DOES ABA SENSITIVITY ENHANCE DROUGHT RESISTANCE? - THE DILEMMA
On one hand: (2016)
Purdue University News Release (2016): “Transgenic Plants 'Die and Let Live' Strategy Dramatically Increases Drought Resistance” - released by… Yang Zhao, Zhulong Chana, Jinghui Gao, Lu Xing, Minjie Cao, Chunmei Yu, Yuanlei Hu, Jun You, Haitao Shi, Yingfang Zhu, Yuehu Gong, Zixin Mu, Haiqing Wang, Xin Deng, Pengcheng Wang, Ray A. Bressan, and Jian-Kang Zhu. 2016. ABA receptor PYL9 promotes drought resistance and leaf senescence. doi: 10.1073/pnas.1522840113.
“We identified transgenic plants that are extremely resistant to drought from a large-scale screening of transgenic plants overexpressing the pyrabactin resistance 1-like (PYL) family of abscisic acid (ABA) receptors. We explored how these plants resist drought by examining both short-term responses, such as stomatal closure, and long-term responses, such as senescence. The physiological roles of ABA-induced senescence under stress conditions and the underlying molecular mechanism are unclear. Here, we found that ABA induces senescence by activating ABA-responsive element-binding factors and Related to ABA-Insensitive 3/VP1 transcription factors through core ABA signaling. Our results suggest that PYL9 promotes drought resistance by not only limiting transpirational water loss but also, causing summer dormancy-like responses, such as senescence, in old leaves and growth inhibition in young tissues under severe drought conditions.”
On the other hand: (2014)
Hyunmi Kim, Kyeyoon Lee, Hyunsik Hwang, Nikita Bhatnagar, Dool-Yi Kim, In Sun Yoon, Myung-Ok Byun, Sun Tae Kim, Ki-Hong Jung and Beom-Gi Kim. 2014. Overexpression of PYL5 in rice enhances drought tolerance, inhibits growth, and modulates gene expression. Jour.Exp.Bot.65:453-464.
“…However, it slightly reduced plant height under paddy field conditions and severely reduced total seed yield.”