广西水稻地方品种核心种质稻瘟病抗性位点全基因组关联分析

稻瘟病是水稻重要病害之一,严重影响水稻的产量与品质。培育抗性品种是防治稻瘟病最经济、环保的方式。稻瘟病抗性基因的鉴定与挖掘是开展抗病育种的基础与前提。本课题组前期对419份广西水稻地方品种核心种质进行简化基因组测序,获得208,993个高质量SNP标记。本研究采用苗期喷雾接种方法,研究了该419份核心种质对7个稻瘟病生理小种的抗性,并根据表型和基因型数据,利用一般线性模型(general linear model,GLM)和混合线性模型(mixed linear model,MLM)进行全基因组关联分析。2种模型下共检测到20个位点,其中GLM检测到20个位点,MLM检测到1个位点,Chr12_10803913位点在2种模型下都检测到。17个位点与前人定位的基因/QTLs重叠,其余3个是新位点,分别为Chr3_18302718、Chr3_18302744及Chr5_10379127位点。在20个显著关联位点上下游各150 kb的基因组区域中共筛选出候选基因323个,初步确定8个候选基因与抗病相关,其中LOC_Os12g18360(Pita)、LOC_Os12g18729(Ptr)为已知克隆的基因,LOC_Os03g32100、LOC_Os03g32180和LOC_Os05g18090为新位点附近筛选到的候选基因。本研究结果为稻瘟病抗性位点挖掘与稻瘟病相关基因克隆提供了科学依据。     

Genetic diversity in barley landraces from Syria and Jordan

Summary Single-head progenies derived from barley landraces collected along the Fertile Crescent in Syria and Jordan were evaluated for agronomic, morphological, and quality traits in a typical barley growing area in Northern Syria. A large diversity was observed both between and within collection sites, and in most cases the variation was useful for breeding purposes. Single plant progenies were identified with larger yields and more desirable expressions of agronomic characters than the original landraces. The utilization of this material in a breeding program for dry areas is discussed.     

Genetic analysis and breeding use of blast resistance in a japonica rice mutant R917

R917, a japonica rice mutant with broad-spectrum of resistance to blast, was selected after treatment of the F₁ seeds from the cross between Chengte 232 and Xiushui 37 with 10 krad of ⁶⁰Co γ-ray. R917 was evaluated for blast resistance in multiple years and locations. It was resistant to 136 of 138 strains of Magnaporthe grisea collected from different regions in China with a resistance frequency of 98.55%, much higher than 86.13% and 10.15% of Chengte 232 and Xiushui 37. To analyze its inheritance of resistance to blast, R917 was crossed with the susceptible cultivar, Nonghu 6, and its two parents. It had a single dominant resistance gene to Chinese races ZB13, ZC15 and ZE3, nonallelic to those of Chengte 232 and Xiushui 37. When inoculated with 7 Japanese differential strains, R917 showed the same reaction pattern as Toride 1 and differed from the other differential varieties. But R917 was different from Toride 1 in its reaction to 7 Chinese strains. Allelism test indicated that the resistance genes between R917 and Toride 1 were nonallelic to Chinese races ZC15 and ZE3. R917 was a semi dwarf with strong stem, narrow and erect leaf, tight plant type and monogenic broad-spectrum resistance to blast. Several lines with desirable agronomic traits newly bred using R917 as a donor of blast resistance had the same broad-spectrum of resistance to blast as R917, indicating there was no linkage drag between the resistance gene and other important agronomic genes in R917. R917 has been used as a donor in rice breeding programs in China. This revised version was published online in July 2006 with corrections to the Cover Date.     

Durable resistance to rice blast disease-environmental influences

Summary Blast is one of the most serious diseases of rice worldwide. The pathogen,Pyricularia grisea, can infect nearly all parts of the shoot and is commonly found on the leaf blade and the panicle neck node. Host resistance is the most desirable means of managing blast, especially in developing countries. Rice cultivars with durable blast resistance have been recognized in several production systems. The durable resistance of these cultivars is associated with polygenic partial resistance that shows no evidence of race specificity. This partial resistance is expressed as fewer and smaller lesions on the leaf blade but latent period does not appear to be an important component. Partial resistance to leaf blast is positively correlated with partial resistance to panicle blast, although some cultivars have been found showing leaf-blast susceptibility and panicle-blast resistance. A diverse set of environmental factors can influence the expression of partial resistance, including temperature, duration of leaf-wetness, nitrogen fertilization, soil type, and water deficit. Because of the great diversity of rice-growing environments, resistance that proves durable in one system may or may not prove useful in another. In highly blast-conducive environments, other means of disease management must be applied to assist host-plant resistance.     

