Ankit Ankit, Singh Ajeet, Kumar Shailesh, Singh Amarjeet
National Institute of Plant Genome Research, New Delhi, India.
Front Plant Sci. 2023 Jan 11;13:1054821. doi: 10.3389/fpls.2022.1054821. eCollection 2022.
Potassium (K) is an essential macronutrient for plant growth and development. K deficiency hampers important plant processes, such as enzyme activation, protein synthesis, photosynthesis and stomata movement. Molecular mechanism of K deficiency tolerance has been partly understood in model plants Arabidopsis, but its knowledge in legume crop chickpea is missing. Here, morphophysiological analysis revealed that among five high yielding desi chickpea cultivars, PUSA362 shows stunted plant growth, reduced primary root growth and low K content under K deficiency. In contrast, PUSA372 had negligible effect on these parameters suggesting that PUSA362 is K deficiency sensitive and PUSA372 is a K deficiency tolerant chickpea cultivar. RNA-seq based transcriptome analysis under K deficiency revealed a total of 820 differential expressed genes (DEG's) in PUSA362 and 682 DEGs in PUSA372. These DEGs belongs to different functional categories, such as plant metabolism, signal transduction components, transcription factors, ion/nutrient transporters, phytohormone biosynthesis and signalling, and root growth and development. RNA-seq expression of randomly selected 16 DEGs was validated by RT-qPCR. Out of 16 genes, 13 showed expression pattern similar to RNA-seq expression, that verified the RNA-seq expression data. Total 258 and 159 genes were exclusively up-regulated, and 386 and 347 genes were down-regulated, respectively in PUSA362 and PUSA372. 14 DEGs showed contrasting expression pattern as they were up-regulated in PUSA362 and down-regulated in PUSA372. These include somatic embryogenesis receptor-like kinase 1, thaumatin-like protein, ferric reduction oxidase 2 and transcription factor bHLH93. Nine genes which were down-regulated in PUSA362 found to be up-regulated in PUSA372, including glutathione S-transferase like, putative calmodulin-like 19, high affinity nitrate transporter 2.4 and ERF17-like protein. Some important carbohydrate metabolism related genes, like fructose-1,6-bisphosphatase and sucrose synthase, and root growth related Expansin gene were exclusively down-regulated, while an ethylene biosynthesis gene 1-aminocyclopropane-1-carboxylate oxidase 1 (ACO1) was up-regulated in PUSA362. Interplay of these and several other genes related to hormones (auxin, cytokinin, GA etc.), signal transduction components (like CBLs and CIPKs), ion transporters and transcription factors might underlie the contrasting response of two chickpea cultivars to K deficiency. In future, some of these key genes will be utilized in genetic engineering and breeding programs for developing chickpea cultivars with improved K use efficiency (KUE) and K deficiency tolerance traits.
钾（K）是植物生长发育所必需的大量元素。钾缺乏会阻碍重要的植物生理过程，如酶激活、蛋白质合成、光合作用和气孔运动。在模式植物拟南芥中，对钾缺乏耐受性的分子机制已有部分了解，但在豆科作物鹰嘴豆中尚不清楚。在此，形态生理分析表明，在五个高产本地鹰嘴豆品种中，PUSA362在钾缺乏条件下表现出植株生长发育不良、初生根生长受抑制以及钾含量低。相比之下，PUSA372对这些参数的影响可忽略不计，这表明PUSA362对钾缺乏敏感，而PUSA372是耐钾缺乏的鹰嘴豆品种。基于RNA测序的转录组分析显示，在钾缺乏条件下，PUSA362共有820个差异表达基因（DEG），PUSA372有682个DEG。这些DEG属于不同的功能类别，如植物代谢、信号转导成分、转录因子、离子/营养转运蛋白、植物激素生物合成和信号传导以及根的生长发育。通过RT-qPCR验证了随机选择的16个DEG的RNA测序表达。在16个基因中，13个基因的表达模式与RNA测序表达相似，验证了RNA测序表达数据。在PUSA362和PUSA372中，分别有258个和159个基因专门上调，386个和347个基因下调。14个DEG表现出相反的表达模式，它们在PUSA362中上调而在PUSA372中下调。这些基因包括体细胞胚胎发生受体样激酶1、类甜蛋白、铁还原氧化酶2和转录因子bHLH93。在PUSA362中下调而在PUSA372中上调的9个基因，包括谷胱甘肽S-转移酶样、假定的类钙调蛋白19、高亲和力硝酸盐转运蛋白2.4和ERF17样蛋白。一些重要的碳水化合物代谢相关基因，如1,6-二磷酸果糖酶和蔗糖合酶，以及根生长相关的扩展蛋白基因专门下调，而乙烯生物合成基因1-氨基环丙烷-1-羧酸氧化酶1（ACO1）在PUSA362中上调。这些基因以及其他一些与激素（生长素、细胞分裂素、赤霉素等）、信号转导成分（如CBL和CIPK）、离子转运蛋白和转录因子相关的基因之间的相互作用，可能是两个鹰嘴豆品种对钾缺乏产生不同反应的基础。未来，这些关键基因中的一些将用于基因工程和育种计划，以培育具有提高钾利用效率（KUE）和耐钾缺乏性状的鹰嘴豆品种。
