Rice sheath blight, caused by Rhizoctonia solani AG1-IA, is a major disease in rice-growing areas worldwide. Effectors of phytopathogenic fungi play important roles during the infection process of fungal pathogens ont...Rice sheath blight, caused by Rhizoctonia solani AG1-IA, is a major disease in rice-growing areas worldwide. Effectors of phytopathogenic fungi play important roles during the infection process of fungal pathogens onto their host plants. However, the molecular mechanisms by which R. solani effectors regulate rice immunity are not well understood. Through prediction, 78 candidate effector molecules were identified. Using the tobacco rattle virus-host induced gene silencing(TRV-HIGS) system, 45 RNAi constructs of effector genes were infiltrated into Nicotiana benthamiana leaves. The results revealed that eight of these constructs resulted in a significant reduction in necrosis caused by infection with the AG1-IA strain GD-118. Additionally, stable rice transformants carrying the double-stranded RNA construct for one of the effector genes, AGLIP1, were generated to further verify the function of this gene. The suppression of the AGLIP1 gene increased the resistance of both N. benthamiana and rice against GD-118, and also affected the growth rate of GD-118, indicating that AGLIP1 is a key pathogenic factor. Small RNA sequencing showed that the HIGS vectors were processed into si RNAs within the plants and then translocated to the fungi, leading to the silencing of the target genes. As a result, AGLIP1 might be an excellent candidate for HIGS, thereby enhancing crop resistance against the pathogen and contributing to the control of R. solani infection.展开更多
【目的】明确中国南方水稻纹枯病菌不同地理群体的遗传结构,为研究该病害的流行规律提供信息。【方法】采用8个SSR荧光标记对收集自中国南方8省(自治区)的188个水稻纹枯病菌进行检测。利用POPGENE version 1.31软件计算各项遗传多样性参...【目的】明确中国南方水稻纹枯病菌不同地理群体的遗传结构,为研究该病害的流行规律提供信息。【方法】采用8个SSR荧光标记对收集自中国南方8省(自治区)的188个水稻纹枯病菌进行检测。利用POPGENE version 1.31软件计算各项遗传多样性参数,近交系数由FSTAT 2.9.3软件估算。基于马尔可夫链模型,采用GENEPOP 4.2软件以卡方检验估计Hardy-Weinberg平衡。应用Arlequin 3.1软件进行分子方差变异分析,并通过遗传分化系数计算基因流。基于Nei’s遗传距离,利用MEGA5.0软件构建UPGMA树状图。使用STRUCTURE 2.3.3软件的贝叶斯聚类法进行群体遗传结构分析,并估计群体间遗传混杂程度。采用Mantel test检测遗传距离与地理距离的相关性。【结果】8个地理群体的平均观测等位基因数和有效等位基因数分别为4.025和2.071。Shannon’s信息指数为0.659—1.088,平均为0.859。等位基因丰富度为2.500—5.152,平均为3.858。观测杂合度为0.425—0.619,平均为0.506。期望杂合度为0.399—0.546,平均为0.472。总群体水平的近交系数(FIS=-0.069)为负值,表明总群体内杂合子过剩(纯合子缺失)。Hardy-Weinberg平衡检验表明,在6个群体中存在因杂合子的缺失或过剩引起的平衡偏离,暗示了水稻纹枯病菌同时具有克隆生长和有性繁殖,两种繁殖方式间的平衡因群体而异。AMOVA分析结果显示,有88.14%的遗传变异来自群体内部的个体间,表明遗传变异主要发生在群体内。Mantel检测发现,遗传距离与其地理距离之间呈显著正相关(r=0.422,P=0.025)。UPGMA聚类表明,所有群体可被划分为遗传分化明显的两个亚群(FST=0.209—0.624),其中位于珠江沿岸的广宁和长塘群体为一个组群,而位于长江沿岸的6个群体为另一组群,与遗传结构分析结果一致。位于长江沿岸的群体遗传混杂明显,基因交流水平高(Nm=2.525—8.447),群体分化程度较低(FST=0.029—0.094)。【结论】中国南方水稻纹枯病菌分布范围广泛、可能的混合繁殖模式以及菌核或菌丝具有远距离传播特性,是导致其遗传多样性水平较高的原因。长江亚群内部个体在不同群体之间的迁移所形成的基因流动,在一定程度上阻止了群体间的遗传分化。而长江亚群和珠江亚群之间存在明显的遗传分化,推测病原菌有限的长距离迁移可能是群体遗传变异空间结构形成的主要原因。展开更多
