国外引进水稻种质资源的稻瘟病抗性基因检测与评价

为了筛选出福建省水稻稻瘟病重发区育种中可利用的新抗性资源,在福建省上杭县对156份外引水稻种质资源进行了2年田间自然诱发鉴定,并对Pi2、Pi9、Pi5、Pi54、Pikm、Pita、Pia和Pib等8个稻瘟病抗性基因做了分子检测。结果表明:156份资源对苗瘟、叶瘟、穗颈瘟和综合抗性表现抗病的分别有10份、14份、29份和26份,且苗瘟抗性级别与叶瘟抗性级别(r=0.816,P<0.01)、苗瘟抗性级别与穗颈瘟抗性级别(r=0.347,P<0.01)、以及叶瘟抗性级别与穗颈瘟抗性级别(r=0.344,P<0.01),均呈极显著正相关。分子标记检测到携带稻瘟病抗性基因Pi9、Pi2、Pi54、Pikm、Pi5、Pib、Pia和Pita的水稻资源分别有1、6、20、22、37、88、101和106份,其中携带稻瘟病抗性基因Pi9和Pi2的水稻资源的抗性表现较好,表现抗病的超过60%,携带其他稻瘟病抗性基因的水稻资源表现抗病的均在50%以下;水稻资源携带0~6个稻瘟病抗性基因,随着携带抗性基因数目增加,抗病率呈上升趋势,综合抗性等级呈下降趋势。进一步研究发现,携带Pi9+Pi5+Pikm+Pia、Pi5+Pib+Pita+Pikm+Pia和Pi2+Pi54+Pib+Pita+Pikm+Pia等3个基因型的水稻资源,稻瘟病抗性较好。最后,筛选了8份稻瘟病抗性较好的材料,提供育种者参考、利用。     

云南疣粒野生稻稻瘟病抗性

野生稻(Oryza rufipogo)保存有许多栽培稻(O. sativa)不具备或已经消失的优异基因资源, 是扩大栽培稻遗传背景、改良产量与品质、提高抗病虫害及抗逆境能力的重要基因库。疣粒野生稻(O. meyeriana)是中国3种野生稻资源之一, 主要分布在云南。为进一步了解其稻瘟病抗性, 首先利用来自不同稻作区的稻瘟病菌株, 通过注射接种法对疣粒野生稻进行系统的稻瘟病抗性鉴定, 发现疣粒野生稻对接种的所有稻瘟病菌株都感病。进一步采用3'/5' RACE方法, 从疣粒野生稻中克隆了水稻同源基因Pid2和Pid3, 并构建过表达转基因株系对基因功能进行了研究。结果表明, Pid2和Pid3与疣粒野生稻中同源基因间在DNA和氨基酸水平上有较大的序列差异, 过表达转基因的日本晴植株对稻瘟病菌的敏感性与对照相似。推测疣粒野生稻在自然接种条件下, 表现出的抗稻瘟病表型很可能是其旱生叶片结构特征形成了对稻瘟病菌侵染的天然屏障。对控制疣粒野生稻这一类性状基因资源的挖掘和利用, 有利于优良抗性水稻品种的培育。研究结果为疣粒野生稻的研究利用提供了新信息和新思路。     

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.     

Genetic Analysis of Resistance to Rice Blast: A Study on the Inheritance of Resistance to the Blast Disease Pathogen in an F3 Population of Rice

