Song Fang, Ji Chuanya, Wang Tingting, Zhang Zelu, Duan Yaoyuan, Yu Miao, Song Xin, Jiang Yingchun, He Ligang, Wang Zhijing, Ma Xiaofang, Zhang Yu, Pan Zhiyong, Wu Liming
Hubei Key Laboratory of Germplasm Innovation and Utilization of Fruit Trees, Institute of Fruit and Tea, Hubei Academy of Agricultural Sciences, Wuhan 430064, China.
Ministry of Education Key Laboratory for Cellular Dynamics, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China.
Int J Mol Sci. 2025 Feb 27;26(5):2082. doi: 10.3390/ijms26052082.
Arbuscular mycorrhizal (AM) fungi establish mutualistic symbiosis with most land plants, facilitating mineral nutrient uptake in exchange for photosynthates. As one of the most commercially used rootstocks in citrus, heavily depends on AM fungi for nutrient absorption. The gene family plays essential roles in plant growth and development, signaling transduction, and responses to biotic and abiotic stresses. However, the identification and functional characterization of family genes in remains largely unexplored. In this study, a comprehensive genome-wide analysis of PtGRAS family genes was conducted, including their identification, physicochemical properties, phylogenetic relationships, gene structures, conserved domains, chromosome localization, and collinear relationships. Additionally, the expression profiles and protein interaction of these genes under AM symbiosis were systematically investigated. As a result, 41 genes were identified in the genome, and classified into nine distinct clades. Collinearity analysis revealed seven segmental duplications but no tandem duplications, suggesting that segmental duplication played a more important role in the expansion of the gene family compared to tandem duplication. Additionally, 18 genes were differentially expressed in response to AM symbiosis, including orthologs of , , and in . Yeast two-hybrid (Y2H) screening further revealed that PtGRAS6 and PtGRAS20 interacted with both PtGRAS12 and PtGRAS18, respectively. The interactions were subsequently validated through bimolecular fluorescence complementation (BiFC) assays. These findings underscored the crucial role of genes in AM symbiosis in , and provided valuable candidate genes for improving nutrient uptake and stress resistance in citrus rootstocks through molecular breeding approaches.
丛枝菌根（AM）真菌与大多数陆地植物建立互利共生关系，促进矿物质养分吸收以换取光合产物。作为柑橘中最常用的砧木之一，其在很大程度上依赖AM真菌进行养分吸收。GRAS基因家族在植物生长发育、信号转导以及对生物和非生物胁迫的响应中发挥着重要作用。然而，柑橘中GRAS家族基因的鉴定和功能表征在很大程度上仍未被探索。在本研究中，对PtGRAS家族基因进行了全面的全基因组分析，包括它们的鉴定、理化性质、系统发育关系、基因结构、保守结构域、染色体定位和共线性关系。此外，还系统地研究了这些基因在AM共生条件下的表达谱和蛋白质相互作用。结果，在柑橘基因组中鉴定出41个GRAS基因，并分为9个不同的进化枝。共线性分析揭示了7个片段重复但没有串联重复，这表明与串联重复相比，片段重复在GRAS基因家族的扩张中发挥了更重要的作用。此外，18个GRAS基因在响应AM共生时差异表达，包括柑橘中LjGRAS1、LjGRAS3和LjGRAS4的直系同源基因。酵母双杂交（Y2H）筛选进一步表明，PtGRAS6和PtGRAS20分别与PtGRAS12和PtGRAS18相互作用。随后通过双分子荧光互补（BiFC）试验验证了这些相互作用。这些发现强调了GRAS基因在柑橘AM共生中的关键作用，并为通过分子育种方法提高柑橘砧木的养分吸收和抗逆性提供了有价值的候选基因。
