Clarification of molecular mechanism of rice mutant which shows non-Mendelian Inheritance induced by tissue culture

植物细胞培养通常在培养组织和再生植物中诱导遗传变异，包括大体形态、成熟度、产量和疾病反应的改变。此外，植物组织在体外培养系统中的传代可以诱导染色体水平上的一些变化，包括染色体数量、DNA甲基化程度和基因组拷贝数。为了弄清水稻非孟德尔遗传突变体的分子机制，利用dna芯片和蛋白表达系统对水稻植株的基因表达水平进行了分析。水稻有大约420个P450基因，这些基因可以产生油菜素内酯和赤霉素酸等植物激素。P450从水稻中分离得到。从水稻中克隆了CYP72A18 cDNA，并通过乙醇脱氢酶（ADHI）启动子在酿酒酵母AH22细胞中异种表达。从重组酵母细胞中分离的微粒体中含有CYP72A18，该基因被发现能催化除草剂白龙英酸(ω-1)-羟基化。我们还发现(ω-1)-羟基膦酸降低了对水稻幼苗的除草剂活性。基于这些结果，我们认为CYP72A18参与了水稻对除草剂天龙英酸的解毒

Plant cell culture often induces genetic variability in cultured tissues as well as in regenerated plants, which includes alterations in gross morphology, maturity, yield, and disease response. Furthermore, the passage of plant tissues through a culture system in vitro can induce several changes at the chromosomal level, which are in the number of chromosomes, in the extent of DNA methylation, and in the copy number of the genomes. In order to clarification of molecular mechanism of rice mutants which shows non-Mendelian Inheritance, we tried to analyze the gene expression levels of rice plant by using DNA-microarray and protein expression system. Rice has about 420 P450 genes which can make plant hormone such as brassinolides and gibberellic acids. P450 isolated from the rice Oryza sativa. The CYP72A18 cDNA was cloned from rice and heterologously expressed in Saccharomyces cerevisiae AH22 cells from the alcohol dehydrogenase (ADHI) promoter. Microsomes isolated from recombinant yeast cells contained the CYP72A18, which was found to catalyze the (ω-1)-hydroxylation of the herbicide pelargonic acid. We also show that (ω-1)-hydroxypelargonic acid has reduced herbicide activity against rice seedlings. Based on these results, we suggest that CYP72A18 participates in the detoxification of the herbicide pelargonic acid in rice plants