Study : Tuning water use efficiency and drought tolerance in wheat using ABA receptors


Tuning water use efficiency and drought tolerance in wheat using ABA receptors
Water availability is a key determinant of terrestrial plant productivity. Many climate models predict that water stress will increasingly challenge agricultural yields and exacerbate projected food deficits. To ensure food security and increase agricultural efficiency, crop water productivity must be increased. Research over past decades has established that the phytohormone abscisic acid (ABA) is a central regulator of water use and directly regulates stomatal opening and transpiration. In this study, we investigated whether the water productivity of wheat could be improved by increasing its ABA sensitivity. We show that overexpression of a wheat ABA receptor increases wheat ABA sensitivity, which significantly lowers a plant’s lifetime water consumption. Physiological analyses demonstrated that this water-saving trait is a consequence of reduced transpiration and a concomitant increase in photosynthetic activity, which together boost grain production per liter of water and protect productivity during water deficit. Our findings provide a general strategy for increasing water productivity that should be applicable to other crops because of the high conservation of the ABA signaling pathway. Overall design: One representative transgenic line (TaPYLox) and its background non-transgenic cultivar (Null; cv. Fielder) were subjected to the analysis. The transcriptome was analyzed using three biological replicates of RNA samples from leaves of 40-day-old plants after exposure to one of three stress conditions. The three treatments were as follows: WWC, corresponding to normal conditions (soil water potential [SWP] > -110 kPa); ABA, namely, incubation for 24 h after spraying with 25 μM ABA; and drought, involving incubation for 24 h after withholding water to maintain SWP < -390 kPa. Each total RNA was isolated using the RNeasy® Plant Mini Kit (Qiagen) and evaluated for quality and quantity with an Agilent 2100 Bioanalyzer (Agilent Technologies) and the Agilent RNA 6000 Nano Kit (Agilent Technologies). Library preparation was performed according to the TruSeq RNA Sample Preparation v2 guide (Illumina). Sequencing on an Illumina HiSeq® 2500 system generated an average of 91.3 M paired-end reads (2 × 101 nt) per library.


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