PDF(Pubmed)
Abstract：
BACKGROUND: Biological nitrogen fixation (BNF) is an important nitrogen source for legume plants, and highly efficient nitrogen fixation requires sufficient phosphorus (P). However, the mechanism of maintaining nitrogen fixation of the legume nodules under low P concentration remains largely unknown.
RESULTS: A nodule-localized SPX protein, GmSPX8, was discovered by transcriptome and functional analysis of its role in N2 fixation was characterized in soybean nodules. GmSPX8 was preferentially expressed in nodules and its expression was gradually increased during nodule development. And also the expression pattern was investigated using reporter gene β-glucuronidase (GUS) driven by the promoter of GmSPX8. GmSPX8 was greatly induced and the GUS activity was increased by 12.2% under P deficiency. Overexpression of GmSPX8 in transgenic plants resulted in increased nodule number, nodule fresh weight and nitrogenase activity by 15.0%, 16.0%, 42.5%, subsequently leading to increased N and P content by 17.0% and 19.0%, while suppression of GmSPX8 showed significantly impaired nodule development and nitrogen fixation efficiency under low P stress. These data indicated that GmSPX8 conferred nodule development and nitrogen fixation under low P condition. By yeast two-hybrid screening, GmPTF1 was identified as a potential interacting protein of GmSPX8, which was further confirmed by BiFC, Y2H and pull down assay. Transcript accumulation of GmPTF1 and its downstream genes such as GmEXLB1 and EXPB2 were increased in GmSPX8 overexpressed transgenic nodules, and in the presence of GmSPX8, the transcriptional activity of GmPTF1 in yeast cells and tobacco leaves was greatly enhanced.
CONCLUSIONS: In summary, these findings contribute novel insights towards the role of GmSPX8 in nodule development and nitrogen fixation partly through interacting with GmPTF1 in soybean under low P condition.
RESULTS: A nodule-localized SPX protein, GmSPX8, was discovered by transcriptome and functional analysis of its role in N2 fixation was characterized in soybean nodules. GmSPX8 was preferentially expressed in nodules and its expression was gradually increased during nodule development. And also the expression pattern was investigated using reporter gene β-glucuronidase (GUS) driven by the promoter of GmSPX8. GmSPX8 was greatly induced and the GUS activity was increased by 12.2% under P deficiency. Overexpression of GmSPX8 in transgenic plants resulted in increased nodule number, nodule fresh weight and nitrogenase activity by 15.0%, 16.0%, 42.5%, subsequently leading to increased N and P content by 17.0% and 19.0%, while suppression of GmSPX8 showed significantly impaired nodule development and nitrogen fixation efficiency under low P stress. These data indicated that GmSPX8 conferred nodule development and nitrogen fixation under low P condition. By yeast two-hybrid screening, GmPTF1 was identified as a potential interacting protein of GmSPX8, which was further confirmed by BiFC, Y2H and pull down assay. Transcript accumulation of GmPTF1 and its downstream genes such as GmEXLB1 and EXPB2 were increased in GmSPX8 overexpressed transgenic nodules, and in the presence of GmSPX8, the transcriptional activity of GmPTF1 in yeast cells and tobacco leaves was greatly enhanced.
CONCLUSIONS: In summary, these findings contribute novel insights towards the role of GmSPX8 in nodule development and nitrogen fixation partly through interacting with GmPTF1 in soybean under low P condition.
摘要：
背景：生物固氮（BNF）是豆科植物的重要氮源，高效固氮需要足够的磷(P)。然而,在低磷浓度下保持豆类结节固氮的机制仍然未知。
结果：结节定位的SPX蛋白，通过转录组发现了GmSPX8，并在大豆结节中表征了其在N2固定中的作用。GmSPX8在结节中优先表达，其表达在结节发育过程中逐渐增加。并且还使用由GmSPX8的启动子驱动的报告基因β-葡糖醛酸糖苷酶（GUS）研究了表达模式。在缺乏磷的情况下，GmSPX8被显著诱导，GUS活性增加12.2%。转基因植物中GmSPX8的过表达导致结节数量增加，结节鲜重和固氮酶活性降低15.0%，16.0%,42.5%,随后导致N和P含量增加17.0%和19.0%，而抑制GmSPX8在低磷胁迫下显示出显着损害的结节发育和固氮效率。这些数据表明GmSPX8在低磷条件下赋予结节发育和固氮。通过酵母双杂交筛选,GmPTF1被鉴定为GmSPX8的潜在相互作用蛋白，并被BiFC进一步证实。Y2H和下拉测定。在GmSPX8过表达的转基因结节中，GmPTF1及其下游基因如GmEXLB1和EXPB2的转录积累增加，而在GmSPX8的存在下，GmPTF1在酵母细胞和烟草叶片中的转录活性获得了极年夜的加强。
结论：总之，这些发现为GmSPX8在低磷条件下大豆根瘤发育和固氮中的作用提供了新的见解，部分是通过与GmPTF1相互作用。
结果：结节定位的SPX蛋白，通过转录组发现了GmSPX8，并在大豆结节中表征了其在N2固定中的作用。GmSPX8在结节中优先表达，其表达在结节发育过程中逐渐增加。并且还使用由GmSPX8的启动子驱动的报告基因β-葡糖醛酸糖苷酶（GUS）研究了表达模式。在缺乏磷的情况下，GmSPX8被显著诱导，GUS活性增加12.2%。转基因植物中GmSPX8的过表达导致结节数量增加，结节鲜重和固氮酶活性降低15.0%，16.0%,42.5%,随后导致N和P含量增加17.0%和19.0%，而抑制GmSPX8在低磷胁迫下显示出显着损害的结节发育和固氮效率。这些数据表明GmSPX8在低磷条件下赋予结节发育和固氮。通过酵母双杂交筛选,GmPTF1被鉴定为GmSPX8的潜在相互作用蛋白，并被BiFC进一步证实。Y2H和下拉测定。在GmSPX8过表达的转基因结节中，GmPTF1及其下游基因如GmEXLB1和EXPB2的转录积累增加，而在GmSPX8的存在下，GmPTF1在酵母细胞和烟草叶片中的转录活性获得了极年夜的加强。
结论：总之，这些发现为GmSPX8在低磷条件下大豆根瘤发育和固氮中的作用提供了新的见解，部分是通过与GmPTF1相互作用。
