甘蓝型油菜苗期耐淹性状主基因+多基因遗传分析

Inheritance of Major Gene Plus Polygene of Water-Logging Tolerance in Brassica napus L.

长江中下游是中国油菜主产区,该地区油菜播栽期间雨水多,易产生湿害,造成产量下降。研究甘蓝型油菜苗期耐淹性的遗传规律,对选育耐淹性强油菜新品种,提高油菜产量意义重大。应用甘蓝型油菜品种WR-4(耐淹)和WR-5(不耐淹)杂交后代衍生的6个世代(P1、F1、P2、B1:2、B2:2、F2:3)群体为材料,全淹6 d后去水恢复生长,去水后第7天调查死苗率,以此为耐淹性指标,于2012和2013年对6个世代群体家系进行耐淹性鉴定。应用植物数量性状主基因+多基因混合遗传模型多世代联合分析方法对耐淹性进行遗传分析。结果表明,2个年度该家系群体苗期耐淹性的最适遗传模型分别是E-0和B-3,即2对加性-显性-上位性主基因+加性-显性-上位性多基因和2对加性主基因模型。由此可见,该家系群体甘蓝型油菜苗期耐淹性主要受2对主基因控制,主基因存在加性、显性和上位性效应。当有显性效应存在时(2012年),主基因显性效应值|h a|=0.3475,|h b|=0.0069,大于主基因加性效应值|d a|=|d b|=0.0036。B1:2、B2:2和F2:3群体的主基因遗传率(h2mg),2012年分别为36.25%、61.40%和61.84%,平均为53.16%;2013年分别为8.30%、30.48%和43.13%,平均为27.30%。2年平均环境变异占表型变异的59.77%。上述结果表明,甘蓝型油菜苗期耐淹性受2对主基因型控制,但环境对耐淹性状的表型影响较大。F2:3家系群体苗期耐淹性遗传率较高,因此育种上可在早期世代对耐淹性状进行选择。

The middle and lower reaches of Yangtze River is a main producing region of canola （Brassica napus L.） in China. However, canola in this region is subjected to water-logging during planting period to reduce yield. It is of importance to study the inheritance of water-logging tolerance for canola. In this paper a family lines population of six generations of P1, F1, P2, B1：2, B2：2, F2：3 derived from the cross of WR-4 （resistant）×WR-5 （non-resistant） was used to analyse genetic segregation by applying major gene plus polygene mixed inheritance model. The seedling mortality was recorded on the 7th day after logging-removing for plant recovery following six days full-submergence treatment of the seedlings in 2012 and 2013. The results showed that the seedling mortality was respectively fitted the genetic model of E-0 and B-3, i.e., two pairs of additive-dominant-epistatic major gene plus additive-dominant-epistatic polygene model and two pairs of additive major genes model. This result confirms that water-logging tolerance of seedling in this cross is controlled mainly by two major genes which expressed in the mode of additive-dominant-epistatic effects. While dominant effects expressed （2012） it gave a higher value of｜ha｜=0.3475,｜hb｜=0.0069 than the additive effect of the major genes which was ｜da｜=｜db｜=0.0036. In the populations of B1：2, B2：2, and F2：3, h^2mg was 36.25%, 61.40%, and 61.84%, respectively, with an average of 53.16% in 2012, and 8.30%, 30.48%, and 43.13%, respectively, with an average of 27.30%in 2013. Variance from environment effects was 59.77%of the total phenotypic variance on an average in two years. A conclusion could be made that water-logging tolerance of seedling in B. napus is controlled by two major genes but heavily affected by environment. Since a higher value of h^2mg was detected in F2：3 populations, selection in early generations might be an effective way for waterlogging tolerance breeding in B. napus.