The fungal pathogen Sclerotinia sclerotiorum Libert causes rot diseases on many crops worldwide and large economic losses occur frequently because of a lack of resistant varieties. The pathogenesis of S. sclerotiorum ...The fungal pathogen Sclerotinia sclerotiorum Libert causes rot diseases on many crops worldwide and large economic losses occur frequently because of a lack of resistant varieties. The pathogenesis of S. sclerotiorum and the molecular basis of plant responses to the pathogen are poorly understood. In the present investigation, the process of S. sclerotiorum infection in Arabidopsis thaliana L., a plant that is highly susceptible to this fungus, was analysed. In addition, the defense activation in the host was investigated. A convenient inoculation method using millet grain was developed for S. sclerotiorum in Arabidopsis. The fungus rapidly infected the plants, probably through ball- or cushion-like infection structures. Visible symptoms developed within 24 h and plants were killed 72 h after inoculation. Cellulase, the main enzyme that caused host tissues to rot, was secreted by S. sclerotiorum in a pH-dependent manner. Oxalic acid, another pathogenic factor secreted by the fungus, induced necrotic lesions on the leaves, infection with S. sclerotiorum strongly induced the production of the pathogenesis-related （PR） proteins β-1,3-glucanase and chitinase in Arabidopsis. Furthermore, the PR gene PDF. 1 was induced, but not PR1, indicating that the pathogen activated basal defense of jasmonic acid/ethylene dependence, which is consistent with its necrotrophic characteristics. This pathosystem for Arabidopsis-S. sclerotiorum could provide an approach for the analysis of the interactions between S. sclerotiorum and other crops, thereby facilitating genetic manipulation techniques for controlling this pathogen.展开更多
Soybean cyst nematode Heterodera glycines is one of the most serious soil-borne pathogens in soybean production. However, the researches were limited in China due to lack of an effective pathosystem. In this study, we...Soybean cyst nematode Heterodera glycines is one of the most serious soil-borne pathogens in soybean production. However, the researches were limited in China due to lack of an effective pathosystem. In this study, we screened 21 legume Medicago plants in both Medicago truncatula and Medicago sativa to obtain candidate model plants for establishing a new pathosystem for legume-H. glycines interactions. The nematode infection of tested plants was assayed with Race 3 and 4 respectively, which were two dominant H. glycines inbred races in China soybean producing areas. The results showed that the model legume plant M. truncatula A17 failed to allow Race 3 of H. glycines to complete its life cycle, in contrast, it provided the Race 4 population to form several cyst nematodes, however, the female index（FI） value was approximately 1.6. Three M. sativa cultivars, including Xunlu, Aergangjin and Junren, provided either Race 3 or 4 of H. glycines to develop into mature cysts with their FI value below 5 as well. Our results demonstrated that legume plants in both M. truncatula and M. sativa were not likely to be a model plant for H. glycines because of an extreme high resistance.展开更多
Rice genes OsDjA2 and OsERF104,encoding a chaperone protein and an APETELA2/ethylene-responsive factor,respectively,are strongly induced in a compatible interaction with blast fungus,and also have function in plant su...Rice genes OsDjA2 and OsERF104,encoding a chaperone protein and an APETELA2/ethylene-responsive factor,respectively,are strongly induced in a compatible interaction with blast fungus,and also have function in plant susceptibility validated through gene silencing.Here,we reported the CRISPR/Cas9 knockout of OsDjA2 and OsERF104 genes resulting in considerable improvement of blast resistance.A total of 15 OsDjA2(62.5%)and 17 OsERF104(70.8%)T_(0)transformed lines were identified from 24 regenerated plants for each target and used in downstream experiments.Phenotyping of homozygous T1 mutant lines revealed not only a significant decrease in the number of blast lesions but also a reduction in the percentage of diseased leaf area,compared with the infected control plants.Our results supported CRISPR/Cas9-mediated target mutation in rice susceptibility genes as a potential and alternative breeding strategy for building resistance to blast disease.展开更多
It has been reported in several pathosystems that disease resistance can vary in leaves at different stages. However, how general this leaf stage-associated resistance is, and the molecular mechanism（s） underly- ing...It has been reported in several pathosystems that disease resistance can vary in leaves at different stages. However, how general this leaf stage-associated resistance is, and the molecular mechanism（s） underly- ing it, remain largely unknown. Here, we investigated the effect of leaf stage on basal resistance, effector- triggered immunity （ETI） and nonhost resistance, using eight pathosystems involving the hosts Arabidopsis thaliana, Nicotiana tabacum, and N. benthamiana and the pathogens Sclerotinia sclerotiorum, Pseudomonas syringae pv. tabaci, P. syringae pv. tomato DC3000, and Xanthomonas oryzae pv. oryzae （Xoo）. We show evidence that leaf stage-associated resistance exists ubiquitously in plants, but with varying intensity at different stages in diverse pathosystems. Microarray expression profiling assays demonstrated that hundreds of genes involved indefense responses, phytohormone biosynthesis and signaling, and calcium signaling, were differentially expressed between leaves at different stages. The Arabidopsis mutants sid1, sid2-3, ein2, jar1-1, abal and aao3 lost leaf stage-associated resistance to S. sclerotiorum, and the mutants abal and sid2-3 were affected in leaf stage-associated RPS2/AvrRpt2＋-con- ferred ETI, whereas only the mutant sid2-3 influenced leaf stage-associated nonhost resistance to Xoo. Our results reveal that the phytohormones salicylic acid, ethylene, jasmonic acid and abscisic acid likely play an essential, but pathosystem-dependent, role in leaf stage- associated resistance.展开更多
基金Supported by the National Natural Science Foundation of China （30125030） and the Knowledge Innovation Program of the Chinese Academy of Sciences （KSCX2-SW-301-02）.
