【作者】 李学慧；

【导师】 李玉玲；

【作者基本信息】 河南农业大学 ， 作物遗传育种， 2008， 硕士

【摘要】 高油玉米是20世纪人工培育的一种高附加值玉米新类型,具有全面的优良籽粒品质和较高的综合利用价值。由穗粒性状所决定的籽粒产量仍然是目前制约高油玉米杂交种大面积推广应用的主要因素。以往利用IHO和BHO高油玉米种质对产量及其构成因素进行了QTL定位研究。本研究选用具有ASK种质背景的高油玉米自交系GY220为父本,同时与两个普通玉米自交系8984和8622杂交构建了两个分别具有284个和265个F_2:3家系的作图群体(P1F_2:3,P2F_2:3),在洛阳春播和许昌夏播两种环境条件下进行田间试验,利用SSR分子标记构建高密度遗传图谱,采用复合区间作图法定位穗重、穗粒重、百粒重、穗长、行粒数、穗粗、穗行数和出籽率8个穗粒性状QTL,利用多区间作图法分析定位QTL间的上位效应,并通过条件QTL分析和多性状联合分析的复合区间作图方法探讨主要穗粒性状间及粒重与主要品质性状间的遗传关系,进一步揭示玉米产量构成因素的分子遗传基础,同时为分子标记辅助育种、QTL精细定位及克隆提供材料平台和理论依据。主要研究结论如下:1.利用两个相关群体P1F_2:3和P2F_2:3构建的遗传图谱分别包含185个和173个SSR多态性分子标记,其中83个标记相同。图谱总长度分别为2111.7 cM和2298.5 cM,相邻标记间平均距离为11.41 cM和13.29 cM。2.两个群体在两种环境条件下及合并分析共检测到与91个与8个穗粒性状相关的QTL,P1F_2:3和P2F_2:3群体分别检测到52个和39个QTL,单个QTL贡献率分别为4.8%-17.0%和4.2%-48.4%。P1F_2:3群体1个QTL在两种环境条件下及合并分析同时检测到,9个QTL在一种环境条件下及合并分析同时检测到;P2F_2:3群体5个QTL在一种环境条件下及合并分析同时检测到。定位QTL间互作较少,除P1F_2:3在洛阳点穗粗（umc2256～umc2118与umc2118～umc1746）、P2F_2:3合并分析的出籽率（qKR2-4-1与bnlg1194～umc1304）和许昌点的百粒重（qx100GW2-1-1与bnlg1792～umc1666）定位QTL存在较大的互作效应外,其余互作的效应值均较小。检测到的百粒重主效QTL ql100GW1-3-1/q100GW1-3-2、qx100GW1-6-1/q100GW1-6-1、qx100GW2-1-1/q100GW2-1-1、穗长QTL qlEL2-10-1/ qEL2-10-1、穗行数QTL qxERN1-3-2/qERN1-3-2、qlERN2-5-2/ qERN2-5-1和出籽率QTL qlKR1-7-1/qxKR1-7-1/qKR1-7-1贡献率较大且环境稳定性较好,可以作为进一步研究和实施分子标记辅助选择的主要目标QTL。P1F_2:3群体在第3、7和10染色体上及P2F_2:3群体在第1、5和7染色体上的相同标记或置信区间检测到的多个穗粒性状QTL,表现为热点分布。部分显性和超显性对穗粒性状的遗传起主要作用。3.两个群体没有在相同标记区间检测到控制同一性状的共同QTL,但在相邻标记区间检测到控制百粒重、穗粗和穗行数的QTL。q100GW1-1-2 （umc2237～phi039）和ql100GW2-1-1 （umc2237～bnlg1643）及qxERN1-5-2 （bnlg1879～umc1162）和qlERN2-5-1 （bnlg1879～umc1389）分别处在相同标记umc2237和bnlg1879的下方,可能为分别控制百粒重和穗行数的同一QTL;qxED1-1-1 （umc2237～phi039）和qED2-1-1（umc1395～umc2237）与相同标记umc2237连锁。4.两个F_2:3家系群体在两种环境条件及合并分析的穗重、穗粒重与除出籽率外的其它穗粒性状呈极显著表型正相关,百粒重与行粒数呈极显著的表型负相关,表明显著提高高油玉米产量需均衡协调各穗粒性状,尤其要协调百粒重和行粒数之间的关系。进一步对百粒重、穗行数和行粒数间进行多性状分析表明,检测到的百粒重主效QTL q100GW1-3-2和q100GW2-1-1在联合分析时也被检测到,且位于第1、3、5、6、7、8染色体上控制百粒重与行粒数和穗行数的QTL可能存在紧密连锁或一因多效。5.两群体百粒重与油分含量除P1F_2:3在许昌点表型相关不显著外,其余均呈显著或极显著的表型负相关。对百粒重与油分和淀粉含量的多性状分析结果表明,位于第1、3、5、6、7、8、10染色体上控制百粒重和油分或淀粉含量的QTL可能存在一因多效或紧密连锁。剔除油分和淀粉含量对百粒重的影响,对百粒重进行条件QTL分析结果表明,油分和淀粉含量对百粒重均有较大影响,但q100GW2-1-1和q100GW1-6-1基本不受油分含量的影响,且在百粒重与油分的多性状联合分析和以往研究中也被检测到,对其实施分子标记辅助选择可以在提高百粒重的同时,对油分含量影响较小,从而在一定程度上克服表型选择存在的问题。更多还原

