Identification of Key Regulatory Genes for Sugar Metabolism in Sweet Corn
LIN Jianxin, LIN Jing, ZHANG Yang, LU Heding, CHEN Shanhu, LIAO Changjian*
In order to explore the change pattern of reducing sugar, soluble sugar and sucrose content and the key regulatory genes of sugar metabolism during the formation of sweet corn grains, sugar content and transcriptome analysis were performed at 10, 15, 20, 25 and 30 days after pollination. The results showed that reducing sugar content was the highest at 10 days after pollination, approximate 15 mg/g and it gradually decreased to approximate 4 mg/g. Whereas, the content of soluble sugar and sucrose increased firstly and then decreased, and reached the peak about 15 days after pollination, and then gradually decreased. PCA analysis showed that samples at 10 days could be obviously distinguished from samples at other time points, while samples at 15 days to 30 days did not show significant different, indicating that the development pattern of kernel at 10 days after pollination was significant different from that at 15 days after pollination. The gene expression levels at 10 days after pollination was used as control, a total of 221 genes in the metabolic pathways of starch and sucrose were analyzed, as results revealed that most of the annotated genes were not expressed or low expressed during kernel development. There were six annotated genes, Zm00001d045261 encoding starch synthase (EC 2.4.1.21), Zm00001d036608 encoding α-glucosidase (EC 3.2.1.20), Zm00001d033937 and Zm00001d045462 encoding granule-binding starch synthase (EC 2.4.1.242), Zm00001d050032 encoding glucose1-adenosine acyltransferase (EC 2.7.7.27) and Zm00001d045042 encoding sucrose synthase (EC 2.4.1.13), were highly expressed at 15 days after pollination, strongly indicating that these six coding genes play a key regulatory role in the process of glucose metabolism, which plays an important role in the formation of sweet corn quality. The results of this study provide important genetic resources for the molecular breeding of fresh sweet maize in the future.
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