【作者】 向葵；

【导师】 潘光堂； Lana M.Reid； Xiaoyang Zhu；

【作者基本信息】 四川农业大学 ， 作物遗传育种， 2011， 博士

【摘要】 玉米是粮、经、饲三元作物。作为我国三大粮食作物之一,自新中国成立以来的近60年间,在解决温饱问题、保证粮食和饲料安全、发展国民经济以及缓解能源危机等方面发挥了重要作用。2009年,我国玉米种植面积已经超过水稻成为种植面积最大的作物,但是随着畜牧业和玉米深加工的发展,玉米作为粮经饲兼用作物的需求量日趋增加,玉米育种的任务仍然艰巨,而玉米改良的重点在可预见的将来仍集中在产量和品质的改良。粒用玉米的品质,除本身的蛋白质,赖氨酸、淀粉和脂肪含量外,另一个重要方面就是籽粒外观色泽。要保持籽粒外观色泽鲜美、洁净,就要求籽粒能迅速脱水和干燥。在一些高纬度高海拔地区,由于秋后气温迅速下降、雨水偏多、日照不足以及有效活动积温低,部分品种在收获时或遇到早霜时甚至不能正常成熟,或者引起籽粒霉烂；与此同时,玉米生产的全程机械化是世界和我国玉米生产的不可逆转趋势,玉米果穗脱水快和收获时籽粒含水量低,利用机械化收获可大大减少破碎率,减少产量损失；还可大大减少籽粒烘干的时间,节约能源和低碳,保护环境。鉴于此,玉米籽粒脱水慢、收获时籽粒含水量过高已成为世界玉米生产特别是高纬度或高海拔玉米生产区的主要问题。因此,籽粒快速脱水成为了玉米育种的一个重要的目标性状。本研究以5个自交系为材料,利用一种改良后的探针水分测定仪对全穗、苞叶、籽粒以及穗轴四部分的水分进行测定,并采用传统的烘箱法对这四部分的水分进行测定并与水分测定仪的测定值进行比较,优化了利用水分测定仪进行籽粒含水量测定的方法,并建立真实水分读数的标准曲线；以6个玉米自交系及8个F1为供试材料,对其抽丝后不同时间段进行水分测定,评价环境因子包括玉米热单位(CHU,Corn Heat Unit)及降雨量对籽粒脱水速率的影响,并提出利用水分测定仪进行快速脱水玉米选择的最佳时间；以上述研究结果为基础,通过对262份自交系进行鉴定,筛选出快速脱水自交系,供快速脱水育种用；以6个玉米自交系为材料,配制8个F1组合,对亲本及组合进行脱水性状的遗传分析,为组配快速脱水杂交种提供理论依据；对籽粒脱水速率与穗粒腐病抗性及农艺性状进行相关分析,探讨籽粒脱水速率与其它性状的相关性；搜集已发表的控制水分含量及抗穗粒腐病的QTL研究,通过元分析得出两个性状相关的真实QTL位点,并综合元分析结果,分析两个性状的一致性QTL区域。主要研究结果如下：1.利用水分测定仪(读数法)和烘干法测定的各部分含水量均具有显著相关性。其中全穗含水量和籽粒+穗轴含水量的相关系数最高,达到了0.98(2006年)和0.99(2007年)。用读数法进行含水量测定时,苞叶对全穗水分读数的影响不大。当籽粒含水量大于60%或者低于20%时,穗轴对籽粒含水量的影响较小；而当籽粒含水量位于20%至60%之间时,穗轴对籽粒含水量的影响相对偏大。当利用烘干法进行含水量测定时,穗轴对籽粒含水量影响较小。对全穗水分读数及籽粒含水量进行相关性分析,发现全穗水分读数可以利用线性模型(y=1.11x,R2＝0.79)来预测籽粒含水量。2.2007、2008及2009年间,降雨量及CHU均与籽粒含水量具有显著相关性。抽丝后的累积CHU可以利用模型y=c+dx2预测收获时的籽粒含水量。对不同的材料而言,籽粒含水量在抽丝后第4周开始出现差异,第5周开始出现显著差异。试验筛选出20个材料在抽丝后第5至6周(35-42天)具有较低的籽粒含水量,而其中的16个在收获时也具有较低的籽粒含水量。因此,使用水分测定仪MT808进行脱水速率测定时,最佳测定时间是从抽丝后的第5周至第8周。3.抽丝期对脱水速率具有显著影响,可使用分值进行籽粒快速脱水自交系筛选。具体的评分标准为：得分值=第5周含水量差异值+第8周含水量差异值-抽丝期差异值。其中,差异值=(总体平均值-该基因型平均值)／总体标准差。根据以上评定标准,对评价分数大于1的自交系作为快速脱水自交系进行选择。2008年筛选出22份自交系,2010年筛选出24份自交系。综合两年的研究结果,共筛选出5份在两年的脱水速率得分值均大于1的自交系,分别为：A679,B73-10,C0308、C0314和C0328。4.玉米籽粒脱水速率性状主要受加性遗传效应(87.48%)影响,也受少量非加性效应(12.52%)影响；籽粒脱水速率的广义遗传力(hB%)为79.16,狭义遗传力(hN%)为69.25,说明脱水速率是高度遗传的,实践中对籽粒快速脱水育种可进行早代选择；通过对不同组合的配合力效应值分析,发现C0431和C0441均表现出较高的GCA效应值,表明这两个自交系具有良好的育种应用价值,在籽粒快速脱水育种中可利用C0431和C0441组配组合。5.籽粒脱水速率与镰刀穗腐(籽粒接种)和水处理在0.1的水平上具有显著相关性。镰刀穗腐(籽粒接种)和串珠穗粒腐(籽粒接种),镰刀穗腐(籽粒接种)和水处理间均具有极显著相关性,相关系数分别为0.760和0.821。株高、穗位高和粒长与籽粒脱水速率均表现出显著负相关。其中,穗位高和脱水速率的相关系数最大(r＝-0.607),株高与脱水速率的相关系数其次(r=-0.577),粒长与籽粒脱水速率的相关系数为-0.535。秃尖长在0.1的水平上也与脱水速率具有显著相关性(r=0.521)。6.研究发现44个控制籽粒含水量的“一致性”QTL,并筛选出6个热点区域(bins 1.03,2.09,8.03,8.05,8.06和10.04)。控制穗粒腐抗性的“一致性”QTL有29个,主要分布的热点区域为bin 2.08和bin 3.04。在第2、第3、第6和第7条染色体上,共存在14个玉米籽粒含水量及穗粒腐病抗性“一致性”QTL的重叠区域,这些重叠区域主要集中在5个区段。在这些区段内共发现13个已知基因,可将这些基因归纳为5类：压力相关基因(htl,和abal),光合系统相关基因(lhcal、psbsl和ij1形态相关基因(eif5α和lg2),动力学相关基因rop6和sarl)以及生殖相关基因(dfr1和zmm7)。更多还原

【Abstract】 Maize (Zea mays L.) is the important food, industrial materials, feed and economic crop in China. As one of the three most important crops, it played an important role to solve many problems, such as food safety, energy sources, and so on. Maize became the biggest plant area in 2009 in China. However, becaust of the use develop of economic, the maize breeding is much more important than before. The mainly breeding goal included yield and quality. High kernel dry down rate is important to keep high quality. In mid-to short-season environments, the available seasonal thermal-time