關(guān)于大米香味的遺傳起源的研究發(fā)現(xiàn)了此前未知的遺傳變異，這可以讓科學家開發(fā)出對于特定文化的嗜好具有吸引力的香米品種。栽培稻是一種高度多樣性的物種,，擁有很長而且復雜的進化史。盡管basmati 和jasmine這樣的香米品種具有顯著的文化價值而且比非香米獲得了高得多的市場價格,，科學家對于香味背后的基因BADH2的祖先尚不清楚,。
Susan McCouch及其同事追蹤了在大多數(shù)水稻品種中產(chǎn)生香味的BADH2基因的等位基因或者說基因變異的遺傳和地理起源。通過測定242個不同的水稻品種的這一基因及其周圍區(qū)域的序列,，這組科學家發(fā)現(xiàn)了盡管這個等位基因存在于所有主要水稻品種中,，香味很可能起源于粳稻而非此前認為的秈稻。這組作者還發(fā)現(xiàn)了在研究中發(fā)現(xiàn)的香米栽培種之中的兩種缺乏BADH2基因的任何已知突變,，這提示水稻中可能還存在其他控制香味的基因,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS August 17, 2009, doi: 10.1073/pnas.0904077106
The origin and evolution of fragrance in rice (Oryza sativa L.)
Michael J. Kovacha, Mariafe N. Calingacionb, Melissa A. Fitzgeraldb and Susan R. McCoucha,1
aCornell University, Department of Plant Breeding and Genetics, Ithaca, NY 14853; and
bGrain Quality Nutrition and Postharvest Centre, International Rice Research Institute, Los Baños, Philippines
Fragrance in the grain is one of the most highly valued grain quality traits in rice, yet the origin and evolution of the betaine aldehyde dehydrogenase gene (BADH2) underlying this trait remains unclear. In this study, we identify eight putatively nonfunctional alleles of the BADH2 gene and show that these alleles have distinct geographic and genetic origins. Despite multiple origins of the fragrance trait, a single allele, badh2.1, is the predominant allele in virtually all fragrant rice varieties today, including the widely recognized Basmati and Jasmine types. Haplotype analysis allowed us to establish a single origin of the badh2.1 allele within the Japonica varietal group and demonstrate the introgression of this allele from Japonica to Indica. Basmati-like accessions were nearly identical to the ancestral Japonica haplotype across a 5.3-Mb region flanking BADH2 regardless of their fragrance phenotype, demonstrating a close evolutionary relationship between Basmati varieties and the Japonica gene pool. These results clarify the relationships among fragrant rice varieties and challenge the traditional assumption that the fragrance trait arose in the Indica varietal group.
