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。

研究从农杆菌介导法所获得的转Rt基因再生植株后代中得到大量不育株。用受体自交系18f红1授粉保种后，获得稳定不育的株系。通过两年、两点的种植，并结合与18f红）的多代回交以及与多个自交系的测交鉴定，对其遗传行为进行了初步研究。研究结果表明.其不育性状表现稳定．呈现出质核互作雄性不育的遗传特点。P（R检测及田间鉴定表明．外源基因是否整合到受体基因组内与不育性状的形成没有直接关系。雄性不育突变体的出现可能是组织培养过程所形成的体细胞克隆变异。

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。

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。

以航天诱变玉米细胞核雄性不育株的杂交F2及姊妹交后代群体为材料，对育性分离群体中两种育性植株的株高及生长动态进行了分析。结果表明，在整个生育期的不同发育阶段两种育性植株的株高差异均达极显著水平，在发育的早期阶段，二者差异较小，随着发育进程的推进，株高的差异逐渐加大。进一步对两种育性植株的株高增长曲线进行分析，发现二者的最大生长速度存在差别。

运用植物数量性状主基因+多基因混合遗传模型多世代联合分析的方法，对普通玉米自交系R08与A318杂交组合的P1、P2、F1、F2、B1:2和B2:2 6个世代群体的种子休眠性进行了分析。结果表明，它们的遗传符合1对负向完全显性主基因+加性一显性多基因模型。在F2:3、B1;2和R2:2三个家系世代，主基因方差分别0.9260,1.4176和0.5863; 多基因方差分别0.1184,0.1022和0.4623。主基因加性效应值为1.2172，显性效应值为1.2172；多基因加性效应值6 1．5028，显性效应值1．4334。主基因遗传率在F2:3、B1:2和B2:2 和 B2：2三个分离家系群体中为 44.8%～79.65%，多基因遗传率为5 74%～35．33%。其中，主基因遗传率在B1;2世代中最大，79.65%。

对利用一年生大刍草和四倍体多年生大刍草分别与玉米杂交选育出的一年生饲草玉米（scl）和多年生饲草玉米（sc3）生物产量和饲用营养成分进行分析，结果表明：scl和sc3鲜草年产量分别达115 620kg/h井、174 045kg/h井，是普通玉米的4～6倍；sc3的粗蛋白质（cP）和无氮浸出物（NFE）含量最高，分别为17 57%、48 73%，粗纤维（cF）含量最低，为21 65%，其粗脂肪（EE）和灰分（cA）含量分别为4 30%和7 75%；scl的营养成分含量分别为：（cP）14 73%、（cF）26 09%、（NFE）45 29%、（EE）4 78%和（cA）9 11%；化学营养类型分析表明scl与sc3分别属Nc型和N型，都是高产高饲用价值的新型饲草。

Two F2 populations with different kinds of spike derived from maize male sterility materials RP3 195(A)X S37(inbred line), which had been sib-bred for many generations, were used for sterility analysis and gene location. There were 138 and 247, plants in the two F2 populations respectively．Among the 326 pairs of microsat-ellite primers selected，56 were found polymorphic．Linkage analysis of F2 populations with the 56 pairs of prim-ers showed that microsatellite markers bnlg197 and umc l012 were linked with the male sterility gene．The genet-ic distance between marker bnlg197 and the male sterility gene in the two different F2 populations were 7 cM and 14.5 cM respectively. The genetic distance between marker umcl012 and the male sterility gene in the 138 plants was 28.5 cM．Thus the male sterility gene was located on chromosome 3L．

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.