may be insufficient for grain maize to nature, there is a risk of insufficient time for kernel filling and drydown before the cooler fall weather slows development or an early frost occurs if these intermediate to late maturing hybrids do not flower until August. Based on this, high ear moisture (EM) at harvest became the main problem in all over the world, especially in short season region. So kernel dry down rate is the important goal in maize breeding. In this study, five inbred lines were used to measure the moisture reading in ear, husk, kernel and cob using modified moisture meter MT808, and compared the data with moisture content which measured by oven method, to develop a tool that could be used to non-destructively measure kernel moisture in the field, thereby allowing the selection of genotypes with faster kernel drydown rates; six inbred and eight hybrid lines were used to do the different period water measurements. We analysis the influence of environment factors included core heat units (CHU) and rainfall to kernel dry down rate, and measure the best time to select the fast dry down rate using MT808; identification the kernel dry down rate of 262 inbred lines, and select the inbred lines with fast dry down rate for breeding; six inbred and eight hybrid lines were used to do genetic analysis; the correlation between kernel dry down rate and ear rot resistance, the kernel dry down rate and the agronomic traits; all the published QTL results of ER reactions and GM in maize were collected, a meta-analysis was carried out to get the overlap domain of both traits to investigate the relationship between ER resistance and GM. The main results were summarized as followed:1. An Electrophysics moisture meter model MT808 was modified with two steel pins, it can be used for measuring maize ear moisture. Meter readings and relative kernel moisture, measured after destructive sampling and oven drying, were highly correlated. Total ear moisture readings (readings taken by inserting the pins thru the husk and into the kernels) could be used to predict kernel moisture, using the calibration curve y= 1.11x (R=0.79). Genotypic differences in kernel moisture were measurable using this meter. Husks influenced moisture measurements more in the early stages of ear development. The use of a modified hand-held moisture meter will improve the selection for kernel drydown in short-season corn hybrids.2. In 2007,2008 and 2009, ear moisture of six inbred lines and eight hybrid lines of corn (Zea Mays L.) were measured weekly using a modified Electrophics Moisture Meter model MT808 during the period from a week after silking date to harvest. Daily rainfall impacting on ear moisture dry down rate. During the filling time, CHU played an important role in ear moisture drydown. Calibration curve y= c+dx2 could be used to measure the moisture content in harvest using accumulation CHU after silking. During the first four weeks after silking, the ear drydown rates for all the test lines were not significant. However, at the time of 5 and 6 weeks after silking, ear drydown rate were different among lines. Most of lines which had lower ear moisture at 5 