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Abstract
Microbes possess conserved microbe-associated molecular patterns (MAMPs) that are recognized by plant receptors to induce pattern-triggered immunity (PTI). Despite containing the same MAMPs as pathogens, commensals thrive in the plant rhizosphere microbiome, indicating they must suppress or evade host immunity. Previous work found that bacterial-secreted gluconic acid is sufficient to suppress PTI. Here, we show that gluconic acid biosynthesis is not necessary for immunity suppression by the beneficial bacterial strain Pseudomonas simiae WCS417. We performed a forward genetic screen with EMS-mutagenized P. simiae WCS417 and a flagellin-inducible CYP71A12pro:GUS reporter as a PTI readout. We identified a loss of function mutant in ornithine carbamoyltransferase argF, which is required for ornithine conversion to arginine, that cannot suppress PTI or acidify the rhizosphere. Fungal pathogens use alkalization through production of ammonia and glutamate, and arginine biosynthetic precursors, to promote their own growth and virulence. While a ΔargF mutant has a growth defect in the rhizosphere, we found that restoring growth with exogenous arginine resulted in rhizosphere alkalization in a mutant that cannot make gluconic acid, indicating that arginine biosynthesis is required for both growth and acidification. Furthermore, blocking bacterial arginine, glutamine, or proline biosynthesis through genetic mutations or feedback inhibition by adding corresponding amino acids, resulted in rhizosphere alkalization. Untargeted metabolomics determined that ornithine, an alkaline molecule, accumulates under conditions associated with rhizosphere alkalization. Our findings show that bacterial amino acid biosynthesis contributes to acidification by preventing accumulation of ornithine and the resulting alkalization. IMPORTANCE Understanding how microbiota evade and suppress host immunity is critical to our knowledge of how beneficial microbes persist in association with a host. Prior work has shown that secretion of organic acids by beneficial microbes is sufficient to suppress plant immunity. This work shows that microbial amino acid metabolism is not only critical for growth in the plant rhizosphere microbiome, but also for regulation of plant rhizosphere pH, and, consequentially, regulation of plant immunity. We found that, in the absence of microbial glutamate and arginine metabolism, rhizosphere alkalization and microbial overgrowth occurs. Collectively, our findings suggest that, by regulating nutrient availability, plants have the potential to regulate their immune homeostasis in the rhizosphere microbiome.
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Luo X, Wang L, Fu Y, Liu Q, Chen G, Liu Y, He W, Gao A, Xu J, Deng H, Xing J. FERONIA-like receptor 1-mediated calcium ion homeostasis is involved in the immune response. FRONTIERS IN PLANT SCIENCE 2022; 13:934195. [PMID: 36212313 PMCID: PMC9539441 DOI: 10.3389/fpls.2022.934195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Accepted: 07/15/2022] [Indexed: 06/16/2023]
Abstract
Calcium (Ca2+) is the most abundant divalent cation in plants, and cellular levels of Ca2+, which functions as a nutrient and secondary messenger, play a critical role in plant immunity. In the present study, we found that FERONIA-like receptor 1 (FLR1) positively regulates Magnaporthe oryzae resistance and that expression of FLR1 is strongly induced in response to Ca2+ deficiency. In addition, the Ca content in the shoots of flr1 was lower than that in wild-type, and the M. oryzae-sensitive phenotype of the flr1 mutant was not rescued by exogenous application of Ca2+. Moreover, RNA sequencing revealed 2,697 differentially expressed genes (DEGs) in the flr1 mutant compared with wild-type, and some of these DEGs are involved in cellular metal ion homeostasis and transition metal ion homeostasis. Changes in expression of overlapping genes between the flr1 mutant and in plants under low-Ca2+ treatment were consistent in terms of direction, indicating that FLR1 is involved in Ca2+ homeostasis. In summary, we detected FLR1-mediated resistance to M. oryzae, a phenomenon associated with Ca2+ homeostasis.
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Affiliation(s)
- Xiao Luo
- College of Biology, Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, China
- State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Crops Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Long Wang
- College of Biology, Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, China
- State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Crops Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Yuefeng Fu
- Yueyang Academy of Agricultural Sciences, Yueyang, China
| | - Qiqi Liu
- Yueyang Academy of Agricultural Sciences, Yueyang, China
| | - Ge Chen
- Yueyang Academy of Agricultural Sciences, Yueyang, China
| | - Yue Liu
- College of Biology, Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, China
- State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Crops Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Wei He
- College of Biology, Hunan Key Laboratory of Plant Functional Genomics and Developmental Regulation, Hunan University, Changsha, China
| | - Aijun Gao
- State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Crops Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Jingbo Xu
- State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Crops Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Huafeng Deng
- State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Crops Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
| | - Junjie Xing
- State Key Laboratory of Hybrid Rice, Hunan Hybrid Rice Research Center, Crops Research Institute, Hunan Academy of Agricultural Sciences, Changsha, China
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Gao Y, Xiong X, Wang H, Wang J, Bi Y, Yan Y, Cao Z, Li D, Song F. Ero1-Pdi1 module-catalysed dimerization of a nucleotide sugar transporter, FonNst2, regulates virulence of Fusarium oxysporum on watermelon. Environ Microbiol 2021; 24:1200-1220. [PMID: 34587346 DOI: 10.1111/1462-2920.15789] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 09/23/2021] [Indexed: 11/29/2022]
Abstract
Fusarium oxysporum f. sp. niveum (Fon) is a soil-borne fungus causing vascular Fusarium wilt on watermelon; however, the molecular network regulating Fon virulence remains to be elucidated. Here, we report the function and mechanism of nucleotide sugar transporters (Nsts) in Fon. Fon genome harbours nine FonNst genes with distinct functions in vegetative growth, asexual production, cell wall stress response and virulence. FonNst2 and FonNst3 are required for full virulence of Fon on watermelon and FonNst2 is mainly involved in fungal colonization of the plant tissues. FonNst2 and FonNst3 form homo- or hetero-dimers but function independently in Fon virulence. FonNst2, which has UDP-galactose transporter activity in yeast, interacts with FonEro1 and FonPdi1, both of which are required for full virulence of Fon. FonNst2, FonPdi1 and FonEro1 target to endoplasmic reticulum (ER) and are essential for ER homeostasis and function. FonEro1-FonPdi1 module catalyses the dimerization of FonNst2, which is critical for Fon virulence. Undimerized FonNst2 is unstable and degraded via ER-associated protein degradation in vivo. These data demonstrate that FonEro1-FonPdi1 module-catalysed dimerization of FonNst2 is critical for Fon virulence on watermelon and provide new insights into the regulation of virulence in plant fungal pathogens via disulfide bond formation of key pathogenicity factors.
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Affiliation(s)
- Yizhou Gao
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Xiaohui Xiong
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Hui Wang
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Jiajing Wang
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yan Bi
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Yuqing Yan
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Zhongye Cao
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Dayong Li
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
| | - Fengming Song
- State Key Laboratory of Rice Biology and Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Institute of Biotechnology, Zhejiang University, Hangzhou, 310058, China
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