Blast caused by the fungus Magnaporthae grisea (Herbert) Borr. (anamorphe Pyricularia oryza Cav.) is a serious disease of rice (Oryza sativa L.). One method to overcome this disease is to develop disease resistant cultivars. Due to the genetic plasticity in the pathogen genome, there is a continuous threat to the effectiveness of the developed cultivars. Additional studies of the genetics of resistance, virulence stability and functional genomics are required to accelerate research into understanding the molecular basis of blast disease resistance. In this study, individual plants of the F₃ population derived from Pongsu Seribu 2 and Mahsuri were used for pathogenesis assays and inheritance studies of blast resistance. The study was performed with two of the most virulent Malaysian M. grisea pathotypes: P7.2 and P5.0. For blast screening, plants were scored based on the IRRI Standard Evaluation System (SES). F₃ populations showed a segregation ratio of 3R:1S for pathotype P7.2, indicating that resistance to this pathotype is likely controlled by a single nuclear gene. Chi‐square analysis showed that the F₃ families segregated in a 15R:1S ratio for pathotype P5.0. Therefore, locus interactions or epitasis of blast resistance occur against pathotype P5.0 in the F₃ population derived from Pongsu Seribu 2 and Mahsuri. This can be explained by the presence of two independent dominant genes that when present simultaneously, provide resistance to the M. gresia pathotype P5.0. These results indicated that blast resistance in rice is due to the combined effects of multiple loci with major and minor effects. The genetic data generated here will be useful in the breeding of local cultivars for resistance to field blast. The methodology reported here will facilitate the mapping of genes and quantitative trait loci (QTLs) underlying the blast resistance trait.     

Conventional Breeding and Molecular Markers for Blast Disease Resistance in Rice (<i>Oryza sativa</i> L.)

Monogenic lines, which carried 23 genes for blast resistance were tested and used donors to transfer resistance genes by crossing method. The results under blast nursery revealed that 9 genes from 23 genes were susceptible to highly susceptible under the three locations (Sakha, Gemmeza, and Zarzoura in Egypt); Pia, Pik, Pik-p, Piz-t, Pita, Pi b, Pi, Pi 19 and Pi 20. While, the genes Pii, Pik-s, Pik-h, Pi z, Piz-5, Pi sh, Pi 3, Pi 1, Pi 5, Pi 7, Pi 9, Pi 12, Pikm and Pita-2 were highly resistant at the same locations. Clustering analysis confirmed the results, which divided into two groups; the first one included all the susceptible genes, while the second one included the resistance genes. In the greenhouse test, the reaction pattern of five races produced 100% resistance under artificial inoculation with eight genes showing complete resistance to all isolates. The completely resistant genes: Pii, Pik-s, Piz, Piz-5 (=bi2) (t), Pita (=Pi4) (t), Pita, Pi b and Pi1 as well as clustering analysis confirmed the results. In the F₁ crosses, the results showed all the 25 crosses were resistant for leaf blast disease under field conditions. While, the results in F₂ population showed seven crosses with segregation ratio of 15 (R):1 (S), two cross gave segregated ratio of 3 R:1 S and one gave 13:3. For the identi- fication of blast resistance genes in the parental lines, the marker K3959, linked to Pik-s gene and the variety IRBLKS-F5 carry this gene, which was from the monogenic line. The results showed that four genotypes; Sakha 105, Sakha 103, Sakha 106 and IRBLKS-F5 were carrying Pik-s gene, while was absent in the Sakha 101, Sakha 104, IRBL5-M, IRBL9-W, IRBLTACP1 and IRBL9-W(R) genotypes. As for Pi 5 gene, the results showed that it was present in Sakha 103 and Sakha 104 varieties and absent in the rest of the genotypes. In addition, Pita-Pita- 2 gene was found in the three Egyptian genotypes (Sakha 105, Sakha 101 and Sakha 104) plus IRBLTACP1 monogenetic. In F2 generation, six populations were used to study the inheritance of blast resistance and specific primers to confirm the ratio and identify the resistance genes. However, the ratios in molecular markers were the same of the ratio under field evaluation in the most population studies. These findings would facilitate in breeding programs for gene pyramiding and gene accumulation to produce durable resistance for blast using those genotypes.     

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.     