【目的】旨在获得对水稻纹枯病有生防效果的拮抗细菌,探索生防细菌作用机理。【方法】通过苗期防病试验从本实验室保存的7株拮抗细菌中筛选对水稻纹枯病有较好防病效果的菌株。结合生理生化性状和16S r DNA基因序列同源性分析,对生防细...【目的】旨在获得对水稻纹枯病有生防效果的拮抗细菌,探索生防细菌作用机理。【方法】通过苗期防病试验从本实验室保存的7株拮抗细菌中筛选对水稻纹枯病有较好防病效果的菌株。结合生理生化性状和16S r DNA基因序列同源性分析,对生防细菌7-5进行初步鉴定,并通过PCR扩增、薄层层析等探讨7-5产生抗生素的种类。【结果】供试7株细菌中7-5、4-74和4-78对水稻纹枯病防效分别可达69.0%、70.8%和75.4%。其中4-74和4-78抑菌谱窄,7-5对水稻纹枯病菌、桃褐腐病菌和草莓灰霉病菌都具有较强抑菌能力。菌株7-5鉴定为绿针假单胞菌;该菌株可产生吩嗪-1-羧酸、嗜铁素、氢氰酸、蛋白酶、藤黄绿脓菌素和2,4-二乙酰基间苯三酚等抗菌物质,不产生硝吡咯菌素、几丁质酶和纤维素酶。【结论】绿针假单胞菌7-5主要通过产生抗生素防治水稻纹枯病。展开更多
基金supported by the Henan Province Science and Technology Research Project, China (Grant No. 242102110232)the National Natural Science Foundation of China (Grant No. 31801677)the Major Program of Guangdong Basic and Applied Basic Research, China (Grant No. 2019B030302006)。
文摘Rice sheath blight, caused by Rhizoctonia solani AG1-IA, is a major disease in rice-growing areas worldwide. Effectors of phytopathogenic fungi play important roles during the infection process of fungal pathogens onto their host plants. However, the molecular mechanisms by which R. solani effectors regulate rice immunity are not well understood. Through prediction, 78 candidate effector molecules were identified. Using the tobacco rattle virus-host induced gene silencing(TRV-HIGS) system, 45 RNAi constructs of effector genes were infiltrated into Nicotiana benthamiana leaves. The results revealed that eight of these constructs resulted in a significant reduction in necrosis caused by infection with the AG1-IA strain GD-118. Additionally, stable rice transformants carrying the double-stranded RNA construct for one of the effector genes, AGLIP1, were generated to further verify the function of this gene. The suppression of the AGLIP1 gene increased the resistance of both N. benthamiana and rice against GD-118, and also affected the growth rate of GD-118, indicating that AGLIP1 is a key pathogenic factor. Small RNA sequencing showed that the HIGS vectors were processed into si RNAs within the plants and then translocated to the fungi, leading to the silencing of the target genes. As a result, AGLIP1 might be an excellent candidate for HIGS, thereby enhancing crop resistance against the pathogen and contributing to the control of R. solani infection.
文摘【目的】旨在获得对水稻纹枯病有生防效果的拮抗细菌,探索生防细菌作用机理。【方法】通过苗期防病试验从本实验室保存的7株拮抗细菌中筛选对水稻纹枯病有较好防病效果的菌株。结合生理生化性状和16S r DNA基因序列同源性分析,对生防细菌7-5进行初步鉴定,并通过PCR扩增、薄层层析等探讨7-5产生抗生素的种类。【结果】供试7株细菌中7-5、4-74和4-78对水稻纹枯病防效分别可达69.0%、70.8%和75.4%。其中4-74和4-78抑菌谱窄,7-5对水稻纹枯病菌、桃褐腐病菌和草莓灰霉病菌都具有较强抑菌能力。菌株7-5鉴定为绿针假单胞菌;该菌株可产生吩嗪-1-羧酸、嗜铁素、氢氰酸、蛋白酶、藤黄绿脓菌素和2,4-二乙酰基间苯三酚等抗菌物质,不产生硝吡咯菌素、几丁质酶和纤维素酶。【结论】绿针假单胞菌7-5主要通过产生抗生素防治水稻纹枯病。
