Phytochrome-interacting factors (PIFs) are known to regulate plant growth
and development, but their roles in drought stress remain unknown.
Researchers led by Yong Gao from Yangzhou University in China studied the
function of a maize (Zea mays) PIF transcription factor, ZmPIF1.

The expression level of ZmPIF1 was found to be induced by drought and
abscisic acid (ABA) treatments. The team then expressed ZmPIF1 in rice and
Arabidopsis. Both transgenic rice and Arabidopsis displayed water saving and
drought resistance traits, which were associated with reduced a stomatal
aperture and transpiration rate.

The ZmPIF1 transgenic rice plants were found to be hypersensitive to ABA
treatment without any changes in endogenous ABA level. This suggests that
ZmPIF1 was a positive regulator of the ABA signaling pathway. In addition,
ZmPIF1 was able to increase the grain yield through an increase in tiller
and panicle numbers in transgenic rice.

Based on the results, ZmPIF1 is vital in the ABA-controlled regulation of
stomatal closure to control water loss and it can enhance drought resistance
and yield in rice.



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