不同选择方向回交改良玉米后代的出苗率和大斑病抗性

Germination Rate and Resistance to Northern Leaf Blight of the Backcross Generations Selected by Different Directions

在以08-641(R08)为轮回亲本的BC2F2材料中,以种子形状和颜色是否类似R08为标准,选出供体不同的两个典型材料,一个种子形状和颜色类似R08(编号为A,供体为CN962);另一个种子形状和颜色不类似R08(编号为B,供体为8065)。分别自交两代得到79个不同株系(BC2F4),A材料自交分离得到的株系群体称A株系群,B材料自交分离得到的株系群体称B株系群。把A、B株系群分别按上述标准进行双向分类,得到AR、ANR和BR、BNR共4个次级分类株系群。通过对这些不同分类群回交后代株系的田间出苗率与大斑病抗性鉴定和配合力分析,探讨不同选择方向对轮回亲本R08的改良效果。结果表明,79个回交后代株系中,26个株系的出苗率显著或极显著高于R08,29个高抗大斑病。不同选择方向的回交后代比较显示,对R08田间出苗率和大斑病抗性的改良,以种子形状和颜色不似R08为标准选择得到的回交后代株系优于以种子形状和颜色类似R08为标准选择得到的回交后代株系。因此,回交过程中在加强改良目标性状的基础上,采取多向选择策略可能有利于提高回交改良的育种效率。

Two donors CN962 and 8065 were used to improve the germination rate, resistance to northern leaf blight of the recurrent parent inbred line R08, and 2 typical ears coded as “A” and “B” was selected from their BC2F2 families, respectively. The A was similar to R08, and B was dissimilar to R08 in the shape and colour of the seed. These two ears were self-crossed twice and a bidirectional selection based on the similarity and dissimilarity in the shape and colour of seeds to R08 was carried out, respectively. A total of 79 lines （BC2F4） were developed and grouped as AR, ANR, BR and BNR. AR and ANR present the similar and dissimilar groups developed from A, BR and BNR present the similar and dissimilar groups developed from B, respectively. The results showed that 26 out of the 79 modified lines were significant or extremely significant higher than R08 in germination rate, and 29 lines of these lines were high-resistant to northern leaf blight. The dissimilar groups （ANR and BNR） were better than the similar groups （AR and BR） in germination rate and resistance to northern leaf blight. It concluded that during the process of backcross for improving maize inbred lines, the method that selecting the lines in the different directions could heighten the improve efficiency based on strict selection of target traits.