Wang Xiang, Gong Qichang, Cheng Shengyang, Qin Ning, Cao Tao, Chen Yue, Wang Dongdong, Valls Marc, Coll Núria S, Chen Qin, Zhao Cuizhu, Lu Haibin
State Key Laboratory of Crop Stress Resistance and High-Efficiency Production, College of Agronomy, Northwest A&F University, Yangling, China.
Centre for Research in Agricultural Genomics (CRAG), CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, Barcelona, Spain.
Mol Plant Pathol. 2024 Dec;25(12):e70045. doi: 10.1111/mpp.70045.
Cytokinin signalling plays both positive and negative roles in plant resistance to pathogens. It is not clear whether the role of cytokinin changes at the different stages of pathogen infection. Arabidopsis thaliana sequentially exhibits distinct root morphological symptoms during Ralstonia solanacearum infection, which offers a good system to investigate function of cytokinin in the whole pathogen infection process. Using this system, we found increase of cytokinin signalling by Lonely Guy 2 (LOG2) overexpression or depletion of type-A Arabidopsis Response Regulators (ARRs), negative regulators of cytokinin signalling pathway, promoted cell death, wilting symptom and bacterial growth, but attenuated primary root growth inhibition and lateral root formation. The decrease of cytokinin signalling by mutation on Isopentenyl Transferases (IPTs) inhibited root hair formation, cell death, wilting symptom and bacterial colonisation. Application of different concentration of exogenesis 6-benzylaminopurine (6-BA) showed first promoted, then decreased root hair formation. Moreover, application of 6-BA accelerated cell death but suppressed lateral root formation and primary root growth inhibition. The diverse roles of cytokinin in these different root disease phenotypes suggested function of cytokinin during plant responses to R. solanacearum is cell type-specific, which provides new insights on roles of cytokinin signalling in regulation on plant-pathogen interactions.
细胞分裂素信号传导在植物对病原体的抗性中发挥着正负两方面的作用。尚不清楚细胞分裂素的作用在病原体感染的不同阶段是否会发生变化。在青枯雷尔氏菌感染期间，拟南芥会依次表现出明显的根部形态症状，这为研究细胞分裂素在整个病原体感染过程中的功能提供了一个良好的系统。利用这个系统，我们发现通过过表达孤独基因2（LOG2）或敲除细胞分裂素信号通路的负调控因子A型拟南芥反应调节因子（ARRs）来增强细胞分裂素信号传导，会促进细胞死亡、萎蔫症状和细菌生长，但会减弱主根生长抑制和侧根形成。通过异戊烯基转移酶（IPTs）突变降低细胞分裂素信号传导会抑制根毛形成、细胞死亡、萎蔫症状和细菌定殖。施用不同浓度的外源6-苄基腺嘌呤（6-BA）显示，先是促进，然后降低根毛形成。此外，施用6-BA会加速细胞死亡，但会抑制侧根形成和主根生长抑制。细胞分裂素在这些不同的根部病害表型中的多种作用表明，细胞分裂素在植物对青枯雷尔氏菌的反应过程中的功能具有细胞类型特异性，这为细胞分裂素信号传导在调节植物-病原体相互作用中的作用提供了新的见解。