Identification of Two Blast Resistance Genes in a Rice Variety, Digu

Blast, caused by Magnaporthe grisea is one of most serious diseases of rice worldwide. A Chinese local rice variety, Digu, with durable blast resistance, is one of the important resources for rice breeding for resistance to blast (M. grisea) in China. The objectives of the current study were to assess the identity of the resistance genes in Digu and to determine the chromosomal location by molecular marker tagging. Two susceptible varieties to blast, Lijiangxintuanheigu (LTH) and Jiangnanxiangnuo (JNXN), a number of different varieties, each containing one blast resistance gene, Pik^s, Pia, Pik, Pi‐b, Pi‐k^p, Pi‐ta², Pi‐ta, Pi‐z, Pi‐i, Pi‐k^m, Pi‐z^t, Pi‐t and Pi‐11, and the progeny populations from the crosses between Digu and each of these varieties were analysed with Chinese blast isolates. We found that the resistance of Digu to each of the two Chinese blast isolates, ZB13 and ZB15, were controlled by two single dominant genes, separately. The two genes are different from the known blast resistance genes and, therefore, designated as Pi‐d(t)1 and Pi‐d(t)2. By using bulked segregation method and molecular marker analysis in corresponding F₂ populations, Pi‐d(t)1 was located on chromosome 2 with a distance of 1.2 and 10.6 cM to restriction fragment length polymorphism (RFLP) markers G1314A and G45, respectively. And Pi‐d(t)2 was located on chromosome 6 with a distance of 3.2 and 3.4 cM to simple sequence repeat markers RM527 and RM3, respectively. We also developed a novel strategy of resistance gene analogue (RGA) assay with uneven polymerase chain reaction (PCR) to further tag the two genes and successfully identified two RGA markers, SPO01 and SPO03, which were co‐segregated toPi‐d(t)1 and Pi‐d(t)2, respectively, in their corresponding F₂ populations. These results provide essential information for further utilization of the Digu's blast resistance genes in rice disease resistance breeding and positional cloning of these genes.     

Introgression of Pi2 and Pi5 Genes for Blast (Magnaporthe oryzae) Resistance in Rice and Field Evaluation of Introgression Lines for Resistance and Yield Traits

Blast caused by Magnaporthe oryzae is the most devastating disease causing significant loss in rice production. The destructive nature of the disease is mainly due to the genetic plasticity of M. oryzae which complicates the breeding strategies. Blast can be effectively managed by the deployment of R genes. In this study, broad‐spectrum blast resistance genes Pi2 and Pi5 were introgressed independently into popular but blast susceptible rice variety, Samba Mahsuri (BPT5204) by applying marker‐assisted backcross breeding approach. Tightly linked markers AP5930 for Pi2 and 40N23r for Pi5 gene were used in foreground selection. Background selection helped to identify the lines with maximum recovery of recurrent parent genome (RPG). The RPG recovery in Pi2 introgression lines was up to 90.17 and 91.46% in Pi5 lines. Homozygous introgression lines in BC₃F₄ generation carrying Pi2 and Pi5 gene were field evaluated for blast resistance, yield per se and yield‐related traits. The lines showed resistance to leaf and neck blast in multilocation field evaluation. Improved BPT5204 lines with improvement for blast resistance were on par with original BPT5204 in terms of grain yield and grain features.     

A Rapid and Simple Method for DNA Preparation of Magnaporthe oryzae from Single Rice Blast Lesions for PCR-Based Molecular Analysis

Rice blast is one of the most destructive diseases of rice worldwide, and the causative agent is the filamentous ascomycete Magnaporthe oryzae. With the successful cloning of more and more avirulence genes from M. oryzae, the direct extraction of M. oryzae genomic DNA from infected rice tissue would be useful alternative for rapid monitoring of changes of avirulence genes without isolation and cultivation of the pathogen. In this study, a fast, low-cost and reliable method for DNA preparation of M. oryzae from a small piece of infected single rice leaf or neck lesion was established. This single step method only required 10 min for DNA preparation and conventional chemical reagents commonly found in the laboratory. The AvrPik and AvrPi9 genes were successfully amplified with the prepared DNA. The expected DNA fragments from 570 bp to 1,139 bp could be amplified even three months after DNA preparation. This method was also suitable for DNA preparation from M. oryzae strains stored on the filter paper. All together these results indicate that the DNA preparation method established in this study is reliable, and could meet the basic needs for polymerase chain reaction-based analysis of M. oryzae.     