and 6 weeks after silking had lower kernel moisture at 8 weeks after silking where it was about harvesting time. The study shows that the suitable time for measuring ear moisture was between 5 and 6 weeks after silking date.3. A formula was used to measure the kernel dry down rate:Difference= (All average-genotype average)/all STDEV, and selection using scores. The score calculate as followed: score= difference in 5 week+difference in 8 week-difference in silk date. Based on above standard, we selected the fast dry down rate inbred lines with scores more than 1. There were 22 inbred lines were selected in 2008, while 24 inbred lines were selected in 2010. In total, there were five inbred lines had good performance in both two years, included:A679, B73-10, CO308、CO314 and CO328.4. The studies on six maize inbred lines and its eight F1 which derived from 4×2 incomplete diallel crosses demonstrate that:The kernel dry down rate mainly influenced by the additive genetic effect (87.48%), low influence by non-additive effect (12.52%) also exist; The broad sense heritability (79.16%) and narrow sense heritability (69.25%) also existed in kernel dry down rate, it showed that fast dry down rate was highly heritable, so selection of early generation should be carried out in fast dry down breeding; The results showed that CO431and CO441 had high generally combining ability, it can be used as good potential parents in fast dry down breeding.5. The disease severity in FGK and water check were significant correlated with kernel dry down rate in probability 0.1. FGK and FVK, FGK and water check had significant correlation, the correlation coefficient were 0.760 and 0.821, respectively. The plant height, ear height and kernel length were negatively correlated to kernel dry down rate. Among them, the correlation coefficient of ear height and kernel dry down rate was the most high one (r=-0.607), the correlation coefficient of plant height and kernel dry down rate was-0.577.6. Our purpose was to identify the genomic regions of maize in the control of ER resistance and GM, and the correlations between two traits. A meta-analysis was carried out using 241 quantitative trait loci (QTL) from 29 studies to propose meta-QTL (MQTL) on a high-density genetic linkage map (IBM 2 neighbors 2008). Twenty-nine MQTL were found for ER resistance, mainly located on chromosomes 3,6 and 7. The ER MQTL were clustered on two chromosome regions, bins 3.04 and 2.08. For GM content,44 MQTL were identified on all chromosomes except for chromosome 9. The GM MQTL were clustered on six active chromosome regions, including bins 1.03,2.09,8.03,8.05,8.06 and 10.04. Moreover,14 overlapping domains for ER MQTL and GM MQTL were observed on chromosomes 2,3,6 and 7, mainly focused on five active regions (bins 2.08-2.09,3.04,3.06,6.04-6.06 and 7.03-7.03). There were 13 genes in the overlapping domain between MQTL for GM and ER. These genes were divided into five classed:stress-related gene(htl and aba 1), photosystem-related gene (lhcal, psbsl and ijl), architecture-related gene (eif5a and lg2), dynamic-related gene (pdi8, tua5, rop6 and sar1) and seminal-related gene(dfrl and zmm7).更多还原