DNA methylation plays an important role in gene expression regulation during biological development and tissue differentiation in plants. This study adopted methylation-sensitive Amplified fragment length polymorphism (AFLP) to compare the levels of DNA cytosine methylation at CCGG sites in tassel, bracteal leaf, and ear leaf from maize inbred lines, 18 White and 18 Red, respectively, and also examined specific methylation patterns of the three tissues. Significant differences in cytosine methylation level among the three tissues and the same changing tendency in two inbred lines were detected. Both MSAP (methylation sensitive amplification polymorphism) ratio and full methylation level were the highest in bracteal leaf, and the lowest in tassel. Meanwhile, different methylation levels were observed in the same tissue from the inbred lines, 18 White and 18 Red. Full methylation of internal cytosine was the dominant type in the maize genome. The differential methylation patterns in the three tissues were observed. In addition, sequencing of nine differentially methylated fragments and the subsequent blast search revealed that the cytosine methylated sequences were distributed in repeating sequences, in the coding and noncoding regions. Southern hybridization was used to verify the methylation polymorphism. These results clearly demonstrated the power of the MSAP technique for large-scale DNA methylation detection in the maize genome, and the complexity of DNA methylation change during plant growth and development. The different methylation levels may be related to specific gene expression in various tissues.

以玉米同核异质细胞质雄性不育系T黄早四、c黄早四、s黄早四以及保持系N黄早四为材料，比较研究了供试材料小孢子发育到单核期的线粒体atp6基因转录本保守区域的编辑位点。结果表明，DNA序列在T、c、s 3种胞质中完全一致，与N胞质相比除在27、28核苷酸处不同外，其余均一致，而各胞质cDNA序列却不尽相同。DNA和cDNA序列比较显示：atp6基因转录本保守区域内，N、s胞质中均存在19个编辑位点，T胞质存在22个，c胞质存在20个，它们相同的编辑位点有18个。大多数编辑位点都发生在密码子的第一、二位点上，可改变氨基酸的种类。18个相同的编辑位点大都为完全编辑，其中第1位点在各胞质中为部分编辑，第19位点除在N胞质中为完全编辑外其余胞质都为部分编辑。而各胞质特有编辑位点均以部分编辑的形式出现。由此可见，在玉米中atp6基因RNA编辑不仅具有序列特异性，同时还受到胞质背景的影响。通过分析还可看出，编辑的c残基前一个碱基多为嘧啶类碱基，编码氨基酸ser和Pro的密码子较其他类的密码子更易受到编辑，且植物RNA的编辑有着改变蛋白质疏水性、增加物种间保守性的倾向。

In order to understand the cytological mechanism of pollen abortion of genetic male sterile mutant induced by space night in maize, the sister cross population were used for sterility anal． ysis and cytological observation．Intact anther obselvation,isolated cells observation and paraffin sec-tion were adopted in this research．The results strawed that pollen abortion occured mostly in dyad stage of meiosis in genetic male sterile mutant. The dyad were degenerated with abnormal shape. In late aether developing stage,the tapetal cells were giant vacuolated and delayed degeneration．The pollen mother cells(PMC)began to dissolve and degenerate in a few anther before meiosis.

为研究太空诱变玉米核不育材料的不育基因所在位点，以雄性不育材料0.3SRP9×S37（自交系）的n代群体作为育性调查和SSR作图群体，用玉米第3染色体3.06位点的37对SSR引物进行差异筛选，结果表明分子标记umcl674，umc207（umcl644，dupssrl7，bnkl97，umc227l，umcl95l和bnkl047与不育基因表现为连锁遗传，进一步将不育基因定位在分子标记umc2076和umcl674之间，遗传距离分别为4.4 cM和3.7cM，并以此为基础构建了核不育基因区间的遗传连锁图，为下一步克隆该基因奠定了基础。

为探讨太空诱变处理玉米核不育材料的可育株、不育株花药的生理生化特性差异对可育、不育材料不同发育时期花药的可溶性糖、可溶性淀粉、蛋白质含量以及游离脯氨酸含量进行了测定。结果表明：太空诱变处理玉米核不育材料的可育株花药中的可溶性糖、淀粉、蛋白质以及游离脯氨酸含量均高于不育株花药的，且可育株花药中的可溶性淀粉、蛋白质和脯氨酸含量都随着花药的发育逐渐累积，在不育株花药中这些指标的变化不明显。