Delayed leaf senescence induces extreme drought tolerance in a flowering plant

TLDR

Drought accelerates leaf senescence, reducing canopy size, photosynthesis, and yields, and developing drought‑tolerant crops that maintain yield under limited water is essential to mitigate these losses. We hypothesized that delaying drought‑induced leaf senescence could enhance drought tolerance. Transgenic plants expressing an isopentenyltransferase gene under a stress‑ and maturation‑induced promoter were generated. Suppressing drought‑induced leaf senescence conferred exceptional drought tolerance, enabling vigorous growth after prolonged drought, maintaining high water content and photosynthetic activity, and sustaining near‑normal yields with only 30 % of the water used by controls.

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.