病原体反应性免疫相关基因(抗性基因[R基因])和激素是系统获得性抗性(SAR)的关键介质。然而,它们在调节局部和远端叶片中SAR信号成分方面的综合功能仍然未知。表征油菜黄单胞菌pv中的SAR。油菜花(Xcc)-甘蓝型油菜病态系统,R基因的反应,(叶和韧皮部)激素水平,H2O2水平,在暴露于四种Xcc处理的植物的局部和远端叶片中评估了与Ca2信号相关的基因:非接种(对照),仅在远端叶中进行二次Xcc接种(C-Xcc),仅在局部叶片中进行初级Xcc接种(Xcc),以及初次和二次Xcc接种(X-Xcc)。初次Xcc接种引起疾病症状,如接种后7天Xcc和X-Xcc植物的局部叶片中破坏性坏死扩大所证明。比较二次接种后5天远端叶的视觉症状,在非Xcc引发的植物(C-Xcc)中清楚地观察到淡黄色坏死病变,而在Xcc引发的植物(X-Xcc)中没有出现视觉症状,展示SAR。X-Xcc植物的病原体抗性的特征是PAMP触发的免疫(PTI)相关激酶编码基因的表达明显上调,BIK1,(CC-NB-LRR型)R基因,ZAR1及其信号相关基因,NDR1,随着激酶编码基因的同时增强,MAPK6和(TIR-NB-LRR型)R基因的抑制,TAO1及其信号相关基因,SGT1,在远端叶中。Further,在X-Xcc工厂,较高的水杨酸(SA)和茉莉酸(JA)水平,在韧皮部和远端叶中,伴随着SA信号基因的表达增强,NPR3,JA信号基因,LOX2和PDF1.2,以及Ca2+信号基因,CAS和CBP60g。然而,在C-Xcc植物的远端叶中,SA水平的增加导致了JA的拮抗性抑郁,仅增强SA依赖性信号,EDS1和NPR1。这些结果表明,局部叶片中的初次Xcc接种通过上调BIK1-ZAR1介导的与SA和JA信号作为SAR的关键组成部分的协同相互作用来诱导对随后的病原体攻击的抗性。
Pathogen-responsive immune-related genes (resistance genes [R-genes]) and hormones are crucial mediators of systemic acquired resistance (SAR). However, their integrated functions in regulating SAR signaling components in local and distal leaves remain largely unknown. To characterize SAR in the Xanthomonas campestris pv. campestris (Xcc)-Brassica napus pathosystem, the responses of R-genes, (leaf and phloem) hormone levels, H2O2 levels, and Ca2+ signaling-related genes were assessed in local and distal leaves of plants exposed to four Xcc-treatments: Non-inoculation (control), only secondary Xcc-inoculation in distal leaves (C-Xcc), only primary Xcc-inoculation in local leaves (Xcc), and both primary and secondary Xcc-inoculation (X-Xcc). The primary Xcc-inoculation provoked disease symptoms as evidenced by enlarged destructive necrosis in the local leaves of Xcc and X-Xcc plants 7 days post-inoculation. Comparing visual symptoms in distal leaves 5 days post-secondary inoculation, yellowish necrotic lesions were clearly observed in non Xcc-primed plants (C-Xcc), whereas no visual symptom was developed in Xcc-primed plants (X-Xcc), demonstrating SAR. Pathogen resistance in X-Xcc plants was characterized by distinct upregulations in expression of the PAMP-triggered immunity (PTI)-related kinase-encoding gene, BIK1, the (CC-NB-LRR-type) R-gene, ZAR1, and its signaling-related gene, NDR1, with a concurrent enhancement of the kinase-encoding gene, MAPK6, and a depression of the (TIR-NB-LRR-type) R-gene, TAO1, and its signaling-related gene, SGT1, in distal leaves. Further, in X-Xcc plants, higher salicylic acid (SA) and jasmonic acid (JA) levels, both in phloem and distal leaves, were accompanied by enhanced expressions of the SA-signaling gene, NPR3, the JA-signaling genes, LOX2 and PDF1.2, and the Ca2+-signaling genes, CAS and CBP60g. However, in distal leaves of C-Xcc plants, an increase in SA level resulted in an antagonistic depression of JA, which enhanced only SA-dependent signaling, EDS1 and NPR1. These results demonstrate that primary Xcc-inoculation in local leaves induces resistance to subsequent pathogen attack by upregulating BIK1-ZAR1-mediated synergistic interactions with SA and JA signaling as a crucial component of SAR.