Genetic diversity and yield performance among T. Aman rice (Oryza sativa L.) landraces in Barishal region of Bangladesh

Journal of Crop Science and Biotechnology - Understanding genetic diversity of rice helps to improve its yield. Although many landraces of rice are grown in the coastal area of Bangladesh, their...     

Genetic diversity of high-molecular-weight glutenin subunit compositions in landraces of hexaploid wheat from Japan

The high-molecular-weight (HMW) glutenin subunit composition of seed storage protein of 174 Japanese hexaploid wheat (Triticum aestivum) landraces have been examined by using sodium dodecyl sulfate polyacrylamide gel electrophoresis system. Twenty four different, major glutenin HMW subunits were identified, and each of the landraces contained three to five subunits and 17 different glutenin subunit patterns were observed for 13 alleles in the landraces. On the basis of HMW glutenin subunits composition, Japanese landraces showed a specific allelic variation, close to Japanese commercial wheats in HMW glutenin subunits, different from those in alien hexaploid wheats. Further, it could be concluded that all common glutenin alleles can be found in the 174 landraces originated from Japan. The variation detected in the glutenin subunits is useful for variety identification, has a bearing on our understanding of hexaploid wheat genetic resource evolution in Japan, and raises questions concerning the nature of this genetic variation. This revised version was published online in July 2006 with corrections to the Cover Date.     

抗稻瘟病两系杂交早稻株两优02

株两优０２是湖南亚华种业科学研究院和株州市农科所合作用低温敏两用核不育系株１S与优质早稻父本ZR０２选配而成的两系杂交早稻组合，２００２年３月通过湖南省农作物品种审定委员会审定。１产量表现２０００－２００１年湖南省早稻区试每公顷平均产量７６４７kg，比金优４０２增产１６５kg，日产量６９kg，比金优４０２高１．８kg。２００１年南方稻区早稻区试平均产量７３８４．５kg／hm２，比金优４０２增产３３８．２kg，达极显著水平。２００１－２００２年在湖南、江西、广西等省区示范栽培０．７５万hm２，据各地测产验收平均单…     

广西水稻区试品种(组合)对稻瘟病的抗性评价

2003-2006年分别采用苗期喷雾接种和穗期注射接种的鉴定方法对476份水稻区试品种（组合）进行稻瘟病人工接种鉴定,鉴定结果未发现有抗级材料,表现中抗的有19份,中感61份,感78份,高感318份,分别占鉴定总数的3.99%、12.81%、16.38%和66.80%。     

New sources of rice blast resistance obtained from Thai indigenous upland rice germplasm

Upland rice production plays an important role in both household consumption and crop rotation. Until now, a blast resistant upland variety has not been released in Thailand. The bimodal pattern of rain distribution in Thailand’s upland rice production areas create a favorable environment for the outbreak of leaf blast when seedling-tillering, and neck blast within the heading stage. The use of genetically resistant cultivars has proven to be an effective way to cope with this problem. In this study, 256 indigenous upland rice plants were screened for blast resistance under greenhouse and field conditions. Ten indigenous upland rice varieties, ULR292, ULR242, ULR219, ULR162, ULR161, ULR134, ULR109, ULR098, ULR081, and ULR066, were identified as resistant to leaf blast disease in both natural infection and artificial inoculation, under greenhouse conditions. Additionally, six of the ten varieties, ULR162, ULR161, ULR134, ULR109, ULR098, and ULR081, were found to be resistant to neck blast under field conditions. These new sources of blast resistance identified from indigenous upland rice varieties proved more resistant than the check varieties, depicting their potential for further use in Thailand’s rice blast resistance improvement program.     

Indica-japonica differentiation in Chinese rice landraces

Summary Ninety Chinese rice landraces were examined with special reference to the indica-japonica differentiation in terms of traditional criteria, isozyme analysis and PCR analysis of the chloroplast DNA (cpDNA). Cultivars were separated into indica and japonica defined by a discriminant function (Z) based on key characters, as well as by isozyme genotypes. Most indica landraces had chloroplast DNAs with a deletion at the Pst-12 fragment, while most japonica landraces had cpDNAs without the deletion. Two traditionally recognized varietal groups in China, keng and hsien, corresponded largely to the respective japonica and indica revealed in our study. The results obtained in this study showed good agreement for classification of indica and japonica types by the three methods: discriminant analysis by Z value, isozyme analysis, and PCR analysis for cpDNA.     

