Wang Xin, Hu Han, Li Fang, Yang Bingxian, Komatsu Setsuko, Zhou Shunli
College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China.
College of Life Sciences and Medicine, Zhejiang Sci-Tech University, Hangzhou 310018, China.
J Proteomics. 2021 Jan 6;230:103999. doi: 10.1016/j.jprot.2020.103999. Epub 2020 Oct 3.
To reveal calcium-mediated germination in soybean, a gel-free/label-free proteomics was performed in radicle of seed imbibed with CaCl. Morphological analysis presented promoting and suppressing performance of seed growth under 5 and 50 mM CaCl, respectively. A total of 106 and 581 proteins were identified in response to 5 and 50 mM CaCl, respectively. Among 33 proteins, which were simultaneously affected by 5 and 50 mM CaCl imbibition, proteins related to protein metabolism, cell, development, and stress showed reversed abundance in response to CaCl on dose-dependent manner. Notably, protein abundance of late embryogenesis abundant (LEA) 4-5, LEA4, and dehydrin decreased and increased by 5 and 50 mM CaCl, respectively, consistent with the transcript level. Moreover, inhibited biosynthesis of gibberellic acid repressed growth of 5 mM CaCl-imbibed soybean, while inhibition of abscisic acid biosynthesis released the suppressing effects of 50 mM CaCl. Taken together, these results suggest that decreased or increased protein abundance of LEA4-5, LEA4, and dehydrin might determine promoting or suppressing effects of low or high level of calcium on soybean through enhancing seed sensitivity to gibberellic acid or abscisic acid during radicle protrusion. SIGNIFICANCE: Calcium serves as a versatile signal in plant growth; however, calcium-mediated germination on dose-dependent manner remains elusive. In this study, dual effects of calcium on radicle protrusion in soybean were investigated using proteomic approach. Radicle growth of germinating seed was improved by 5 mM CaCl; however, it was retarded by 50 mM CaCl. Late embryogenesis abundant (LEA) 4-5, LEA4, and dehydrin displayed converse profiles in response to low and high concentrations of CaCl at both protein abundance and gene expression level. Inhibited biosynthesis of gibberellic acid (GA) significantly impeded radicle protrusion in presence of low concentration of CaCl, while inhibiting of abscisic acid (ABA) biosynthesis released suppression induced by high concentration of CaCl. These findings suggest that LEA proteins are associated with calcium-mediated radicle protrusion on dose-dependent manner, and seed sensitivity to GA and ABA might determine promoting and suppressing effects of calcium on radicle protrusion in soybean.
为揭示大豆中钙介导的种子萌发过程，我们对用氯化钙浸泡的种子胚根进行了无凝胶/无标记蛋白质组学分析。形态学分析表明，5 mM和50 mM氯化钙分别对种子生长有促进和抑制作用。分别鉴定出106种和581种响应5 mM和50 mM氯化钙的蛋白质。在33种同时受5 mM和50 mM氯化钙浸泡影响的蛋白质中，与蛋白质代谢、细胞、发育和胁迫相关的蛋白质，其丰度随氯化钙浓度的增加呈剂量依赖性反向变化。值得注意的是，晚期胚胎丰富蛋白（LEA）4-5、LEA4和脱水素的蛋白质丰度，在5 mM氯化钙处理下降低，而在50 mM氯化钙处理下升高，这与转录水平一致。此外，抑制赤霉素生物合成会抑制5 mM氯化钙浸泡的大豆的生长，而抑制脱落酸生物合成则会解除50 mM氯化钙的抑制作用。综上所述，这些结果表明，LEA4-5、LEA4和脱水素蛋白质丰度的降低或增加，可能通过在胚根突出过程中增强种子对赤霉素或脱落酸的敏感性，来决定低钙或高钙水平对大豆的促进或抑制作用。
钙在植物生长中作为一种多功能信号；然而，钙以剂量依赖方式介导的种子萌发过程仍不清楚。在本研究中，我们使用蛋白质组学方法研究了钙对大豆胚根突出的双重影响。5 mM氯化钙促进了萌发种子的胚根生长；然而，50 mM氯化钙则抑制了胚根生长。晚期胚胎丰富蛋白（LEA）4-5、LEA4和脱水素在蛋白质丰度和基因表达水平上，对低浓度和高浓度氯化钙的反应呈现相反的模式。抑制赤霉素（GA）生物合成显著阻碍了低浓度氯化钙存在下的胚根突出，而抑制脱落酸（ABA）生物合成则解除了高浓度氯化钙诱导的抑制作用。这些发现表明，LEA蛋白与钙介导的胚根突出呈剂量依赖关系，种子对GA和ABA的敏感性可能决定了钙对大豆胚根突出的促进和抑制作用。
