Mahmoud Ahmed A, Sukumar S, Krishnan Hari B
Plant Science Division, University of Missouri, Columbia, MO 65211, USA.
J Agric Food Chem. 2008 Jan 23;56(2):476-82. doi: 10.1021/jf071776n. Epub 2007 Dec 29.
Wild species offer a potential reservoir of genetic variation for crop improvement. Besides the valuable genes for disease resistance that the wild species have provided for rice improvement, recent studies have shown that these wild species could also provide favorable alleles for the improvement of yield and yield-related traits. The present study reports yet another potential of wild relatives of rice, which involves the improvement of seed protein content. A significant increase in seed protein content was observed in an interspecific hybrid between Oryza sativa ssp. indica and the wild species Oryza nivara. The hybrid showed a protein content of 12.4%, which was 28 and 18.2% higher than those of the parents O. nivara and IR 64, respectively. The increase in protein content was dependent on the genetic background of the rice variety used in the hybridization. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of seed storage proteins demonstrated that a significant increase in prolamins and glutelins was mainly responsible for the elevated protein content of the hybrid. Amino acid analysis of seed proteins revealed that the hybrid had net gains of 19.5% in lysine and 19.4% in threonine over the O. nivara parent on a seed dry weight basis. Molecular analysis indicated that the increase in protein content of the hybrid was not a result of chromosomal rearrangements or transposable element activation, at least in the chromosomal regions containing seed storage protein genes. A preliminary genetic analysis of the F 2 segregating population showed that the inheritance of the increased protein content was polygenic in nature. The development of this interspecific hybrid offers a great potential for selecting new rice cultivars that combine the high yield and superior cooking quality of IR 64 with improved seed protein content.
野生物种为作物改良提供了潜在的基因变异库。除了野生物种为水稻改良提供的抗病宝贵基因外，最近的研究表明，这些野生物种还可为产量及产量相关性状的改良提供有利等位基因。本研究报告了水稻野生近缘种的另一种潜在价值，即提高种子蛋白质含量。在栽培稻籼亚种与野生稻尼瓦拉稻的种间杂交种中，观察到种子蛋白质含量显著增加。该杂交种的蛋白质含量为12.4%，分别比亲本尼瓦拉稻和IR 64高28%和18.2%。蛋白质含量的增加取决于杂交中所用水稻品种的遗传背景。种子贮藏蛋白的十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析表明，醇溶蛋白和谷蛋白的显著增加是杂交种蛋白质含量升高的主要原因。种子蛋白的氨基酸分析表明，以种子干重计，杂交种的赖氨酸净增加19.5%，苏氨酸净增加19.4%，高于尼瓦拉稻亲本。分子分析表明，杂交种蛋白质含量的增加不是染色体重排或转座元件激活的结果，至少在含有种子贮藏蛋白基因的染色体区域是这样。对F2分离群体的初步遗传分析表明，蛋白质含量增加的遗传本质上是多基因的。这种种间杂交种的培育为选育新的水稻品种提供了巨大潜力，这些新品种将IR 64的高产和优良蒸煮品质与改良的种子蛋白质含量结合在一起。
