerance as shown by, among other responses, vigorous growth after a long drought period that killed the control plants. The transgenic plants maintained high water contents and retained photosynthetic activity (albeit at a reduced level) during the drought. Moreover, the transgenic plants displayed minimal yield loss when watered with only 30% of the amount of water used under control conditions. The production of drought-tolerant crops able to grow under restricted water regimes without diminution of yield would minimize drought-related losses and ensure food production in water-limited lands. Enditem