水稻稻瘟病抗性基因的克隆、育种利用及稻瘟菌无毒基因研究进展

稻瘟病是世界上影响水稻(Oryza sativa)粮食生产的主要病害之一, 抗病基因的发掘与利用是抗病育种的基础和核心。随着寄主水稻和病原菌稻瘟病菌(Magnaporthe oryzae)基因组测序和基因注释的完成, 水稻和稻瘟病菌的互作体系成为研究植物与真菌互作的模式系统。该文对稻瘟病抗病基因的遗传、定位、克隆及育种利用进行概述, 并通过生物信息学分析方法, 探讨了水稻全基因组中NBS-LRR类抗病基因在水稻12条染色体上的分布情况, 同时对稻瘟病菌无毒基因的鉴定及无毒蛋白与抗病蛋白的互作进行初步分析。最后对稻瘟病抗病基因研究存在的问题进行分析并展望了未来的研究方向, 以期为水稻抗稻瘟病育种发展和抗病机制的深入理解提供参考。     

抗稻瘟病水稻资源抗性基因Pita、Pib、Pi9以及Pikm的分布研究

利用抗稻瘟病水稻资源品种杂交,聚合多个抗性基因是培育持久抗稻瘟病水稻新品种的主要育种途径.利用分子标记技术对水稻抗性资源进行基因型鉴定是分子辅助聚合育种的基础.通过以亚华种业科学院稻瘟病病圃抗病水稻资源为材料,利用特异性分子标记对Pi9、Pita、Pib以及Pikm基因在水稻抗稻瘟病资源的分布进行了鉴定,初步建立了抗性基因数据库.同时对抗性基因及与抗性反应的相关性进行了探讨,结果表明以Pi9为主效基因,同时聚合Pita和Pib抗性基因能提高持久抗稻瘟病能力.     

转基因改良水稻抗稻瘟病的策略及其进展

稻瘟病是由子囊菌引起的广泛发生在世界各水稻产区的主要真菌病害。由于病原菌致病性的高度分化,使得对稻瘟病很难控制和防治。长期实践证明,培育抗病品种是稻瘟病抗病育种的主要目标。随着基因工程的发展,利用转基因技术导入外源基因改良稻瘟病抗性已成为一条新途径。现有研究表明,通过某些抗病基因、抗真菌蛋白基因、杀菌肽基因的克隆和转育,可以培育出获得对稻瘟病广谱抗性的水稻品种(系)。     

水稻抗稻瘟病近等基因系的cDNA微阵列分析

应用cDNA微阵列对来源于中156／谷梅2号重组自交系的水稻抗稻瘟病近等基因系G205和G71的稻瘟病菌胁迫基因表达谱进行了分析,发现有3个cDNA克隆的表达仅在抗病基因系G205接种病原菌12h后受到诱导,其中两个为功能已知基因,另一个为功能未知的新基因。另有35个差异表达克隆在两个近等基因系中均检测到,其中17个克隆的表达在G205和G71均受到病原菌的诱导,另外18个克隆的表达则在G205和G71均受到病原菌原抑制。序列分析表明,这些稻瘟病菌应答基因分别与防卫反应,信号传递,逆境胁迫和光合作用及糖代谢等功能相关,为植物抗病机制提供了相关信息。另外,Northern还证实了编码富含甘氨酸蛋白基因（Glycinerich protein Grp)的表达受稻瘟病病原菌的诱导,是一个稻瘟病诱导相关基因。     

水稻抗稻瘟病基因的标记辅助选择及定位克隆

水稻抗稻瘟病基因-稻瘟病菌无毒基因相互作用体系是当今植物分子病理学和抗病育种学研究领域的模式体系之一,其中抗病基因的分子定位与克隆及其标记辅助选择已成为该体系的重要内容。本文就这方面的研究进展作一简要综述,以期为水稻抗病育种提供有益的信息。     

