Gene Expression Profile of Sweet Corn Ears under Heat Stress

Abstract

Sweet corn is an important vegetable crop around the world. Heat stress is one of the limiting factors in the production of maize in southern China. Therefore, digital gene expression profile was used to investigate the global gene expression profiles in ear development of maize cultivar Yuetian 13 widely planted in Guangdong under heat stress. The results indicated that, in the distribution of total Clean Tags, high-expression tags with copy numbers larger than 100 were in absolute dominance whereas low-expression tags with copy numbers smaller than five occupy the majority of distinct tag distributions. In total, 949 differentially expressed genes were detected, including 705 and 244 of genes up-and down-regulated, respectively. Among them, 108 and 40 genes were up-and down-regulated at least 10-fold. Using maize Gene Ontology database, we categorized these genes into three main categories: cellular component, molecular function and biological process. A large proportion of differentially expressed genes distributed in cell, intracellular and membrane, related to catalytic, binding, hydrolase and oxidoreductase activities, and involved in metabolic, cellular structure and function, response to stimulus, transport and biological regulation, were valuable for investigating kernel and ear development. Under heat stress, the genes related to cell structure maintenance, photosynthesis, signal transduction, transcription factor, and response to stress had higher expression levels in ear. And six genes were randomly selected for confirming their expression patterns by quantitative RT-PCR. The result showed these expression patterns basically consistent with the digital gene expression data. Further research should concentrate on characterizing the unknown function ones among differentially expressed genes.