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.

水分可获得性是陆生植物生产力的关键决定因素。诸多气候模型均预测，水分胁迫将日益制约农作物产量，并加剧预期的粮食缺口。为保障粮食安全、提升农业生产效率，必须提高作物水分利用效率。过往数十年的研究已证实，植物激素脱落酸（abscisic acid, ABA）是水分利用的核心调控因子，可直接调控气孔开闭与蒸腾作用。本研究旨在探究通过提升小麦对ABA的敏感性，是否可改善其水分利用效率。研究发现，过表达小麦ABA受体可提升小麦对ABA的敏感性，进而显著降低植株全生命周期的水分消耗量。生理分析表明，这一节水性状源于蒸腾作用减弱与光合活性同步提升，二者协同提高了每升水的谷物产量，并在水分胁迫期间维持植株生产力。鉴于ABA信号通路高度保守，本研究结果为提升作物水分利用效率提供了普适性策略，有望推广应用至其他农作物。实验整体设计：选取1株代表性转基因株系（TaPYLox）及其背景非转基因对照品种（Null；栽培品种Fielder）进行后续分析。针对40日龄植株叶片的RNA样本设置3次生物学重复，分别在三种胁迫处理后开展转录组分析。三种处理设置如下：WWC，代表正常生长条件（土壤水势[SWP] > -110 kPa）；ABA处理，即喷施25 μM脱落酸后培育24小时；干旱处理，即停止供水以维持土壤水势< -390 kPa，随后培育24小时。总RNA提取采用RNeasy®植物微量试剂盒（Qiagen），并使用Agilent 2100生物分析仪（Agilent Technologies）与Agilent RNA 6000 Nano试剂盒（Agilent Technologies）对RNA的质量与浓度进行质检。文库构建严格遵循TruSeq RNA样本制备v2指南（Illumina）进行。在Illumina HiSeq® 2500测序平台上进行测序，每个文库平均产出91.3百万条双端读段（2×101 nt）。