Drought Tolerant Plants by Delaying Leaf Senescence

Plants use different strategies to avoid or tolerate drought stress such as closing of stomata or shedding of leaves. These measures allow them to conserve water. A group of international scientists from the US, Japan and Israel successfully obtained drought-tolerant tobacco plants by modifying the mechanism that induces leaf senescence during drought.

The scientists modified the expression of the IFT gene, responsible for controlling the levels of the hormone cytokinin. Cytokinin is responsible for promoting cell division as well as controlling a variety of plant physiological processes, cell growth and differentiation. IFT expression was modified by using stress- and maturation-induced promoters (DNA sequences that control the translation of genes next to it). At the onset of stress signaling, tissues facing drought-induced stress produce high levels of cytokinin, thus preventing leaf senescence. The transgenic plants displayed minimal yield loss when watered with only 30 percent of the amount of water used in control conditions. The GM plants also exhibited vigorous growth after a long drought period that killed the control plants.

The abstract of the paper published by PNAS is available at http://www.pnas.org/cgi/content/abstract/104/49/19631 The full paper is available to subscribers at http://www.pnas.org/cgi/reprint/104/49/19631