水稻紋枯病是一種全球范圍影響水稻生產的重大疾病，美國農業(yè)研究局（ARS）的科學家發(fā)現了抗水稻紋枯病的遺傳資源。
遺傳學家安娜麥克朗，是阿肯色州斯圖加特的美國農業(yè)研究局戴爾布珀斯國家水稻工程技術研究中心主任，是德克薩斯州博蒙特的水稻研究組的負責人,，帶領著科學家們進行水稻抗病基因組方面的研究。
植物病理學家Yulin Jia和斯圖加特的同事在水稻紋枯病基因圖譜測繪工作中取得突破,，他們首次發(fā)現并證實遺傳區(qū)域qShB9-2,，對控制這種疾病產生重大影響。
在一個相關的項目研究中,，斯圖加特的遺傳學家Georgia Eizenga篩選了73個有紋枯病抗性跡象的野生稻品種,。7個入選品種顯示不錯，Eizenga的團隊已經將它們與國內一些品種進行雜交,，創(chuàng)造新的抗性種質,。科學家們還開發(fā)了標準化的篩選技術,，幫助快速準確地檢測實生苗的水稻紋枯病,，即所謂的“微室方法”。這種技術使用2升或3升塑料瓶創(chuàng)造一個濕度室以促進疾病的發(fā)展。這使得研究人員可以在短短7天內測量幼苗的疾病反應,，加速從水稻栽培和野生近緣種確定新的抗源的過程,。
與此同時，在博蒙特,，遺傳學家Shannon Pinson一直在研究來自國內水稻品種“萊蒙特”和中國品種“特青”的重組自交系基因圖譜,。她發(fā)現這些重組自交系18個染色體區(qū)域帶有稻紋枯病抗性基因水，包括由Jia證實的qShB9 - 2的基因區(qū)域,。在兩個區(qū)域都表現出可測量的較大的紋枯病抗性效果,。（生物谷Bioon.com）
生物谷推薦原文出處：
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.
