Knoll Joseph, Ejeta Gebisa
Department of Agronomy, Purdue University,West Lafayette, IN 47907, USA.
Theor Appl Genet. 2008 Feb;116(4):541-53. doi: 10.1007/s00122-007-0689-8. Epub 2007 Dec 19.
Sorghum [Sorghum bicolor (L.) Moench] landraces from China generally exhibit excellent emergence and seedling vigor under cool conditions, and are being used as sources of genes for improvement of seedling cold tolerance in other cultivars. Marker-assisted selection (MAS) could expedite the introgression of genes from landraces into elite lines, however, only a few studies have empirically demonstrated efficacy of MAS for quantitatively inherited agronomic traits. In a preceding study we identified quantitative trait loci (QTL) for early-season performance in a recombinant inbred (RI) population, one parent of which was a cold-tolerant Chinese line, 'Shan Qui Red' (SQR). In this study, three SSR markers (Xtxp43, Xtxp51, and Xtxp211), each representing a QTL, were tested in two new populations: (Tx2794 x SQR F(3)) and (Wheatland x SQR BC(1)F(3)). Individual families were genotyped, and early-season field performance was measured for two years. Statistical analyses showed that the SQR allele of Xtxp43 had favorable effects on seedling vigor in both populations, and on emergence in the Tx2794 population. A large positive effect of the SQR allele of Xtxp51 was observed in the Tx2794 population for vigor and emergence. Slight genotype by environment interaction was observed for Xtxp51 in the Wheatland population. Marker Xtxp211 had small but significant effects on seedling vigor and emergence in both populations. Various interactions between loci were also significant. This study validated QTL markers in various genetic backgrounds, and demonstrated the utility of MAS for a quantitative trait, early-season cold tolerance, evaluated in the field.
来自中国的高粱[Sorghum bicolor (L.) Moench]地方品种通常在凉爽条件下表现出优异的出苗率和幼苗活力，正被用作改良其他品种幼苗耐冷性的基因来源。标记辅助选择（MAS）可以加快地方品种基因向优良品系的渗入，然而，只有少数研究通过实验证明了MAS对数量遗传农艺性状的有效性。在之前的一项研究中，我们在一个重组自交（RI）群体中鉴定了与早期表现相关的数量性状位点（QTL），该群体的一个亲本是耐寒的中国品系“山魁红”（SQR）。在本研究中，三个SSR标记（Xtxp43、Xtxp51和Xtxp211），每个标记代表一个QTL，在两个新群体中进行了测试：（Tx2794×SQR F(3)）和（Wheatland×SQR BC(1)F(3)）。对各个家系进行基因分型，并连续两年测定其早期田间表现。统计分析表明，Xtxp43的SQR等位基因对两个群体的幼苗活力均有有利影响，对Tx2794群体的出苗率也有有利影响。在Tx2794群体中，观察到Xtxp51的SQR等位基因对活力和出苗率有很大的正向影响。在Wheatland群体中，观察到Xtxp51存在轻微的基因型与环境互作。标记Xtxp211对两个群体的幼苗活力和出苗率有较小但显著的影响。位点之间的各种互作也很显著。本研究在不同遗传背景下验证了QTL标记，并证明了MAS在田间评估的数量性状——早期耐冷性方面的实用性。
