Chickpea (Cicer arietinum L.) is the second most widely grown pulse and drought (limiting water) is one of the major constraints leading to about 40–50% yield losses annually. Dehydration responsive element binding proteins (DREBs) are important plant transcription factors that regulate the expression of many stress-inducible genes and play a critical role in improving the abiotic stress tolerance. Transgenic chickpea lines harbouring transcription factor, Dehydration Responsive Element-Binding protein 1A from Arabidopsis thaliana (AtDREB1a gene) driven by stress inducible promoter rd29a were developed, with the intent of enhancing drought tolerance in chickpea. Performance of the progenies of one transgenic event and control were assessed based on key physiological traits imparting drought tolerance such as plant water relation characteristics, chlorophyll retention, photosynthesis, membrane stability and water use efficiency under water stressed conditions. Four transgenic chickpea lines harbouring stress inducible AtDREB1a were generated with transformation efficiency of 0.1%. The integration, transmission and regulated expression were confirmed by Polymerase Chain Reaction (PCR), Southern Blot hybridization and Reverse Transcriptase polymerase chain reaction (RT-PCR), respectively. Transgenic chickpea lines exhibited higher relative water content, longer chlorophyll retention capacity and higher osmotic adjustment under severe drought stress (stress level 4), as compared to control. The enhanced drought tolerance in transgenic chickpea lines were also manifested by undeterred photosynthesis involving enhanced quantum yield of PSII, electron transport rate at saturated irradiance levels and maintaining higher relative water content in leaves under relatively severe soil water deficit. Further, lower values of carbon isotope discrimination in some transgenic chickpea lines indicated higher water use efficiency. Transgenic chickpea lines exhibiting better OA resulted in higher seed yield, with progressive increase in water stress, as compared to control. Based on precise phenotyping, involving non-invasive chlorophyll fluorescence imaging, carbon isotope discrimination, osmotic adjustment, higher chlorophyll retention and membrane stability index, it can be concluded that AtDREB1a transgenic chickpea lines were better adapted to water deficit by modifying important physiological traits. The selected transgenic chickpea event would be a valuable resource that can be used in pre-breeding or directly in varietal development programs for enhanced drought tolerance under parched conditions.

中文翻译：

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含有 AtDREB1a 的转基因鹰嘴豆 (Cicer arietinum L.) 在生理上更能适应缺水


鹰嘴豆 (Cicer arietinum L.) 是种植第二广泛的豆类，干旱（限制水分）是导致每年约 40-50% 产量损失的主要限制因素之一。脱水反应元件结合蛋白（DREB）是重要的植物转录因子，调节许多胁迫诱导基因的表达，在提高非生物胁迫耐受性中发挥着关键作用。转基因鹰嘴豆品系含有由胁迫诱导启动子 rd29a 驱动的拟南芥脱水响应元件结合蛋白 1A（AtDREB1a 基因），旨在增强鹰嘴豆的耐旱性。基于赋予耐旱性的关键生理性状，例如植物水分关系特征、叶绿素保留、光合作用、膜稳定性和水分胁迫条件下的水分利用效率，评估一种转基因事件和对照的后代的表现。产生了四个带有胁迫诱导型 AtDREB1a 的转基因鹰嘴豆品系，转化效率为 0.1%。分别通过聚合酶链式反应(PCR)、Southern Blot杂交和逆转录酶聚合酶链式反应(RT-PCR)证实了整合、传递和调节表达。与对照相比，转基因鹰嘴豆品系在严重干旱胁迫（胁迫水平4）下表现出更高的相对含水量、更长的叶绿素保留能力和更高的渗透调节。 转基因鹰嘴豆品系的耐旱性增强还表现在不受阻碍的光合作用，包括提高 PSII 的量子产量、饱和辐照水平下的电子传输速率以及在相对严重的土壤水分亏缺下保持叶片中较高的相对含水量。此外，一些转基因鹰嘴豆品系中较低的碳同位素辨别值表明较高的水利用效率。与对照相比，表现出更好的OA的转基因鹰嘴豆品系导致更高的种子产量，并且水分胁迫逐渐增加。基于精确的表型分析，包括非侵入性叶绿素荧光成像、碳同位素辨别、渗透调节、更高的叶绿素保留和膜稳定性指数，可以得出结论，AtDREB1a转基因鹰嘴豆品系通过改变重要的生理性状更好地适应缺水。选定的转基因鹰嘴豆事件将是一种宝贵的资源，可用于预育种或直接用于品种开发计划，以增强干旱条件下的耐旱性。