Analyzing Genes Differentially Expressed At The Endosperm Of Maize O2/o2 Near Isogenic Lines With CDNA Microarray And Isolation Of The O2 Promoter Binding Proteins

Maize is an important crop in China. The contents of lysine and tryptophan in the kernel of QPM increased double of the common maize. They are regulated by the recessive o2 gene. O2 is an important transcription factor in maize. It regulates expression of maize endosperm genes at transcription and translation level. The leading sequence regulates the expression of itself. The elucidation of the molecular mechanism of the physiological, biochemical and phenotypic change, such as suppression of the alcohol soluble protein in endosperm, the alteration of the amino acids metabolism and the pattern of the starch synthesis, low level of the carbohydrates, more susceptible to plant pathogens and reduction in protandry, may be of scientific significance and practical value in the QPM breeding.The differences at RNA transcription level of the maize dominant 02 and recessive o2 gene and endosperm development related genes were examined with cDNA microarray in two pairs of maize near-isogenic lines (NILs), Hz85(02/O2) vs Hz85(o2/o2) and S7913(O2/O2) vs S7913 (o2/o2), respectively. mRNA isolated from endosperm of the two pairs of NILs at different days after pollination (14, 16, 18DAP) was hybridized with the whole developmental phases of maize endosperm cDNA microarray early prepared. The main results were:(1) Eighty-seven clones detected in both pairs of NILs were sequenced. Bioinformatics analyses showed that these clones represent 24 TUGs (tentative unique genes), 12 unnamed proteins and 5 new sequences. The TUGs involved in several cell processes such as development, stress response, transportation, signal transduction, electron transfer chain, apoptosis, cell defense, metabolism, cell components and storage proteins.(2) Sequences homologous with zein protein family sequences encoded the zein family members such as 15kD, 19kD and its subunits, mutant 19kD, 19kD zein precursor, 22kD, γ-zein. The clones except the γ-zein are all down-regulated with the similar expression trend as the 02 mutant to o2. The expression trend is that the differential expression times is highest between the o2/o2 and 02/02 at the endosperm of 16 DAP, meaning the lowest expression; meanwhile the differential...