Studies Of Improving Elite Maize Hybrid Zhengdan958Using Two Major QTL For Oil Content

Maize oil is a highly valued vegitable oil as it has high levels of unsaturated fatty acids. In2010, maize became the top first crop in China when the plant area reached up to32.5million hectares. Among all the planted maize hybrids, Zhengdan958had the largest plant area, and thus increasing the kernel oil content in Zhengdan958will play a critical role in the increase of the added value in maize hybrids. In this study, two major QTL for oil content, qHO1and qHO6, were targeted for introgression of the favorable alleles from the high-oil inbred lines, By804, into two parents of elite maize hybrids Zhengdan958, Zheng58and Chang7-2, to increase the oil content in Zhengdan958using marker-assisted recurrent selection. In addition, the effects of two major QTL for oil content were further observed using the improved lines, providing the useful information for the commercial production of the improved Zhengdan958. The major results are as the following:1) For qHO6, the kernel oil content in the improved lines from Chang7-2and Zheng58reached up to5.0%and4.4%, and increased by19.6%and29.4%compared with the control, respectively. In addition, no significant changes were observed for yield related traits in the improved lines. These results indicate qHO6only affects the oil content while not yield related traits.2) For qHO1, the kernel oil content in the improved lines from Chang7-2and Zheng58reached up to4.77%and4.13%, and increased by11%and16%compared with the control, respectively. However,100-kernel weight in the improved lines from Chang7-2and Zheng58decreased by1.3g (5%) and1.76g (6%), respectively. Furthermore, significant changes were observed for ear row number in the improved lines from Zheng58.3) The field experiments in five locations in one year of the improved Zhengdan958for qHO6showed the oil content reached up to4.65%, and increased by20%compared with the control. No significant differences were observed for100-kernel weight between the improved Zhengdan958(36.01g) and control (35.95g). Further investigations showed no other traits in maize kernel and embryo changed significantly besides the embryo weight, which increase significant by0.003g (5.4%).4) The field experiments in five locations in one year of the improved Zhengdan958for qHO1showed the oil content reached up to4.43%, and increased significantly by13%compared with the control. Additionally, significant changes were observed for100-kernel weight (increased by1.14g) and ear row number, but not for no other yield related traits. Further investigations for the kernel and embryo related traits showed the kernel length, width and thickness in the improved Zhengdan958for qHO1significantly decreased by0.2,0.15and0.23mm, and embryo length and width increased by0.33and0.23mm, respectively. These results indicate the improved Zhengdan958for qHO1have significant changes both in kernel oil content, kernel and embryo related traits.