【作者】 赵茂俊；

【导师】 潘光堂；

【作者基本信息】 四川农业大学 ， 生物化学与分子生物学， 2004， 博士

【摘要】 针对我国特别是西南地区玉米纹枯病发生日趋严重，已成为危害该区玉米的主要病害，而纹枯病的抗性资源缺乏，且抗玉米纹枯病遗传机制不十分清楚的实际情况，本研究从筛选抗玉米纹枯病的种质资源入手，利用现代分子标记技术对玉米纹枯病的抗性基因进行QTL定位，以期对抗玉米纹枯病的遗传变异规律有较深入的了解，从而为抗玉米纹枯病的育种奠定较为坚实的基础。通过研究，取得了以下主要结果： 1．对从全国各地收集到的45份玉米自交系进行连续两年的人工接种鉴定，结果发现高抗玉米纹枯病的自交系1份（CML270），中抗自交系12份（R15和R09等），中感自交系29份和高感玉米纹枯病自交系3份（478、ES40、D黄212）。其中，中抗玉米纹枯病自交系R15对纹枯病的抗性明显高于其他中抗自交系，而且还是四川农业大学玉米研究所选育出的“三高”自交系，对其进行较深入研究，不仅有助于对抗玉米纹枯病机制的了解，而且对玉米抗病育种和生产实践具有更重要意义。 2．以R₁₅（抗）和478（感）为亲本配制F₂分离群体为作图群体，构建了含146个SSR标记位点的遗传连锁图谱，覆盖玉米基因组1666cM，平均距离为11.4cM。利用F_2：3群体将玉米纹枯病的5个抗性QTL定位于第2、6、10染色体上。基因作用方式除第10条染色体上的QTL仅表现为加性效应外，其余均为部分显性，且所有效应均为负值，这意味着这些基因效应有利于增加后代的抗病性。5个QTL共解释表型总变异的28.92％，其中第2条染色体上的一个QTL能解释10％以上的表型变异，可认为是主效基因位点。所检测到的5个QTL位点与邻近标记的距离分别为10.00、3.90、2.91、1.90、3.50 cM，该定位结果可用于分子标记辅助选择。 3．本试验除利用复合区间作图法定位抗纹枯病的QTL外，同时还应用单因子方差分析法对F_2：3群体的抗病性作了QTL分析。结果发现两种分析方法所得结论一致性很好，在一定程度上进一步说明本研究所定位的5个抗性QTL结果的可靠性。 4．实验中还利用F_2：3群体定位了控制株高和穗位高的QTL基因位点，分别位于5、7和1、4染色体上。比较抗纹枯病的QTL与株高、穗位高QTL的定位结果发现，抗玉米纹枯病的QTL与控制株高、穗位高的QTL完全不同，显然它们是受不同位点的基因控制的，这从另一个方面证明确实存在抗玉米纹枯病的基因。也说明玉米感纹枯病并不是其矮化育种的必然结果，即在玉米的半矮化育种中，完全可能发现和培育具有一定抗性的优良品种 5．本研究所检测到的5个抗性QTL仅解释表型总变异的28.92％，这可能与所选的抗性亲本抗纹枯病的能力有关，也可能与所构建的遗传连锁图谱还不够十分饱和及环境的影响有关，在今后的继续研究中，仍需进一步扩大种质资源的筛选，进行多年多点及不同群体、不同世代的考察;构建更加饱和的连锁图谱，以利于进一步的精细定位及分子标记辅助选择更多还原

【Abstract】 It is because Banded Leaf and Sheath Blight (BLSB) is one of the most important diseases of maize in China,especially in the southwest ,the resources of resistance to BLSB are insufficient in our country, and hereditary variation regularity of resistance to BLSB is not very clear. Therefore, we had made systematic researches on screening of resistance resources and the modern molecular locating method such as QTLs’. The main results are followed.(1) Forty five maize inbred lines were evaluated for reaction to BLSB with artificial inoculation during a period two years. The results showed that CML270 was highly resistant to BLSB, and other 12 inbred lines include R15 and R09 were middle resistant. Further evaluated for reaction to BLSB to R15 and R09 through pot culture, the results showed that R15 was better than R09 at resisting BLSB. R15 was a "Three Height" inbred line bred by the Maize Research Institute in Sichuan Agriculture University.(2) The genetic linkage map was constructed with 146 SSR marker based on a maize population consisting of 229 F2 individuals from the cross Ris(resistant) x 478(susceptible), covering 1666cM on total ten chromosomes with an average interval length of 11.4cM with the method of composite interval mapping. Five QTLs conferring resistance to BLSB were detected on chromosomes 2,6and 10. The gene action for QTL on chromosomes 2, 6 was additive and QTL on chromosomes 10 was partially dominant .All QTLs could explain 28,92% of phenotypic variance .The QTL on chromosomes 2 was inferred as the major one.(3) Three other different methods of QTL mapping (single-marker analysis, composite interval mapping method and composite interval mapping method) were used to analyze the resistance to BLSB. The results showed that three methods had a similar conclusion. This denoted that the results were reliable.(4) 3 QTLs of plant height were detected, distributed 5 and 7 chromosomes respectively. There have no relevance compared with the results of QTL of BLSB. It showed that the QTL conferring resistance to BLSB is true existence.更多还原