Marri Pradeep Reddy, Sarla N, Reddy Laxminarayana V, Siddiq E A
National Professor Project, Directorate of Rice Research, Rajendranagar, Hyderabad 500 030, India.
BMC Genet. 2005 Jun 13;6:33. doi: 10.1186/1471-2156-6-33.
Cultivated rice (Oryza sativa L.) is endowed with a rich genetic variability. In spite of such a great diversity, the modern rice cultivars have narrow genetic base for most of the agronomically important traits. To sustain the demand of an ever increasing population, new avenues have to be explored to increase the yield of rice. Wild progenitor species present potential donor sources for complex traits such as yield and would help to realize the dream of sustained food security.
Advanced backcross method was used to introgress and map new quantitative trait loci (QTLs) relating to yield and its components from an Indian accession of Oryza rufipogon. An interspecific BC2 testcross progeny (IR58025A/O. rufipogon//IR580325B///IR58025B////KMR3) was evaluated for 13 agronomic traits pertaining to yield and its components. Transgressive segregants were obtained for all the traits. Thirty nine QTLs were identified using interval mapping and composite interval mapping. In spite of it's inferiority for most of the traits studied, O. rufipogon alleles contributed positively to 74% of the QTLs. Thirty QTLs had corresponding occurrences with the QTLs reported earlier, indicating that these QTLs are stable across genetic backgrounds. Nine QTLs are novel and reported for the first time.
The study confirms that the progenitor species constitute a prominent source of still unfolded variability for traits of complex inheritance like yield. With the availability of the complete genome sequence of rice and the developments in the field of genomics, it is now possible to identify the genes underlying the QTLs. The identification of the genes constituting QTLs would help us to understand the molecular mechanisms behind the action of QTLs.
栽培稻（Oryza sativa L.）具有丰富的遗传变异性。尽管存在如此巨大的多样性，但现代水稻品种在大多数重要农艺性状上的遗传基础却很狭窄。为了满足不断增长的人口需求，必须探索新途径来提高水稻产量。野生祖先物种是产量等复杂性状的潜在供体来源，有助于实现持续粮食安全的梦想。
采用高代回交法从印度的一个药用野生稻（Oryza rufipogon）材料中导入并定位与产量及其构成因素相关的新数量性状位点（QTL）。对一个种间BC2测交后代（IR58025A/药用野生稻//IR580325B///IR58025B////KMR3）的13个与产量及其构成因素有关的农艺性状进行了评估。所有性状均获得了超亲分离株。利用区间作图和复合区间作图鉴定出39个QTL。尽管在大多数研究性状上表现较差，但药用野生稻等位基因对74%的QTL有正向贡献。30个QTL与先前报道的QTL相对应，表明这些QTL在不同遗传背景下是稳定的。9个QTL是新发现的，首次报道。
该研究证实，祖先物种是产量等复杂遗传性状尚未开发的变异性的重要来源。随着水稻全基因组序列的可得性以及基因组学领域的发展，现在有可能鉴定出QTLs潜在的基因。鉴定构成QTLs的基因将有助于我们理解QTLs作用背后的分子机制。
