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Luo Y, Liu D, Jiao S, Liu S, Wang X, Shen X, Wei G. Identification of Robinia pseudoacacia target proteins responsive to Mesorhizobium amphore CCNWGS0123 effector protein NopT. JOURNAL OF EXPERIMENTAL BOTANY 2020; 71:7347-7363. [PMID: 32865563 DOI: 10.1093/jxb/eraa405] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 08/28/2020] [Indexed: 06/11/2023]
Abstract
Nodulation outer proteins secreted via type 3 secretion systems are involved in the process of symbiosis between legume plants and rhizobia. To study the function of NopT in symbiosis, we mutated nopT in Mesorhizobium amphore CCNWGS0123 (GS0123), which can nodulate black locust (Robinia pseudoacacia). The nopT mutant induced higher levels of jasmonic acid, salicylic acid, and hydrogen peroxide accumulation in the roots of R. pseudoacacia compared with wild-type GS0123. The ΔnopT mutant induced higher disease-resistant gene expression 72 hours post-inoculation (hpi), whereas GS0123 induced higher disease-resistant gene expression earlier, at 36 hpi. Compared with the nopT mutant, GS0123 induced the up-regulation of most genes at 36 hpi and the down-regulation of most genes at 72 hpi. Proteolytically active NopT_GS0123 induced hypersensitive responses when expressed transiently in tobacco leaves (Nicotiana benthamiana). Two NopT_GS0123 targets in R. pseudoacacia were identified, ATP-citrate synthase alpha chain protein 2 and hypersensitive-induced response protein. Their interactions with NopT_GS0123 triggered resistance by the plant immune system. In conclusion, NopT_GS0123 inhibited the host plant immune system and had minimal effect on nodulation in R. pseudoacacia. Our results reveal the underlying molecular mechanism of NopT function in plant-symbiont interactions.
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Affiliation(s)
- Yantao Luo
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Dongying Liu
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Shuo Jiao
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Shuang Liu
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Xinye Wang
- Department of Liquor Making Engineering, Moutai College, Renhuai, China
| | - Xihui Shen
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
| | - Gehong Wei
- State Key Laboratory of Crop Stress Biology in Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Sciences, Northwest A & F University, Yangling, Shaanxi, China
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Wang X, Huo H, Luo Y, Liu D, Zhao L, Zong L, Chou M, Chen J, Wei G. Type III secretion systems impact Mesorhizobium amorphae CCNWGS0123 compatibility with Robinia pseudoacacia. TREE PHYSIOLOGY 2019; 39:1533-1550. [PMID: 31274160 DOI: 10.1093/treephys/tpz077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 06/26/2018] [Accepted: 06/18/2019] [Indexed: 06/09/2023]
Abstract
Rhizobia and legume plants are famous mutualistic symbiosis partners who provide nitrogen nutrition to the natural environment. Rhizobial type III secretion systems (T3SSs) deliver effectors that manipulate the metabolism of eukaryotic host cells. Mesorhizobium amorphae CCNWGS0123 (GS0123) contains two T3SS gene clusters, T3SS-I and T3SS-II. T3SS-I contains all the basal components for an integrated T3SS, and the expression of T3SS-I genes is up-regulated in the presence of flavonoids. In contrast, T3SS-II lacks the primary extracellular elements of T3SSs, and the expression of T3SS-II genes is down-regulated in the presence of flavonoids. Inoculation tests on Robinia pseudoacacia displayed considerable differences in gene expression patterns and levels among roots inoculated with GS0123 and T3SS-deficient mutant (GS0123ΔrhcN1 (GS0123ΔT1), GS0123ΔrhcN2 (GS0123ΔT2) and GS0123ΔrhcN1ΔrhcN2 (GS0123ΔS)). Compared with the GS0123-inoculated plants, GS0123ΔT1-inoculated roots formed very few infection threads and effective nodules, while GS0123ΔT2-inoculated roots formed a little fewer infection threads and effective nodules with increased numbers of bacteroids enclosed in one symbiosome. Moreover, almost no infection threads or effective nodules were observed in GS0123ΔS-inoculated roots. In addition to evaluations of plant immunity signals, we observed that the coexistence of T3SS-I and T3SS-II promoted infection by suppressing host defense response in the reactive oxygen species defense response pathway. Future studies should focus on identifying rhizobial T3SS effectors and their host target proteins.
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Affiliation(s)
- Xinye Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Haibo Huo
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Yantao Luo
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Dongying Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Liang Zhao
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Le Zong
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Minxia Chou
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Juan Chen
- State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
| | - Gehong Wei
- State Key Laboratory of Crop Stress Biology for Arid Areas, Shaanxi Key Laboratory of Agricultural and Environmental Microbiology, College of Life Science, Northwest A&F University, Yangling, Shaanxi, People's Republic of China
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