【作者】 陈晓东；

【导师】 孙东发；

【作者基本信息】 华中农业大学 ， 作物遗传育种， 2010， 博士

【摘要】 小麦是世界上最大的栽培作物,小麦生产对粮食安全问题起着十分重要的作用。自1979年Sasakuma和Ohtsuka首次报道小麦光敏感型细胞质雄性不育以来,一系列的光温敏小麦雄性不育系相继被发现。由于小麦光温敏不育系能克服细胞质不育系在小麦杂种优势利用上存在的细胞质负效应、恢复源窄、恢复力不强等缺点,因此,其在小麦杂种优势利用上的价值是不言而喻的。337S是迄今为止所发现的唯一对长日高温、短日低温均敏感的光温敏小麦雄性不育系。在湖北地区,提前或推迟播种都可使其小穗发育处于不育环境下达到高度不育,育性稳定,制种区域广；适期播种时,337S恢复可育,自交结实率达到50%以上；此外,337S具有优良的综合农艺性状等特点。本研究是在前人研究的基础上,主要针对其在短日低温不育条件下的遗传机制、遗传距离与杂优组合的关系及其光合速率的遗传特性进行了分析,定位了短日低温不育基因并对目标基因进行选择评价,主要结果如下：1.337S不育基因的遗传特征：以337S为母本与其它5个正常可育小麦品种(系)进行杂交,在短日低温环境下,扬花时,337S的穗部特征表现出与其它父本有着明显差异,其颖壳张开、柱头外露、透光,而其它父本材料及所有F1的穗部外观特征和育性表现完全正常。育性调查结果显示,337S高度不育,所有父本及F1组合均高度可育,F2群体中育性发生分离,这表明337S不育性状是由隐性基因控制。进一步对这5个F：分离群体的育性分离情况进行χ2检验,结果表明,所有组合的F2群体中可育个体和不育个体的分离比例均符合3：1的分离规律。由此推定,337S的短日低温不育性是受一对隐性基因控制。2.337S短日低温不育基因定位：根据遗传分析结果,采用SSR标记与BSA分析方法相结合,对短日低温条件下337S不育基因进行标记定位。对定位群体F2(337S/华麦8号)进行严格的育性筛选和鉴定,分别选取12株极端不育和12株完全可育的单株构建基因池,用分布于小麦基因组21条染色体上的228对微卫星引物进行检测并定位目标基因。结果,来自于1B染色体的4个SSR标记(Xgwm413、Xgwm273、Xgwm264和Xgwm11)、来自于5D染色体上的1个SSR标记(Xgwm182)及目的基因wptms3,构建成一个连锁群,总长85.1cM。其中,该不育基因wptms3被定位于Xgwm413和Xgwm182之间,与目标基因距离分别为3.2和23.5cM,且位于1B染色体短臂。利用与目标基因两侧紧密相邻的两个标记Xgwm413和Xgwm182进行标记基因型的单因素方差分析,结果也证实了连锁的可靠性。在本研究中Xgwm182被首次定位于1B染色体上,是一个新的标记位点。因此,本研究暂时将其命名为Xgwm182-1B,将其与以前的研究加以区分。3.利用连锁标记对目标基因进行选择：当单独利用标记Xgwm413进行选择时,其选择的准确度(AMAS)及效率(EMAS)分别为82.84%和86.85%,而对于标记Xgwm182来说,AMAS及EMAS分别仅为67.71%和71.25%。当用位于目标基因两侧的这两个标记同时对目的基因进行选择时,即使当两标记间的距离为26.7 cM时,AMAS值也可达到90.10%,然而,EMAS的值略微降低。4.遗传距离与337S的杂种优势组合的关系：利用40对SSR引物对337S等17个亲本材料之间进行遗传差异分析,估算各基因型之间的遗传距离(GD)。结果表明,所有小麦品种间的遗传距离总平均值为0.42,最小值为0.26,最大值为0.57,337S与其他16个亲本间的平均遗传距离为0.44。337S与其它16个亲本间的SSR标记遗传距离(GD)与F1表型值、杂种优势(MPH)及特殊配合力(SCA)的相关性分析表明,8个农艺性状中,主穗小穗数、单株穗数及单株产量与亲本间遗传距离正相关,其它5个性状与遗传距离呈负相关。在相关显著性水平上,只有单穗产量与遗传距离达到显著负相关(r=-0.5108,p<0.05)；在分析GD和MPH及SCA的相关性时,结果表明相关不显著。在产量方面,对于单株产量性状来说,GD与F1表型值和SCA表现正相关,但是与MPH呈负相关。表明选择遗传距离越大的亲本组合并非一定能获得越强的杂种优势效应,这也证明了杂种优势形成的复杂性。5.337S光合速率的遗传特性：用337S等6份亲本材料及以337S为母本组配的2份F1和1份F2,来对337S的光合速率进行遗传分析,结果表明,F1表现出一定的平均优势,但组合间差异较大。根据F2后代中的光合速率分布,经χ2检验,表现出受到一对主基因控制的趋势。更多还原

