Xu Yunjian, Liu Fang, Wu Fulang, Zou Ruifan, Zhao Manli, Wu Jianping, Cheng Beijiu, Li Xiaoyu
National Engineering Laboratory of Crop Stress Resistance Breeding, Anhui Agricultural University, Hefei 230036, China.
Ministry of Education Key Laboratory for Transboundary Ecosecurity of Southwest China, Yunnan Key Laboratory of Plant Reproductive Adaptation and Evolutionary Ecology and Centre for Invasion Biology, Institute of Biodiversity, School of Ecology and Environmental Science, Yunnan University, Kunming 650504, Yunnan, China.
Plant Physiol. 2024 Dec 2;196(4):2905-2917. doi: 10.1093/plphys/kiae487.
In arbuscular mycorrhizal (AM) symbiosis, appropriate regulation of the formation, maintenance, and degeneration of the arbuscule is essential for plants and fungi. In this study, we identified a Cysteine-2/Histidine-2 zinc finger protein (C2H2-ZFP)-encoding gene in Lotus japonicus named Regulator of Symbiosome Differentiation-Like (LjRSDL) that is required for arbuscule degeneration. Evolutionary analysis showed that homologs of LjRSDL exist in mycorrhizal flowering plants. We obtained ProLjRSDL::GUS transgenic hairy roots and showed that LjRSDL was strongly upregulated upon AM colonization, particularly at 18 days post-AM fungi inoculation and specifically expressed in arbuscule-containing cells. The mycorrhization rate increased in the ljrsdl mutant but decreased in LjRSDL-overexpressed L. japonicus. Interestingly, we observed higher proportions of large arbuscule in the ljrsdl mutant but lower proportions of larger arbuscule in LjRSDL-overexpressing plants. Transcriptome analyses indicated that genes involved in arbuscule degeneration were significantly changed upon the dysregulation of LjRSDL and that LjRSDL-dependent regulation in AM symbiosis is mainly via the hormone signal transduction pathway. LjRSDL, therefore, represents a C2H2-ZFP that negatively regulates AM symbiosis. Our study provides insight into understanding plant-AM fungal communication and AM symbiosis development.
在丛枝菌根（AM）共生中，对丛枝的形成、维持和退化进行适当调控对植物和真菌至关重要。在本研究中，我们在百脉根中鉴定出一个编码半胱氨酸-2/组氨酸-2锌指蛋白（C2H2-ZFP）的基因，命名为类共生体分化调节因子（LjRSDL），它是丛枝退化所必需的。进化分析表明，LjRSDL的同源物存在于菌根开花植物中。我们获得了ProLjRSDL::GUS转基因毛状根，并表明LjRSDL在AM定殖后强烈上调，特别是在接种AM真菌后18天，且在含有丛枝的细胞中特异性表达。Ljrsdl突变体的菌根化率增加，而LjRSDL过表达的百脉根中菌根化率降低。有趣的是，我们在Ljrsdl突变体中观察到较大丛枝的比例较高，而在LjRSDL过表达植物中较大丛枝的比例较低。转录组分析表明，LjRSDL失调后，参与丛枝退化的基因发生了显著变化，并且AM共生中LjRSDL依赖的调控主要通过激素信号转导途径。因此，LjRSDL代表一种对AM共生起负调控作用的C2H2-ZFP。我们的研究为理解植物与AM真菌的交流以及AM共生发育提供了见解。