黄淮区粳稻抗稻瘟病基因Pi-ta、Pi-b、Pi54、Pikm的分子检测

利用水稻稻瘟病抗病基因Pi-ta、Pi-b、Pi54 和Pikm的功能标记对2016年山东省水稻中晚熟组区试、机插秧组区试的32个参试品系及连云港农业科学院科企水稻联合体黄淮粳稻区试16个品系进行了分子标记检测,结合稻瘟病抗性接种鉴定,对基因型与表型进行相关性分析。结果表明48个品种中携带Pi-ta、Pi-b、Pi54和Pikm抗性基因的品种数分别为15个、25个、26个和21个,其中鲁资稻7号、连粳14JD24含有4个基因的抗性等位基因,YS-6-6、济稻1号、D400等13个品种分别含有3个基因的抗性等位基因,临稻10号、丰稻2号、天和糯303等8个品种不含抗性等位基因。稻瘟病鉴定结果表明,48份品种中,济稻1号、圣稻072、连粳14JD24等4个品种表现中抗（MR）;临稻10、YS-6-6、圣稻053等26个品种表现中感（MS）;晶稻180、临13-105、圣稻504等15个品种表现感病（S）;H11-15、润农9号、晶稻160表现高感（HS）。Pi-ta、Pi-b、Pi54、Pikm 4个抗性基因已在黄淮区粳稻抗稻瘟病育种中得到广泛应用。其中Pikm与稻瘟病抗性综合指数存在显著相关性（r=0.477 5,P<0.01）。     

我国东北稻区稻瘟病的研究进展

东北水稻种植区是我国粳稻的主产区,长期以来稻瘟病是生产中危害最严重的病害之一。本研究就近30年来东北稻区稻瘟病菌优势种群和优势小种变迁,主栽品种抗性进行了综述,分析了已鉴定的稻瘟病抗性基因在东北稻区的利用价值,同时对该地区稻瘟病研究存在的问题与今后的研究方向进行了讨论,以期为水稻抗稻瘟病的育种提供参考。     

Cloning and in silico Mapping of Resistance Gene Analogues Isolated from Rice Lines Containing Known Genes for Blast Resistance

We amplified resistance gene analogues (RGAs) from the genomic DNA of 10 rice lines having varying degree of resistance to Magnaporthe grisea by using degenerate primers and various RGAs were mapped in silico on different rice chromosomes. The amplified products were grouped into 3–8 restriction fragment length polymorphic classes by using Mbo1 and Alu1 restriction enzymes. Of 98 RGAs obtained in this study, 65 RGA clones showed more than 95% homology with various RGAs sequences present in the GenBank. Phylogenetic analysis of these RGAs formed 11 groups. Using sequence homology approach, RGAs isolated in this study were physically mapped on 23 loci on chromosomes 1, 2, 3, 4, 5, 6, 7, 8, 10, 11 and 12. Twenty RGAs were mapped near to the chromosomal regions containing known genes/QTLs for rice blast, bacterial leaf blight and sheath blight resistance. Thirty‐nine RGA sequences also contained open reading frame representing signature of potential disease resistance genes.     

