Table_1_Morphophysiological and transcriptome analysis reveal that reprogramming of metabolism, phytohormones and root development pathways governs the potassium (K+) deficiency response in two contrasting chickpea cultivars.xlsx

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.

钾离子（K+）是植物生长与发育的必需大量营养素。K+的缺乏会阻碍诸如酶活化、蛋白质合成、光合作用以及气孔运动等重要植物过程。在模式植物拟南芥中，对K+缺乏耐受性的分子机制已有部分认识，但在豆科作物鹰嘴豆中的相关知识尚属空白。在本研究中，通过对五种高产Desi鹰嘴豆品种的形态生理分析发现，在K+缺乏条件下，PUSA362品种表现出植株生长迟缓、主根生长减少以及低K+含量。相比之下，PUSA372品种对这些参数的影响微乎其微，这表明PUSA362对K+缺乏敏感，而PUSA372则是一种对K+缺乏具有耐受性的鹰嘴豆品种。基于RNA测序的转录组分析揭示了PUSA362中存在820个差异表达基因（DEGs），而在PUSA372中存在682个DEGs。这些DEGs隶属于不同的功能类别，例如植物代谢、信号转导组分、转录因子、离子/营养物质转运蛋白、植物激素的生物合成与信号转导，以及根的生长与发育。对随机选择的16个DEGs的RNA测序表达数据进行验证，结果显示，其中13个基因的表达模式与RNA测序表达相似，从而验证了RNA测序数据的准确性。在PUSA362和PUSA372中，分别有258个和159个基因特异性上调，而386个和347个基因特异性下调。14个DEGs表现出相反的表达模式，它们在PUSA362中上调，而在PUSA372中下调，包括体细胞胚胎发生受体样激酶1、类天冬氨酸蛋白、铁还原氧化酶2和转录因子bHLH93。在PUSA362中下调的9个基因在PUSA372中上调，包括类似谷胱甘肽转移酶、假定的钙调蛋白样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，如果糖-1,6-二磷酸酶和蔗糖合酶，以及与根生长相关的 expansin 基因被特异性下调，而一个乙烯生物合成基因1-氨基环丙烷-1-羧酸氧化酶1（ACO1）在PUSA362中上调。这些基因与激素（如生长素、细胞分裂素、GA等）、信号转导组分（如CBLs和CIPKs）、离子转运蛋白和转录因子的相互作用，可能构成了两种鹰嘴豆品种对K+缺乏产生相反反应的分子基础。未来，这些关键基因将被用于遗传工程和育种计划中，以培育具有改进的K+利用效率（KUE）和K+缺乏耐受性状的鹰嘴豆品种。