植物抗病分子机制研究进展

近十年来,植物抗病分子机制研究取得显著进展。综述了植物抗病基因的克隆及其结构分析、病原菌无毒基因及其相关致病因子的克隆与研究、信号传导相关因子的克隆及其结构分析以及植物-病原菌的相互作用研究,重点介绍了以植物特异抗病基因为介导的诱导防卫作用机制(包括抗病基因编码毒素蛋白,进而抑制病原菌的繁殖;显性基因编码病原菌致病性的靶标物;抗病基因表达产物直接引发抗病反应和基因对基因的抗病作用机制等)的研究进展,以期为植物抗病育种提供有益的信息。     

植物抗病分子机制研究进展

近十年来,植物抗病分子机制研究取得显著进展.综述了植物抗病基因的克隆及其结构分析、病原菌无毒基因及其相关致病因子的克隆与研究、信号传导相关因子的克隆及其结构分析以及植物-病原菌的相互作用研究,重点介绍了以植物特异抗病基因为介导的诱导防卫作用机制(包括抗病基因编码毒素蛋白,进而抑制病原菌的繁殖;显性基因编码病原菌致病性的靶标物;抗病基因表达产物直接引发抗病反应和基因对基因的抗病作用机制等)的研究进展,以期为植物抗病育种提供有益的信息.     

水稻广谱抗稻瘟病基因研究进展

稻瘟病是水稻生产中的最严重病害之一,由于稻瘟菌小种的高度变异性,垂直抗性基因难以持续控制稻瘟病的危害,因此,克隆和利用广谱持久抗瘟基因被认为是解决稻瘟病问题最经济有效的策略。本文从广谱抗源的筛选与利用,广谱抗瘟基因的定位、克隆与应用等方面对水稻广谱抗稻瘟病基因研究取得的进展进行了概述,并介绍了广谱抗性分子机理的最新研究进展。基于国内外稻瘟病抗性基因研究的现状及趋势,以及我国丰富的抗瘟水稻种质资源,克隆越来越多的广谱抗瘟基因具有重要的理论与应用价值。     

水稻稻瘟病和纹枯病抗性鉴定方法

水稻(Oryza sativa)是世界上最重要的粮食作物, 但稻瘟病和纹枯病等病害严重危害水稻的产量和品质, 给我国乃至全球粮食安全带来巨大威胁。鉴定水稻抗病资源、克隆抗病基因、揭示抗性机理并在育种中加以利用, 对抵御水稻病害和保障粮食安全具有十分重要的作用。准确评价水稻资源的抗病性, 是开展抗病机理研究和育种生产应用的关键环节。该文详述了水稻幼苗期人工喷雾接种、分蘖期和孕穗期田间注射接种与离体叶片戳伤接种的稻瘟病抗性鉴定方法, 以及水稻分蘖期田间接种、孕穗期温室接种和离体茎秆接种的纹枯病抗性鉴定方法, 以期为同行鉴定水稻资源、开展抗病理论和应用研究提供参考。     

水稻抗稻瘟病天然免疫机制及抗病育种新策略

稻瘟病是水稻最严重的病害之一,由子囊菌(Magnaporthe oryzae)引起。利用抗病品种是防治稻瘟病最经济、最有效的措施。近年来,稻瘟病已发展为研究植物与病原真菌分子互作机制的模式系统,在水稻与稻瘟菌互作和寄主抗性分子生物学、基因组学和蛋白组学等领域取得了一系列重要的研究成果。文章综述了近年来水稻抗稻瘟病两种天然免疫机制,即病原菌相关分子模式诱导和效应蛋白诱导的抗病机制研究的最新进展,讨论了GWAS、TALLEN、CRISPR和HIGS等基因组研究新方法和新技术在水稻抗病育种中的应用,并对目前稻瘟病抗性机制研究和抗病育种中的问题和挑战进行了探讨和展望。     

Blast resistance in rice: a review of conventional breeding to molecular approaches