【Abstract】 Wheat is one of the largest cultivated crops and plays an important role in the food safety. Since Sasakuma and Ohtsuka first reported wheat photoperiod sensitive cytoplasmic male sterility, a series of photoperiod-temperature sensitive male sterile wheat lines have been discovered. As wheat photoperiod-thermo sensitive male sterile line can conquer alloplasmic effects, lack of restorer source and restoring ability derived from cytoplasmic male sterile system, it will be valuable in the utilization of heterosis in wheat production.337S is the only male sterile wheat line sensitive to both long daylength/high temperature and short daylength/low temperature so far. In Hubei province, the development of spikelet of 337S can be put in a sterile environment if the sowing time is advanced or delayed, and the sterility maintains stable.337S returns to be fertile and the self setting rate amounts to over 50% under appropriate sowing date. In addition,337S has a good integrative agronomic character. The present study mainly aimed at analyzing its genetic mechanism, relationship between genetic distance and heterotic groups, and genetic characteristic of photosynthetic rate under short daylength/low temperature. In this study, the short daylength/low temperature male sterile gene was mapped, selection of the target gene was conducted, and the main results were as follows:1. Genetic character of 337S:337S was crossed as a female parent with five fertile parents to produce five F1s and 5 F2sto analyze the genetic mechanism. Under short daylength/low temperature,337S exhibited apparent differences in phenotype from others during anthesis, with the glume opening and the stigma exserting whereas F1 progenies from the five crosses showed the same phenotype of the corresponding male parental lines. Fertility analysis indicated 337S appeared completely sterile while the other five male parental lines and all F1s were highly fertile. Fertility segregation appeared and fitted a ratio of 3:1 with Chi-square test in all the F2 populations. The sterility in 337S was thus governed by a single recessive gene under short daylength and low temperature. We temporarily designated this gene wptms3.2. Mapping of wptms3:According to the genetic analysis, the male sterile gene of 337S was located under short daylength/low temperature using the combination of SSR and BSA analysis. Serious fertility screening and identification among the F2 (337S/ Huamai 8) mapping population was performed. Equal amounts of DNA from 12 fertile and 12 sterile individuals were mixed to construct fertile bulk (BF) and sterile bulk (BS), respectively. A total of 228 SSR primers distributing among the wheat genome were used to identify the target gene and the results indicated four SSR markers from chromosome 1B (Xgwm413, Xgwm273, Xgwm264 and Xgwml 1), one from chromosome 5D (Xgwm182) and the target gene (wptms3) construct a linkage map of 85.1 cM. The male sterile gene wptms3 was thus mapped in an interval between Xgwm413 and Xgwm182 at a genetic distance of 3.2 and 23.5 cM, respectively, on chromosome arm IBS. One-way variance analysis using marker genotypes as groups showed that the fertility difference or variation between the groups divided by Xgwm413 and Xgwm182 was highly significant. This again verified the linkage between markers and the target gene. The marker Xgwm182 was first mapped on chromosome 1B, and thus a new marker locus in the present study. Therefore, we can tentatively designate the new marker as Xgwml82-1B, distinguishing it from previous reports.3. Selection of the target gene via linked markers:When selection based on single marker Xgwm413 was performed, AMAS and EMAS was 82.84% and 86.85%, respectively, while they were 67.71% and 71.25% for Xgwm182. When the two bracketing markers were used to select male sterile plants in the F2 progeny, AMAS reached 90.10% in spite of the distance between the two markers extending to 26.7 cM. However, EMAS slightly declined.4. Relationship of genetic distance (GD) and hybrid performance derived from 337S: Forty SSR markers distributed over all 21 wheat chromosomes were used to analyze genetic divergence among 17 parental genotypes and estimate the GD. The results indicated the averaged GD among the 17 parental genotypes was 0.42, ranging from 0.26 to 0.57. The averaged GD between 337S and the 16 parental cultivars was 0.44. Correlation of GD between 337S and the other 16 parents with F1 performance, MPH and SCA displayed three agronomic characters positively correlated with GD were spikelets of main head, head number per plant and yield per plant while the other five characters were negatively correlated. However, grain weight per head is the only trait that showed significantly negative correlation with GD (r=-0.3695, p<0.05). No significant correlation of GD with MPH and SCA was detected. These results suggested that high heterotic effects might not be firmly obtained if parental genotypes with large GD between them are chosen. 5. Genetic character of photosynthetic rate of 337S:6 parental genotypes, and 2 F1 and 1 F2 derived from 337S as a female parent were used to conduct genetic analysis of photosynthetic rate of 337S. The result showed F1 exhibited mid-parent heterosis but obvious discrepancy existed among combinations. According to photosynthetic rate distribution in the F2 population, Chi-square test showed the genetic model of photosynthetic rate of 337S was a single major gene conditioning mechanism.更多还原