Chen Tao, Bi Kai, He Zhangchao, Gao Zhixiao, Zhao Ying, Fu Yanping, Cheng Jiasen, Xie Jiatao, Jiang Daohong
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural UniversityWuhan, China; The Provincial Key Lab of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural UniversityWuhan, China.
Front Physiol. 2016 Sep 13;7:402. doi: 10.3389/fphys.2016.00402. eCollection 2016.
Botrytis-induced kinase1 (BIK1), a receptor-like cytoplasmic kinase, plays an important role in resistance against pathogens and insects in Arabidopsis thaliana. However, it remains unknown whether BIK1 functions against Plasmodiophora brassicae, an obligate biotrophic protist that attacks cruciferous plants and induces gall formation on roots. Here, we investigated the potential roles of receptors FLS2, BAK1, and BIK1 in the infection of P. brassicae cruciferous plants. Wild-type plants, fls2, and bak1 mutants showed typical symptom on roots, and the galls were filled with large quantities of resting spores, while bik1 mutant plants exhibited strong resistance to P. brassicae. Compared with that of the wild-type plants, the root hair and cortical infection rate of bik1 mutant were significantly reduced by about 40-50%. A considerable portion of bik1 roots failed to form typical galls. Even if some small galls were formed, they were filled with multinucleate secondary plasmodia. The bik1 plants accumulated less reactive oxygen species (ROS) at infected roots than other mutants and wild-type plants. Exogenous salicylic acid (SA) treatment alleviated the clubroot symptoms in wild-type plants, and the expression of the SA signaling marker gene PR1 was significantly increased in bik1. Both sid2 (salicylic acid induction-deficient 2) and npr1-1 [non-expresser of PR genes that regulate systemic acquired resistance (SAR)] mutants showed increased susceptibility to P. brassicae compared with wild-type plants. These results suggest that the resistance of bik1 to P. brassicae is possibly mediated by SA inducible mechanisms.
灰霉病菌诱导激酶1（BIK1）是一种类受体细胞质激酶，在拟南芥对病原体和昆虫的抗性中发挥重要作用。然而，BIK1是否在芸苔根肿菌（一种专性活体营养型原生生物，侵袭十字花科植物并在根部诱导形成根肿）的抗性中发挥作用仍不清楚。在此，我们研究了受体FLS2、BAK1和BIK1在芸苔根肿菌侵染十字花科植物中的潜在作用。野生型植物、fls2和bak1突变体在根部表现出典型症状，根肿中充满大量休眠孢子，而bik1突变体植物对芸苔根肿菌表现出较强抗性。与野生型植物相比，bik1突变体的根毛和皮层感染率显著降低约40 - 50%。相当一部分bik1的根未能形成典型根肿。即使形成了一些小根肿，其中也充满了多核次生原质团。bik1植株在受侵染的根部积累的活性氧（ROS）比其他突变体和野生型植物少。外源水杨酸（SA）处理减轻了野生型植物的根肿症状，且SA信号标记基因PR1在bik1中的表达显著增加。与野生型植物相比，sid2（水杨酸诱导缺陷2）和npr1 - 1[调节系统获得性抗性（SAR）的PR基因非表达者]突变体对芸苔根肿菌的易感性增加。这些结果表明，bik1对芸苔根肿菌的抗性可能由SA诱导机制介导。