Blast disease caused by the fungal pathogen Magnaporthe oryzae is the most severe diseases of rice. Using classical plant breeding techniques, breeders have developed a number of blast resistant cultivars adapted to different rice growing regions worldwide. However, the rice industry remains threatened by blast disease due to the instability of blast fungus. Recent advances in rice genomics provide additional tools for plant breeders to improve rice production systems that would be environmentally friendly. This article outlines the application of conventional breeding, tissue culture and DNA-based markers that are used for accelerating the development of blast resistant rice cultivars. The best way for controlling the disease is to incorporate both qualitative and quantitative genes in resistant variety. Through conventional and molecular breeding many blast-resistant varieties have been developed. Conventional breeding for disease resistance is tedious, time consuming and mostly dependent on environment as compare to molecular breeding particularly marker assisted selection, which is easier, highly efficient and precise. For effective management of blast disease, breeding work should be focused on utilizing the broad spectrum of resistance genes and pyramiding genes and quantitative trait loci. Marker assisted selection provides potential solution to some of the problems that conventional breeding cannot resolve. In recent years, blast resistant genes have introgressed into Luhui 17, G46B, Zhenshan 97B, Jin 23B, CO39, IR50, Pusa1602 and Pusa1603 lines through marker assisted selection. Introduction of exotic genes for resistance induced the occurrence of new races of blast fungus, therefore breeding work should be concentrated in local resistance genes. This review focuses on the conventional breeding to the latest molecular progress in blast disease resistance in rice. This update information will be helpful guidance for rice breeders to develop durable blast resistant rice variety through marker assisted selection.     

Characterizing rice lesion mimic mutants and identifying a mutant with broad-spectrum resistance to rice blast and bacterial blight

Many plant mutants develop spontaneous lesions that resemble disease symptoms in the absence of pathogen attack. In several pathosystems, lesion mimic mutations have been shown to be involved in programmed cell death, which in some instances leads to enhanced disease resistance to multiple pathogens. We investigated the relationship between spontaneous cell death and disease resistance in rice with nine mutants with a range of lesion mimic phenotypes. All nine mutations are controlled by recessive genes and some of these mutants have stunted growth and other abnormal characteristics. The lesion mimics that appeared on the leaves of these mutants were caused by cell death as measured by trypan blue staining. Activation of six defense-related genes was observed in most of the mutants when the mimic lesions developed. Four mutants exhibited significant enhanced resistance to rice blast. One of the mutants, spl11, confers non-race-specific resistance not only to blast but also to bacterial blight. The level of resistance in the spl11 mutant to the two pathogens correlates with the defense-related gene expression and lesion development on the leaves. The results suggest that some lesion mimic mutations in rice may be involved in disease resistance, and cloning of these genes may provide a clue to developing broad-spectrum resistance to diverse pathogens.     

Preformed expression of defense is a hallmark of partial resistance to rice blast fungal pathogen <Emphasis Type="Italic">Magnaporthe oryzae</Emphasis>

Background  

Partial resistance to plant pathogens is extensively used in breeding programs since it could contribute to resistance durability. Partial resistance often builds up during plant development and confers quantitative and usually broad-spectrum resistance. However, very little is known on the mechanisms underlying partial resistance. Partial resistance is often explained by poorly effective induction of plant defense systems. By exploring rice natural diversity, we asked whether expression of defense systems before infection could explain partial resistance towards the major fungal pathogen Magnaporthe oryzae. The constitutive expression of 21 defense-related genes belonging to the defense system was monitored in 23 randomly sampled rice cultivars for which partial resistance was measured.     

Enhanced resistance to blast fungus and bacterial blight in transgenic rice constitutively expressing OsSBP, a rice homologue of mammalian selenium-binding proteins

The rice Oryza sativa selenium-binding protein homologue (OsSBP) gene encodes a homologue of mammalian selenium-binding proteins, and it has been isolated as one of the genes induced by treating a plant with a cerebroside elicitor from rice blast fungus. The possible role of OsSBP in plant defense was evaluated by using a transgenic approach. Plants overexpressing OsSBP showed enhanced resistance to a virulent strain of rice blast fungus as well as to rice bacterial blight. The expression of defense-related genes and the accumulation of phytoalexin after infection by rice blast fungus were accelerated in the OsSBP overexpressors. A higher level of H(2)O(2) accumulation and reduced activity of such scavenging enzymes as ascorbate peroxidase and catalase were seen when the OsSBP-overexpressing plants were treated with the protein phosphatase 1 inhibitor, calyculin A. These results suggest that the upregulation of OsSBP expression conferred enhanced tolerance to different pathogens, possibly by increasing plant sensitivity to endogenous defense responses. Additionally, the OsSBP protein might have a role in modulating the defense mechanism to biotic stress in rice.     

