Combining ability and heterosis analysis for mineral elements by using cytoplasmic male-sterile systems in non-heading Chinese cabbage (Brassica rapa)

Abstract

Brassica vegetables are an important source of dietary nutrition. The nutritional quality of mineral elements is becoming one of the most important studied traits because of the year-round supply of vegetables in China. However, there are few reports about breeding and utilisation of mineral elements in non-heading Chinese cabbage (Brassica napus L.). Using two newly reported CMS (cytoplasmic male-sterile) lines of non-heading Chinese cabbage, we conducted incomplete diallel experiments to analyse heterosis, combining ability and cytoplasmic effects for mineral elements such as calcium (Ca), iron (Fe), magnesium (Mg) and zinc (Zn). Heterosis analysis of mineral elements indicated that the crossing combinations A1 (hau CMS) × C03, A2 (eru CMS) × C03 and A2 × C11 exhibited desirable positive effects of mid-parent heterosis and high-parent heterosis in terms of mineral element content that could be exploited for commercial purposes. Analysis of general combining ability (GCA) effects of the parental lines indicated that the tester C11 was superior for the improvement of the four mineral elements; CMS line A1 had greater GCA effects than CMS line A2 for Ca and Fe. The hybrid combinations A2 × C11, B × C05 and B × C12 showed positive specific combining ability (SCA) effects for the four mineral elements on overall performance. The analysis revealed that cytoplasmic effects of hau CMS and eru CMS were both positive for Ca and Fe, and that A1 had more obvious cytoplasmic effects than did A2. These results indicated that the two isonuclear, alloplasmic CMS lines of non-heading Chinese cabbage might be useful for improving the nutritional quality traits of cruciferous vegetables and for heterosis utilisation.