Analysis of a major rice blast resistance gene in the rice restorer line Hanghui 1179

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating diseases of rice (Oryza sativa) worldwide. Identification and utilization of resistance genes in rice breeding is considered to be an effective and economical method to control this disease. Hanghui 1179 (HH1179) is a new native rice restorer line developed in South China. The hybrids derived from HH1179 show broad-spectrum resistance against rice blast in South China, and a further understanding of the genetic resistance in HH1179 will provide useful information for breeding resistant cultivars. In the present study, we used bulked segregant analysis combined with specific-length amplified fragment sequencing to identify a dominant gene from HH1179 that provides resistance against the rice blast isolate GD13-14. Association analysis indicated that the resistance gene is located on chromosome 6 and we mapped the target gene to a 100.8 kb region (between markers InDel-8 and RM19818) that contains the Pi2/Pi9/Piz/Piz-t/Pi50 gene cluster. Candidate gene prediction and cDNA sequencing indicated that the target resistance gene in HH1179 is Pi2. Our findings will be valuable for resistance breeding with restorer line HH1179.     

OsSAMS1在水稻稻瘟病抗性中的功能研究

稻瘟病是水稻最重要的病害之一,对农业生产造成巨大的经济损失。研究表明,水稻中S-腺苷-L-甲硫氨酸合成酶OsSAMS1参与了水稻衰老相关的进程,我们实验室前期利用转录组测序分析发现, OsSAMS1基因的表达水平受稻瘟病菌诱导后明显提高。然而, OsSAMS1是否参与水稻的免疫反应,尚未明确。基于此,本研究选取野生型ZH11为背景材料,通过构建OsSAMS1基因敲除突变体来探究该基因在水稻抗病中的功能。结果表明, OsSAMS1主要在水稻叶片中表达;且其表达明显受稻瘟病菌侵染所诱导。亚细胞定位结果显示,OsSAMS1在细胞膜、细胞质和细胞核内均有表达。通过接种稻瘟病菌发现,与对照相比,2个等位敲除突变体ossams1-1和ossams1-2均表现为更加感病,且体内病程相关基因的表达也明显更低,同时突变体中乙烯合成相关基因的表达也受到明显抑制。综上所述,OsSAMS1参与了水稻的免疫反应,且正调控水稻稻瘟病的抗性。本研究为深入揭示OsSAMS1在稻瘟病免疫反应的分子机理奠定了基础,并为稻瘟病抗病育种研究提供了基因资源。     

新疆冬小麦地方品种与育成品种基于SNP芯片的遗传多样性分析

新疆是我国西北重要的小麦优势产区和消费区。解析新疆冬小麦地方品种与育成品种之间的遗传多样性和亲缘关系,对新疆冬小麦育种中杂交组合的合理选配以及后代选择具有重要的指导意义。本研究利用小麦55K SNP(single nucleotide polymorphism)芯片对134份新疆冬小麦地方品种及54份育成品种进行全基因组扫描,估算其品种间的遗传距离,揭示其遗传多样性。结果表明,所有SNP位点的多态性比率达到95.62%(50,743/53,063)。每条染色体分布1068～2616个多态性位点,多态性标记在基因组间分布呈现A>B>D。188个品种间的两两遗传距离在0.002～0.723之间,平均为0.378。其中134个地方品种两两之间的遗传距离在0.002～0.400之间,平均为0.070; 54个育成品种两两之间的遗传距离在0.004～0.337之间,平均为0.114; 134个地方品种与54个育成品种之间的遗传距离在0.605～0.723之间,平均为0.699。聚类结果显示可将所有材料分为10个不同类群。综合SNP和系谱分析,育成品种与地方品种之间的遗传差异最大,其次...     

水稻抗稻瘟病基因的定位与克隆研究进展

摘 要：稻瘟病是水稻最主要的病害之一,对世界水稻生产和粮食安全带来了极大的影响。克隆和利用稻瘟病基因被认为是最为经济、有效和环保的策略。本文综述了近年来水稻抗稻瘟病基因定位与克隆、抗瘟基因的分子结构特点等方面取得的研究进展,同时对抗瘟基因在水稻抗病育种中的应用提出了展望。     

Identification of a major blast resistance gene in the rice cultivar 'Tetep'

Analysis of near‐isogenic lines (NILs) indicated the presence of a novel resistance gene in the indica rice cultivar ‘Tetep’ which was highly resistant to the rice blast fungus Magnaporthe grisea.‘Tetep’ was crossed to the widely used susceptible cultivar ‘CO39’ to generate the mapping population. A Mendelian segregation ratio of 3 : 1 for resistant to susceptible F₂ plants further confirmed the presence of a major dominant locus, in ‘Tetep’, conferring resistance to the blast fungal isolate B157, corresponding to the international race IC9. Simple sequence length polymorphism (SSLP) was used for molecular genetic analysis. The analysis revealed that the SSLP marker RM 246 was linked to a novel blast resistance gene designated Pi‐tp(t) in ‘Tetep’.     