Molecular progress on the mapping and cloning of functional genes for blast disease in rice (Oryza sativa L.): current status and future considerations

Rice blast disease, which is caused by the fungal pathogen Magnaporthe oryzae, is a recurring problem in all rice-growing regions of the world. The use of resistance (R) genes in rice improvement breeding programmes has been considered to be one of the best options for crop protection and blast management. Alternatively, quantitative resistance conferred by quantitative trait loci (QTLs) is also a valuable resource for the improvement of rice disease resistance. In the past, intensive efforts have been made to identify major R-genes as well as QTLs for blast disease using molecular techniques. A review of bibliographic references shows over 100 blast resistance genes and a larger number of QTLs (～500) that were mapped to the rice genome. Of the blast resistance genes, identified in different genotypes of rice, ～22 have been cloned and characterized at the molecular level. In this review, we have summarized the reported rice blast resistance genes and QTLs for utilization in future molecular breeding programmes to introgress high-degree resistance or to pyramid R-genes in commercial cultivars that are susceptible to M. oryzae. The goal of this review is to provide an overview of the significant studies in order to update our understanding of the molecular progress on rice and M. oryzae. This information will assist rice breeders to improve the resistance to rice blast using marker-assisted selection which continues to be a priority for rice-breeding programmes.     

Recent Advances in Cloning and Characterization of Disease Resistance Genes in Rice

Rice diseases caused by fungi, bacteria and viruses are one of the major constraints for sustainable rice （Oryza sativa L.） production worldwide. The use of resistant cultivars is considered the most economical and effective method to control rice diseases. In the last decade, a dozen resistance genes against the fungal pathogen Magnaporthe grisea and the bacterial pathogen Xanthomonas oryzae pv. oryzae have been cloned. Approximately half of them encode nuclear binding site （NBS） and leucine rich repeat （LRR）-containing proteins, the most common type of cloned plant resistance genes. Interestingly, four of them encode novel proteins which have not been identified in other plant species, suggesting that unique mechanisms might be involved in rice defense responses. This review summarizes the recent advances in cloning and characterization of disease resistance genes in rice and presents future perspectives for in-depth molecular analysis of the function and evolution of rice resistance genes and their interaction with avirulence genes in pathogens.     

Overexpression of a rice defense-related F-box protein gene OsDRF1 in tobacco improves disease resistance through potentiation of defense gene expression

F-box proteins play important roles in plant growth/development and responses to environmental stimuli through targeting substrates into degradation machinery. A rice defense-related F-box protein gene, OsDRF1, was cloned and identified during a course of study aimed at elucidating the molecular basis of induced immunity in rice. OsDRF1 encodes a protein of 328 amino acids, containing a highly conserved F-box domain. Expression of OsDRF1 was induced upon treatment with benzothiadiazole (BTH), a chemical inducer of defense responses in rice. Moreover, in BTH-treated rice seedlings, expression of OsDRF1 was further induced by infection with Magnaporthe grisea, the rice blast fungus, compared with those in water-treated seedlings. OsDRF1 was also upregulated in rice seedlings after treatment with ABA. Overexpression of OsDRF1 in transgenic tobacco resulted in enhanced disease resistance against tomato mosaic virus (ToMV) and Pseudomonas syringae pv. tabaci and strengthened expression of defense-related genes after salicylic acid treatment or ToMV infection. Root elongation of the OsDRF1-overexpressing transgenic seedlings was significantly inhibited by ABA, indicating that overexpression of OsDRF1 resulted in increased ABA sensitivity. The results suggest that OsDRF1 plays a role in disease resistance via upregulating defense-related gene expression and that OsDRF1 may also be involved in the response to ABA.