水稻纹枯病是一种全球范围影响水稻生产的重大疾病,美国农业研究局(ARS)的科学家发现了抗水稻纹枯病的遗传资源。
遗传学家安娜麦克朗,是阿肯色州斯图加特的美国农业研究局戴尔布珀斯国家水稻工程技术研究中心主任,是德克萨斯州博蒙特的水稻研究组的负责人,带领着科学家们进行水稻抗病基因组方面的研究。
植物病理学家Yulin Jia和斯图加特的同事在水稻纹枯病基因图谱测绘工作中取得突破,他们首次发现并证实遗传区域qShB9-2,对控制这种疾病产生重大影响。
在一个相关的项目研究中,斯图加特的遗传学家Georgia Eizenga筛选了73个有纹枯病抗性迹象的野生稻品种。7个入选品种显示不错,Eizenga的团队已经将它们与国内一些品种进行杂交,创造新的抗性种质。科学家们还开发了标准化的筛选技术,帮助快速准确地检测实生苗的水稻纹枯病,即所谓的“微室方法”。这种技术使用2升或3升塑料瓶创造一个湿度室以促进疾病的发展。这使得研究人员可以在短短7天内测量幼苗的疾病反应,加速从水稻栽培和野生近缘种确定新的抗源的过程。
与此同时,在博蒙特,遗传学家Shannon Pinson一直在研究来自国内水稻品种“莱蒙特”和中国品种“特青”的重组自交系基因图谱。她发现这些重组自交系18个染色体区域带有稻纹枯病抗性基因水,包括由Jia证实的qShB9 - 2的基因区域。在两个区域都表现出可测量的较大的纹枯病抗性效果。(生物谷Bioon.com)
生物谷推荐原文出处:
Agricultural Research Magazine May/June 2010 - Vol. 58, No. 5
Genomic diversity and introgression in O. sativa reveal the impact of domestication and breeding on the rice genome
Zhao, Keyan、Wright, Mark、Kovach, Michael、Reynolds, Andy、Tyagi, Wricha、 Kimball, Jennifer、Eizenga, Georgia、McClung, Anna、McClung, Anna、McClung, Anna、Ali, M. Liakat、Bustamante, Carlos、Mccouch, Susan、
Two different varietal groups of cultivated rice, Indica and Japonica, have been recognized since ancient times, suggesting rice was domesticated by man two different times from wild ancestral species. In general, indica rice and japonica rice have different plant and seed characteristics, and are adapted to different regions of the world. In 1982, a report suggested the two varietal groups could be further divided into five different groups identified as indica, aus, temperate japonica, tropical japonica, and aromatic. This study was conducted to look at the genotypic differences between a diverse collection of 395 rice cultivars (accessions) from the world"s rice-growing regions using a set of new DNA markers, called SNP (single nucleotide polymorphism) markers. Data analysis validated that the previously reported five major varietal groups were present in this collection and revealed that desirable traits were moved from one varietal group to another through crossing between the different groups, especially between the indica and japonica groups. Specifically, we identified chromosomal regions where a short plant height gene and a blast resistance gene from selected indica rice cultivars were recently incorporated into some tropical japonica rice cultivars; a desirable starch (amylose) gene from temperate japonica rice was incorporated into some indica rice cultivars; and the gene for longer grain length found in tropical japonica was incorporated into some indica rice cultivars. These results highlight how the new SNP markers can be used to genetically fingerprint important agronomic traits in individual rice cultivars. Ultimately, this information can be used by rice breeders to move desirable traits found in selected rice cultivars across varietal groups and develop improved rice cultivars.
Technical Abstract: The domestication of Asian rice (Oryza sativa) was a complex process and substantial ambiguity remains regarding the timing, number, and locations of domestication events. Deep genetic divergence between the two main varietal groups (Indica and Japonica) suggests at least two independent domestications from distinct wild populations. However, genetic uniformity surrounding key domestication genes across divergent subpopulations suggests cultural exchange of genetic material among ancient farmers and breeders. In this study, we utilize a novel 1,536 SNP panel genotyped across 395 diverse accessions of O. sativa to study genome-wide patterns of polymorphism, characterize population structure, and infer the introgression history of domesticated Asian rice. Our population structure analyses support the existence of five major subpopulations (indica, aus, tropical japonica, temperate japonica and aromatic/GroupV) consistent with previous analyses. Our introgression analysis shows that most accessions exhibit some degree of admixture, with many individuals within a population sharing the same introgressed segment due to artificial selection. Genes in these regions control a myriad of traits including plant stature, blast resistance, and amylose content. Admixture mapping and association analysis of amylose content and grain length illustrate the potential for dissecting the genetic basis of complex traits in domesticated plant populations. These analyses highlight the power of population genomics in agricultural systems to identify functionally important regions of the genome and to decipher the role of human-directed breeding in refashioning the genomes and population structure of a domesticated species.