Role of the rice blast resistance gene Pi-cd in rice (Oryza sativa) breeding programmes

A series of DNA markers for various agronomic traits may accelerate the success of marker-assisted selection in practical plant breeding programmes. Here, we developed DNA markers for the blast resistance gene Pi-cd. In this study, we examined the effects of the Pi-cd locus on not only blast resistance but also agronomic traits in agriculture. We developed three pyramiding lines (PLs) coupling Pi-cd with three blast resistance genes, pi21, Pi35 and Pi39. The effect of Pi-cd on blast resistance was dependent on the coupled resistance genes. Then, we evaluated the effects of Pi-cd on 13 agronomic traits. Amylose content and 1,000-grain weight showed significant differences between the PLs and current commercial varieties, which had no negative effects on agronomic trait values. Furthermore, we investigated the distribution of genotype for the Pi-cd locus among varieties of upland rice. The KT genotype specific to rice blast resistance may be predominant in the varieties. The results suggested that Pi-cd has the potential to be useful for improving blast resistance in rice breeding programmes.     

Genetic diversity of some surviving on-farm Italian common bean (Phaseolus vulgaris L.) landraces

This study was undertaken to estimate the level of variation among and within 33 local populations belonging to seven Italian common bean landraces, by analysing the polymorphism of seed storage proteins, simple sequence repeat (SSR) and amplified fragment length polymorphism (AFLP) molecular markers. The nutritional seed quality of the landraces studied was also investigated. Results showed that the landraces retain a considerable level of heterogeneity. Use of both biochemical and molecular approaches provided a picture of the genetic diversity of each landrace. Cluster analyses based on Nei's genetic distances and Jaccard's similarity index as defined by SSR and AFLP markers, respectively, showed that all populations clustered into two groups corresponding to the Andean and the Mesoamerican gene pools. Knowledge of the genetic structure of a landrace is fundamental in elaborating strategies, which involve the local farmers, allowing us to improve and, at the same time, safeguard the genetic integrity of landrace genetic resources.     

Genetic diversity of Phaseolus vulgaris L. and P. coccineus L. landraces in central Italy

The genetic diversity of 66 Phaseolus genotypes was investigated, which included 14 local varieties of Phaseolus vulgaris and nine local varieties of P. coccineus, collected in Marche, central Italy. Their genetic diversity was assessed using three types of molecular marker: inter simple sequence repeats (ISSRs), nuclear gene‐tagged simple sequence repeats (SSRs) and chloroplast simple sequence repeats (CpSSRs). Phaseolus vulgaris shows a higher genetic diversity than P. coccineus for the SSRs and CpSSRs, but not for the putative neutral ISSR markers. These data suggest that selection by farmers and adaptation to heterogeneous environments has maintained the diversity in landraces of the common bean. Comparing genetic diversity in Marche with that of the American controls reveals that 71% of the local P. vulgaris varieties in Marche are of Andean origin. The two gene pools of the common bean can be found on the same farm, and there is some evidence of past hybridization events between these two gene pools.     

Genetic diversity and population structure of Indian melon (Cucumis melo L.) landraces with special reference to disease and insect resistance loci

This study was aimed to examine the genetic diversity and population structure of Indian melon landraces with special reference to disease and insect resistance loci. Thirty‐six simple sequence repeat (SSR) markers along with seven markers at disease and insect resistance loci were used for this purpose on a panel of 91 accessions available at Indian Institute of Horticultural Research, Bengaluru, India. Model‐based structure analysis revealed the presence of four groups that were consistent with the results of principal coordinate analysis (PCoA). The delineation of populations was mostly based on geography with improved varieties as a separate group. Ten accessions have been identified to possess beneficial alleles at all the selected disease resistance loci and shall be useful for incorporating multiple disease resistance after phenotypic validation. The results obtained in the current study demonstrate the importance of the Indian melon group as a valuable genetic reservoir and the need to plan strategies for its conservation and utilization in breeding programmes.