Bioinformatics Analysis of Disease Resistance Gene <i>PR1</i> and Its Genetic Transformation in Soybeans and Cultivation of Multi-resistant Materials

In agricultural production, a single insect-resistant and disease-resistant variety can no longer meet the demand. In this study, the expression vector pCAMBIA-3301-PR1 containing the disease-resistant gene PR1 was constructed by means of genetic engineering, and the PR1 gene was genetically transformed to contain the PR1 gene through the pollen tube method. In CryAb-8Like transgenic high-generation T₇ receptor soybean, a new material that is resistant to insects and diseases is obtained. For T₂ transformed plants, routine PCR detection, Southern Blot hybridization, fluorescence quantitative PCR detection, indoor and outdoor pest resistance identification and indoor disease resistance identification were performed. The results showed that there were 9 positive plants in the routine PCR test of T₂ generation. In Southern Blot hybridization, both PR1 and CryAb-8Like genes are integrated in soybeans in the form of single copies. Fluorescence quantitative PCR showed that the expression levels of PR1 and CryAb-8Like genes are different in different tissues. The average expression levels of PR1 gene in plant roots, stems, and leaves are 2.88, 1.54, and 5.26, respectively. CryAb-8Like genes are found in roots, stems, and leaves. The average expression levels were 1.36, 1.39, and 4.25, respectively. The insectivorous rate of the CryAb-8Like gene in outdoor plants with positive insect resistance identification was 3.78%. The disc partition method was used indoors for pest resistance identification, and the bud length of transformed plants increased significantly. The average mortality rate of untransformed plants in indoor disease resistance identification was as high as 56.66%, and the average mortality rate of plants transformed with PR1 gene was 10.00%, and disease resistance was significantly improved. Therefore, a new material with resistance to diseases and insects is obtained.     

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。     

二个粳稻品种抗稻瘟病遗传特性的分析

本文用累积分布曲线法对东农 363及农东415两个粳稻品种进行了抗稻瘟遗传分析,结果表明东农363对Hokul菌株的抗性是由一对显性抗性基因控制的,东农415对Ken53-33菌株的抗性是由两对互补的显性基因控制的;对Ina72菌株的抗性是由两对显性基因控制的,其中一对控制高抗反应,另一对控制中抗反应。两个杂交组合的正反交分析结果表明,水稻对稻瘟病菌的抗性遗传是由细胞核控制的,细胞质在抗瘟遗传中的作用在本试验的测试品种中并没有表现出来。 Abstract:By means of cumulative distribution curve methods,two Japonica varieties Dongnong 363 and Dongnong 415 were analysed for the inheritance of blast resistance.The results showed that the resistance of Dongnong 363 variety to Hokul blast strain was controlled by one dominant gene.The resistance of Dongnong 415 to Ken53-33 strain was controlled by two complementary dominant genes,to Ina72 strain was controlled by two dominant genes,one dominated over the high-resistant and the other over the middle-resistant.Genetic analysis of F3 plants of two reciprocal crosses showed that the resistance to the rice blast disease was controlled by nuclear gene,no cytoplasmic effect was found in the tested varieties.     

籼粳交新种质康丰A对稻瘟病抗性的遗传

康丰A是利用带有广亲和基因的籼粳亚种间杂交育成恢复系97gk419与恢复系明恢70杂交(恢复系×恢复系),所形成的胞质正常、雄性可育,而无恢复性的特殊变异新种质,再与野败胞质不育系连续回交转育成的具有特殊核遗传背景的新型水稻三系不育系。本研究通过接种不同地区的53个稻瘟病菌系,发现康丰A对华南稻区尤其是福建稻区的稻瘟病菌系具有广谱抗性。以康丰A(同型保持系康丰B)与普感品种丽江新团黑谷(LTH)杂交,获得杂交F1和F2,分别接种稻瘟病菌系81278、Guy11、FJ2009-66和98013A。接种鉴定和遗传分析表明,康丰A对4个菌系的抗性均由1对显性抗病基因控制。等位性测定表明,康丰A抗菌系81278的基因与已知抗病基因Pi-1、Pi-2、Pi-ta和Pi-3呈非等位关系,与Pi-ta(Pi-?)呈现连锁遗传,暂命名为Pi-kf1(t)。     

水稻恢复系M630稻瘟病抗性改良及其代谢组研究

稻瘟病是水稻的主要病害之一,改良水稻稻瘟病抗性对水稻生产、推广具有重要意义.本研究以携带广谱抗稻瘟病基因Pi9材料9311-Pi9为供体,水稻优良恢复系M630为受体,将杂交、回交与分子标记辅助选择和背景筛选相结合,获得改良恢复系M630-Pi9.主要农艺性状和稻米品质分析显示改良后的M630-Pi9及其杂交组合徽两优...     