【Abstract】 High-oil corn was a new type of high value-added corn by artificial cultivation in the 20th century with its comprehensive kernel nutritional quality traits and higher value. At present, grain yield determined by ear-kernel characters was still a main limitation in the large scale utilization of high-oil corn hybrids. Previous researches about QTL mapping for grain yield and its components have been conducted with IHO and BHO high-oil corn germplasms. In this study, 284 and 265 F_2:3 family lines were respectively developed from two crosses between the same high-oil corn inbred GY220 with ASK germplasms and two normal corn inbreds, 8984 and 8622. The field experiments were conducted under two different environments, Luoyang in spring and Xuchang in summer. SSR markers were used to construct high-density genetic maps. Using composite interval mapping （CIM） method, QTL mapping was conducted under the two environments individually and conbined. The eight ear-kernel characters included grain weight （GW）, grain weight per plant （GWP）, 100 grain weight （100GW）, ear length （EL）, kernel number per row （RKN）, ear diameter （ED）, row number per ear （ERN） and kernel rate （KR）. The interactions among detected QTL were identified using multiple interval mapping （MIM） method according to the result of CIM method. Conditional QTL mapping and joint QTL analysis among main ear-kernel characters and grain weight with two kernel nutritional quality characters were done using CIM method of multiple traits analysis. Our objectives were to reveal the molecular genetic mechanism of grain yield components. These results will do great help in fine mapping QTL associated with ear-kernel characters and their map-based cloning, and in marker-assisted selection in high-oil maize breeding. The main results were as follows:1. For the two connected F_2:3 populations (P1F_2:3 and P2F_2:3 ), 185 and 173 pairs of SSR markers were selected respectively to construct the maize genetic linkage maps. The genetic distance was 2111.7 cM and 2298.5 cM, with an average of 11.41 cM and 13.29 cM , respectively. Only 83 pairs of markers were in common between the two connected populations.2. 91 QTL were detected for 8 ear-kernel characters using the two F_2:3 populations analyed under two environments individually and combined. 52 and 39 QTL were detected in P1F_2:3 population and P2F_2:3 population. Contribution of single QTL to phenotypic variation varied from 4.8% to 17.0% and from 4.2% to 48.4%, repectively. In P1F_2:3 population, only one QTL was detected under two different environments and in combined analysis. Nine QTL were detected under one environment and in combined analysis. In P2F_2:3 population, five QTL were detected under one environment and combination analysis. Most interactions among detected QTL were small, except for ED （umc2256～umc2118 and umc2118～umc1746） in Luoyang in P1F_2:3 population and KR （qKR2-4-1 and bnlg1194～umc1304） in combined analysis and 100GW （qx100GW2-1-1and bnlg1792～umc1666） in Xuchang in P2F_2:3 population. Major QTL for 100GW （ql100GW1-3-1/q100GW1-3-2, qx100GW1-6-1/q100GW1-6-1 and qx100GW2-1-1/q100GW2-1-1）, EL （qlEL2-10-1/qEL2-10-1）, ERN （qxERN1-3-2/ qERN1-3-2 and qlERN2-5-2/ qERN2-5-1） and KR （qlKR1-7-1/qxKR1-7-1/qKR1-7-1） with higher contributions and stability could be used as the main objective QTL in further studies and in MAS. Some QTL controlling several ear-kernel characters located at the same marker loci or in the same marker confidence intervals on chromosome 3, 7, 10 in P1F_2:3 population and 1, 5 7 in P2F_2:3 population, which showed hot regions. Partially dominance and over dominance played the most part role in the genetics of ear-kernel traits.3. No common marker interval associated with the same trait was detected in both populations, but some QTL associated with 100GW, ED and ERN were detected in adjacent marker intervals. q100GW1-1-2 （umc2237～phi039） and ql100GW2-1-1 （umc2237～bnlg1643）, qxERN1-5-2 （bnlg1879～umc1162） and qlERN2-5-1 （bnlg1879～umc1389） were located below the same marker umc2237 and bnlg1879, repectively. They might be common QTL associated with 100GW and ERN, repectively. qxED1-1-1 （umc2237～phi039） and qED2-1-1（umc1395～umc2237）were associated with the same marker umc2237.4. GW and GWP were positively correlated with other ear-kernel characters significantly in phenotype, except for KR under the two populations, while 100GW and RKN were negatively correlated significantly. Therefore, it was very important to coordinate different ear kernel traits for the improvement of grain yield in high-oil corn, especially between 100GW and RKN. The results of multiple traits joint analysis among 100GW, RKN and ERN showed that two major QTL （q100GW1-3-2 and q100GW2-1-1） detected in single trait ananysis were also detected. Moreover, the QTL on chromosome 1, 3, 5, 6, 7 and 8 controlling 100GW and RKN or ERN showed pleiotropy or tight linkage.5. 100GW and kernel oil concentration were negatively correlated significantly in phenotype, except in Xuchang in P1F_2:3 pupulation..Multiple trait joint analysis for 100GW with kernel oil concentration and 100GW with kernel protein concentration showed that the QTL on chromosome 1, 3, 5, 6, 7, 8 and 10 controlling 100GW and kernel oil concentration or kernel protein concentration showed pleiotropy or tight linkage. Excluding the influence of oil and starch concentration on 100GW, conditional QTL analysis showed that their 100GW was obviously affected by oil and starch concentration. But q100GW2-1-1 and q100GW1-6-1 were less affected by oil concentration. These two major QTL were also detected in multiple trait joint analysis for 100GW with oil concentration and in previous studies. Positive selection for these two QTL through MAS could increase grain weight, while oil concentration might be less influenced. Thus, the negative correlation between grain weight oil concentration could be reduced, and the problem of phenotypic selection could be overcome in some degree.更多还原