Du Jiujun, Zhou Xinglu, Wei Hantian, Bai Yongxia, Song Xueqin, Zhang Lei, Hu Jianjun
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China; Institute of Millet Crops, Hebei Academy of Agriculture and Forestry Sciences, Key Laboratory of Genetic Improvement and Utilization for Featured Coarse Cereals (Co-Construction By Ministry and Province), Ministry of Agriculture and Rural Affairs, The Key Research Laboratory of Minor Cereal Crops of Hebei Province, Shijiazhuang, Hebei, 050035, China.
State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing, 100091, China; Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, Jiangsu, 210037, China.
Plant Physiol Biochem. 2025 Jul 12;228:110233. doi: 10.1016/j.plaphy.2025.110233.
Proteins belonging to the small GTPases family, particularly Rab proteins, are involved in plant root development. The RabG subfamily proteins, in particular, play a role in regulating plant stress responses. This study revealed that the poplar RabG protein PdRabG3f exhibited tissue-specific activity in root epidermis, root hairs, and vascular stele. Functional characterization further demonstrated that overexpression of PdRabG3f in transgenic poplar significantly inhibited root elongation, reducing maximum root length, and fresh root weight, whereas suppression of PdRabG3f enhanced root growth - a phenotype consistent with its spatial expression pattern. In PdRabG3f overexpression lines, elevated endogenous abscisic acid (ABA) levels were observed, which correlated with enhanced ABA sensitivity and further inhibition of root elongation under exogenous ABA treatment. As a result, these lines exhibited improved resilience under salt stress, including higher peroxidase activity, reduced malondialdehyde content, and maintained relative water content. Transcriptome analysis further supported their enhanced salt tolerance, revealing significant upregulation of stress-responsive genes and enrichment in stress response pathways. These findings establish PdRabG3f as a negative regulator of root growth via ABA biosynthesis and highlight its role in enhancing salt tolerance through ABA-dependent stress signaling. This study provides novel insights into Rab protein-mediated hormonal regulation in woody plants, offering potential targets for improving stress resilience in poplar.
属于小GTP酶家族的蛋白质，特别是Rab蛋白，参与植物根系发育。尤其是RabG亚家族蛋白在调节植物应激反应中发挥作用。本研究表明，杨树RabG蛋白PdRabG3f在根表皮、根毛和维管柱中表现出组织特异性活性。功能特性进一步证明，在转基因杨树中过表达PdRabG3f显著抑制根伸长，降低最大根长和鲜根重量，而抑制PdRabG3f则促进根生长——这一表型与其空间表达模式一致。在PdRabG3f过表达系中，观察到内源脱落酸（ABA）水平升高，这与ABA敏感性增强以及在外源ABA处理下根伸长的进一步抑制相关。因此，这些品系在盐胁迫下表现出更强的恢复力，包括更高的过氧化物酶活性、更低的丙二醛含量以及维持相对含水量。转录组分析进一步支持了它们增强的耐盐性，揭示了应激反应基因的显著上调以及应激反应途径的富集。这些发现确立了PdRabG3f作为通过ABA生物合成调节根生长的负调控因子，并突出了其在通过ABA依赖的应激信号增强耐盐性中的作用。本研究为木本植物中Rab蛋白介导的激素调节提供了新的见解，为提高杨树的应激恢复力提供了潜在靶点。