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。     

水稻品种多样性遗传分析与稻瘟病控制

以2个籼型杂交稻——汕优63(A)和汕优22(B)、2个地方糯稻品种——黄壳糯(C)和紫糯(D)和3个粳稻品种——合系41(E)、楚粳12(F)和8126(G)为材料进行抗病基因同源序列(Resistance Gene Analogue,RGA)遗传分析。结果表明,杂交稻品种间以及粳稻品种间的抗性遗传较为相似,其相似系数分别为0．86和0．84。糯稻品种间以及糯稻、杂交稻和粳稻间的抗性遗传差异较大,相似系数为0．45。聚类分析表明,RGA结果与品种的系谱来源相吻合,与品种的田间抗性基本一致。根据品种的抗性遗传差异、农艺性状和经济性状的不同,在云南籼稻区的建水和石屏县以及温暖粳稻区的泸西县分别选用5种(A／C、A／D、B／C、B／D和A／B)和2种(E／C和E／F／G)不同的品种组合进行品种多样性混合间栽控制稻瘟病田间试验,结果表明,抗性遗传差异大(相似性：0．45～0．77)的5个品种混合间栽组合对稻瘟病有极为显著的控制效果,尤其是在混合间栽中高度感病的优质地方稻品种稻瘟病的发病率、病情指数均有极显著的下降,防治效果达54．47％～92．18％;遗传差异较小(相似性：0．84～0．90)的2个混栽组合混栽对稻瘟病的控制效果不明显,稻瘟病的防治效果在15．12％～25．54％。此外,品种抗性遗传和株高差异大的品种组合具有显著的增产效果,与品种净栽相比,平均增产539．0～900．0kg／ha,增幅5．57％-10．38％;品种抗性遗传和株高相似的品种组合没有增产效果。     

广东地方稻种暹罗占抗稻瘟病基因分析

广谱抗病基因的利用是控制稻瘟病最有效和最经济的方法。来源于华南的地方稻种暹罗占对稻瘟病菌表现出广谱抗性,以普感品种丽江新团黑谷为轮回亲本选育的暹罗占近等基因系NIL-XLZ对测试的44个不同来源稻瘟病菌的抗性频率为84.4%,其抗谱优于广谱抗瘟基因Pi2、Piz,与抗瘟基因Pi9和Pi50相近。为进一步了解暹罗占抗稻瘟病的遗传基础,以感病品种广恢290为母本、暹罗占为父本,构建了广恢290/暹罗占的F2遗传分离群体。选取致病谱较广的稻瘟病菌代表菌株GD08-T19对来源于广恢290/暹罗占的F1与F2个体进行了抗病遗传分析,结果显示F1个体全表现抗病,1760个F2个体的抗感分离比率为4.06∶1,表明暹罗占至少含有一个显性的抗稻瘟病基因。利用分布于Pi2、Pi1、Pita座位附近的44对SSR引物,对构建的抗/感基因池及遗传分离个体进行了分析,将暹罗占含有的一个抗瘟基因定位于水稻第6染色体Pi2/Pi9/Pi50基因家族区域247 kb的范围内。抗菌谱分析、基因特异性分子标记检测及测序分析结果表明:暹罗占含有广谱抗瘟基因Pi50。本研究结果为暹罗占在水稻抗病育种上的应用提供了重要依据。