Pigeonpea (Cajanus cajan L.) is a rich source of nutritionally good quality proteins, carbohydrates, minerals, and vitamins. However, environmental stresses adversely affect its productivity. Only limited reports are available on biochemical/physiological responses of pigeonpea under salt stress. The objectives of the present study were to screen pigeonpea germplasm accessions for salt stress tolerance, followed by understanding their biochemical, epigenetic and molecular responses. Based on germination, growth, and vigor of seedlings under salt stress, the most contrasting pair of salt-responsive genotypes (ICP1071- most salt-sensitive, and ICP7- most salt-tolerant) were selected. Three-week-old seedlings subjected to 250 mM NaCl stress for 7 days showed a significant increase in proline and reducing sugar contents in the case of ICP7, whereas a considerable increase in cell wall-degrading enzyme activity and protein oxidation was observed in ICP1071. Superoxide dismutase, peroxidase, and glutathione reductase activity increased considerably in shoots of ICP7. We observed the CcCYP gene to be upregulated in root, whereas CcCDR was upregulated in shoots of the salt-tolerant genotype to provide protection against the stress. The extent of DNA hypomethylation in the contrasting pigeonpea genotypes under salt stress was correlated with their salt tolerance level. Bisulfite sequencing of CcCDR revealed that methylation of three cytosine residues in CHH context in shoots of the ICP7 genotype due to salt stress results in 2.6-fold upregulated expression of the gene. With a 6.8% increase in methylation of the coding region of CcCDR, its expression level increased by 22%. To the best of our knowledge, this is the first report on a comprehensive study of salt-induced biochemical, epigenetic and molecular responses of pigeonpea, which might be useful in the development of improved salt-tolerant variety.

中文翻译：

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对盐胁迫诱导的鸽子空间反应的生化、分子和表观遗传调控的见解 (Cajanus cajan L.)

鸽子豌豆 (Cajanus cajan L.) 富含优质蛋白质、碳水化合物、矿物质和维生素。然而，环境压力对其生产力产生不利影响。关于盐胁迫下木豆的生化/生理反应的报道有限。本研究的目的是筛选木豆种质材料的盐胁迫耐受性，然后了解它们的生化、表观遗传和分子反应。根据盐胁迫下幼苗的发芽、生长和活力，选择了最具对比性的一对盐响应基因型（ICP1071-最盐敏感，ICP7-最耐盐）。在 ICP7 的情况下，3 周龄幼苗在 250 mM NaCl 胁迫下 7 天显示脯氨酸和还原糖含量显着增加，而在 ICP1071 中观察到细胞壁降解酶活性和蛋白质氧化的显着增加。超氧化物歧化酶、过氧化物酶和谷胱甘肽还原酶活性在 ICP7 的枝条中显着增加。我们观察到 CcCYP 基因在根中被上调，而 CcCDR 在耐盐基因型的枝条中被上调，以提供对抗胁迫的保护。盐胁迫下对比木豆基因型的 DNA 低甲基化程度与其耐盐水平相关。CcCDR 的亚硫酸氢盐测序显示，由于盐胁迫，ICP7 基因型枝条中 CHH 环境中三个胞嘧啶残基的甲基化导致基因表达上调 2.6 倍。随着 CcCDR 编码区甲基化程度增加 6.8%，其表达水平增加了 22%。