文摘The fungal pathogen Sclerotinia sclerotiorum Libert causes rot diseases on many crops worldwide and large economic losses occur frequently because of a lack of resistant varieties. The pathogenesis of S. sclerotiorum and the molecular basis of plant responses to the pathogen are poorly understood. In the present investigation, the process of S. sclerotiorum infection in Arabidopsis thaliana L., a plant that is highly susceptible to this fungus, was analysed. In addition, the defense activation in the host was investigated. A convenient inoculation method using millet grain was developed for S. sclerotiorum in Arabidopsis. The fungus rapidly infected the plants, probably through ball- or cushion-like infection structures. Visible symptoms developed within 24 h and plants were killed 72 h after inoculation. Cellulase, the main enzyme that caused host tissues to rot, was secreted by S. sclerotiorum in a pH-dependent manner. Oxalic acid, another pathogenic factor secreted by the fungus, induced necrotic lesions on the leaves, infection with S. sclerotiorum strongly induced the production of the pathogenesis-related （PR） proteins β-1,3-glucanase and chitinase in Arabidopsis. Furthermore, the PR gene PDF. 1 was induced, but not PR1, indicating that the pathogen activated basal defense of jasmonic acid/ethylene dependence, which is consistent with its necrotrophic characteristics. This pathosystem for Arabidopsis-S. sclerotiorum could provide an approach for the analysis of the interactions between S. sclerotiorum and other crops, thereby facilitating genetic manipulation techniques for controlling this pathogen.
基金supported by grants from the National Natural Science Foundation of China (31301645, 31171827)the National 973 Program of China (2013CB127502)
文摘Soybean cyst nematode Heterodera glycines is one of the most serious soil-borne pathogens in soybean production. However, the researches were limited in China due to lack of an effective pathosystem. In this study, we screened 21 legume Medicago plants in both Medicago truncatula and Medicago sativa to obtain candidate model plants for establishing a new pathosystem for legume-H. glycines interactions. The nematode infection of tested plants was assayed with Race 3 and 4 respectively, which were two dominant H. glycines inbred races in China soybean producing areas. The results showed that the model legume plant M. truncatula A17 failed to allow Race 3 of H. glycines to complete its life cycle, in contrast, it provided the Race 4 population to form several cyst nematodes, however, the female index（FI） value was approximately 1.6. Three M. sativa cultivars, including Xunlu, Aergangjin and Junren, provided either Race 3 or 4 of H. glycines to develop into mature cysts with their FI value below 5 as well. Our results demonstrated that legume plants in both M. truncatula and M. sativa were not likely to be a model plant for H. glycines because of an extreme high resistance.
基金financially supported by Brazilian Agricultural Research Corporation (Embrapa)-Coordination for the Improvement of Higher Education PersonnelNational Council for Scientific and Technological Development, Federal District Research Support FoundationFoundation for Scientific and Technological Development of Mato Grosso do Sul State
文摘Rice genes OsDjA2 and OsERF104,encoding a chaperone protein and an APETELA2/ethylene-responsive factor,respectively,are strongly induced in a compatible interaction with blast fungus,and also have function in plant susceptibility validated through gene silencing.Here,we reported the CRISPR/Cas9 knockout of OsDjA2 and OsERF104 genes resulting in considerable improvement of blast resistance.A total of 15 OsDjA2(62.5%)and 17 OsERF104(70.8%)T_(0)transformed lines were identified from 24 regenerated plants for each target and used in downstream experiments.Phenotyping of homozygous T1 mutant lines revealed not only a significant decrease in the number of blast lesions but also a reduction in the percentage of diseased leaf area,compared with the infected control plants.Our results supported CRISPR/Cas9-mediated target mutation in rice susceptibility genes as a potential and alternative breeding strategy for building resistance to blast disease.
基金supported by grants from the National Natural Science Foundation of China (31672014 and 31371892)the Zhejiang Provincial Natural Science Foundation of China (LZ18C140002)+1 种基金the Genetically Modified Organisms Breeding Major Projects (2014ZX0800905B)the Fundamental Research Funds for the Central Universities
文摘It has been reported in several pathosystems that disease resistance can vary in leaves at different stages. However, how general this leaf stage-associated resistance is, and the molecular mechanism（s） underly- ing it, remain largely unknown. Here, we investigated the effect of leaf stage on basal resistance, effector- triggered immunity （ETI） and nonhost resistance, using eight pathosystems involving the hosts Arabidopsis thaliana, Nicotiana tabacum, and N. benthamiana and the pathogens Sclerotinia sclerotiorum, Pseudomonas syringae pv. tabaci, P. syringae pv. tomato DC3000, and Xanthomonas oryzae pv. oryzae （Xoo）. We show evidence that leaf stage-associated resistance exists ubiquitously in plants, but with varying intensity at different stages in diverse pathosystems. Microarray expression profiling assays demonstrated that hundreds of genes involved indefense responses, phytohormone biosynthesis and signaling, and calcium signaling, were differentially expressed between leaves at different stages. The Arabidopsis mutants sid1, sid2-3, ein2, jar1-1, abal and aao3 lost leaf stage-associated resistance to S. sclerotiorum, and the mutants abal and sid2-3 were affected in leaf stage-associated RPS2/AvrRpt2＋-con- ferred ETI, whereas only the mutant sid2-3 influenced leaf stage-associated nonhost resistance to Xoo. Our results reveal that the phytohormones salicylic acid, ethylene, jasmonic acid and abscisic acid likely play an essential, but pathosystem-dependent, role in leaf stage- associated resistance.
