Pottorff Marti, Roberts Philip A, Close Timothy J, Lonardi Stefano, Wanamaker Steve, Ehlers Jeffrey D
Department of Botany & Plant Sciences, University of California Riverside, Riverside, CA, USA.
BMC Genomics. 2014 May 1;15(1):328. doi: 10.1186/1471-2164-15-328.
Heat-induced browning (Hbs) of seed coats is caused by high temperatures which discolors the seed coats of many legumes, affecting the visual appearance and quality of seeds. The genetic determinants underlying Hbs in cowpea are unknown.
We identified three QTL associated with the heat-induced browning of seed coats trait, Hbs-1, Hbs-2 and Hbs-3, using cowpea RIL populations IT93K-503-1 (Hbs positive) x CB46 (hbs negative) and IT84S-2246 (Hbs positive) x TVu14676 (hbs negative). Hbs-1 was identified in both populations, accounting for 28.3% -77.3% of the phenotypic variation. SNP markers 1_0032 and 1_1128 co-segregated with the trait. Within the syntenic regions of Hbs-1 in soybean, Medicago and common bean, several ethylene forming enzymes, ethylene responsive element binding factors and an ACC oxidase 2 were observed. Hbs-1 was identified in a BAC clone in contig 217 of the cowpea physical map, where ethylene forming enzymes were present. Hbs-2 was identified in the IT93K-503-1 x CB46 population and accounted for of 9.5 to 12.3% of the phenotypic variance. Hbs-3 was identified in the IT84S-2246 x TVu14676 population and accounted for 6.2 to 6.8% of the phenotypic variance. SNP marker 1_0640 co-segregated with the heat-induced browning phenotype. Hbs-3 was positioned on BAC clones in contig512 of the cowpea physical map, where several ACC synthase 1 genes were present.
The identification of loci determining heat-induced browning of seed coats and co-segregating molecular markers will enable transfer of hbs alleles into cowpea varieties, contributing to higher quality seeds.
种皮的热致褐变（Hbs）是由高温引起的，高温会使许多豆类的种皮变色，影响种子的外观和品质。豇豆中Hbs的遗传决定因素尚不清楚。
我们利用豇豆重组自交系群体IT93K - 503 - 1（Hbs阳性）×CB46（hbs阴性）和IT84S - 2246（Hbs阳性）×TVu14676（hbs阴性），鉴定出与种皮热致褐变性状相关的三个QTL，即Hbs - 1、Hbs - 2和Hbs - 3。在两个群体中均鉴定出Hbs - 1，其解释了28.3% - 77.3%的表型变异。SNP标记1_0032和1_1128与该性状共分离。在大豆、苜蓿和菜豆中Hbs - 1的共线性区域内，观察到几个乙烯形成酶、乙烯响应元件结合因子和一个ACC氧化酶2。在豇豆物理图谱重叠群217的一个BAC克隆中鉴定出Hbs - 1，该克隆中存在乙烯形成酶。在IT93K - 503 - 1×CB46群体中鉴定出Hbs - 2，其解释了9.5%至12.3%的表型变异。在IT84S - 2246×TVu14676群体中鉴定出Hbs - 3，其解释了6.2%至6.8%的表型变异。SNP标记1_0640与热致褐变表型共分离。Hbs - 3定位在豇豆物理图谱重叠群512的BAC克隆上，该克隆中存在几个ACC合酶1基因。
鉴定决定种皮热致褐变的基因座和共分离的分子标记将有助于将hbs等位基因导入豇豆品种，从而培育出更高品质的种子。
