Zheng Zhao, Ke Wenjing, Liu Chuanliang, Cai Haomin, Zhu Danting, Liu Qingren, Ji Chuhan, Feng Lei, Gu Jun, Huang Jilei, Wan Xiaorong, Zheng Yixiong, Gao Caiji
Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, School of Life Sciences, South China Normal University, Guangzhou, China.
Instrumental Analysis & Research Center, South China Agricultural University, Guangzhou, China.
Physiol Plant. 2025 Jul-Aug;177(4):e70409. doi: 10.1111/ppl.70409.
Arachis hypogaea (peanut) is an important leguminous crop that obtains nitrogen through symbiotic nitrogen fixation with rhizobia, with root nodules serving as the site of this symbiosis. Although the cytological characteristics and ultrastructure of root nodules in model leguminous plants have been well elucidated, research progress on peanut root nodules remains relatively limited. In this study, we characterized the spatiotemporal developmental pattern of peanut root nodules through microscopic imaging and ultrastructural analysis. Furthermore, we isolated symbiosome-enriched fractions from peanut nodules for proteomic analysis and identified 340 and 182 peanut proteins in a comprehensive proteome atlas of the peanut symbiosome membrane (SM) and peribacteroid space (PBS), respectively. Notably, our analysis revealed a significant enrichment of endosomal regulators in the SM and CAP family proteins (cysteine-rich secretory proteins, antigen 5, and pathogenesis-related 1 proteins) in the PBS. Finally, we demonstrated that AhCAP21 specifically localizes to the symbiosome, and the SM-localized AhRabA2a is essential for proper symbiosome development. Together, these findings advance our understanding of peanut nodule development and provide insights into the protein compositions and regulators in symbiosome biogenesis in peanut nodules.
花生是一种重要的豆科作物，它通过与根瘤菌的共生固氮作用获取氮，根瘤是这种共生关系的发生部位。尽管模式豆科植物根瘤的细胞学特征和超微结构已得到充分阐明，但花生根瘤的研究进展仍然相对有限。在本研究中，我们通过显微镜成像和超微结构分析对花生根瘤的时空发育模式进行了表征。此外，我们从花生根瘤中分离出富含共生体的组分进行蛋白质组学分析，在花生共生体膜（SM）和类菌体周空间（PBS）的综合蛋白质组图谱中分别鉴定出340种和182种花生蛋白。值得注意的是，我们的分析显示内体调节因子在SM中显著富集，而CAP家族蛋白（富含半胱氨酸的分泌蛋白、抗原5和病程相关蛋白1）在PBS中显著富集。最后，我们证明AhCAP21特异性定位于共生体，而定位在SM上的AhRabA2a对共生体的正常发育至关重要。这些发现共同增进了我们对花生根瘤发育的理解，并为花生根瘤共生体生物发生中的蛋白质组成和调节因子提供了见解。
