玉米高密度SNP遗传图谱构建及其秃尖QTL定位

Construction of a high-density SNP genetic map and QTL mapping for ear tip barrenness in maize

【目的】构建在秃尖性状上存在明显差异的玉米高密度SNP遗传图谱,并对其秃尖QTL进行定位,为玉米秃尖分子机理研究及玉米抗秃尖品种选育提供理论参考。【方法】以无秃尖性状的自交系S群411331为母本、有秃尖性状的自交系综53313为父本,通过杂交和自交获得F2代群体。利用容量达10K的分子芯片获取大量SNP分子标记,从中筛选出具有多态性的SNP分子标记,构建F2代群体的高密度遗传图谱,并结合秃尖表型数据,分别采用QTL定位软件Rqtl和QTL.gCIMapping.GUI 1.1对相应的秃尖QTL位点进行鉴定及定位。【结果】F2代群体的平均秃尖长度为4.25 cm,说明其秃尖性状更偏向于父本综53313,秃尖整体较长,且秃尖变幅为0~6.1 cm,偏度和峰度值均位于-1.00~1.00,符合数量性状的分布特征。从2612个多态SNP分子标记中共筛选出2599个SNP分子标记成功构建遗传连锁图谱,总图距5624.38 cM,标记间平均距离2.27 cM。利用Rqtl共检测到6个QTL,分别位于第3、4、5、6、8和9染色体,其中加性效应和显性效应最大的2个QTL分别位于第6和8染色体,解释遗传变异的14.4%和16.3%。利用QTL.gCIMapping.GUI 1.1共检测到9个QTL,分别位于第1、4、5、6、8和9染色体,显性效应和加性效应最大的2个QTL分别位于第6和8染色体,与Rqtl检测结果相比,二者均在第8和9染色体的同一位置检测到1个QTL,在第5染色体检测到的QTL位置也较邻近,且效应最大的2个QTL均位于第6和8染色体;不同之处在于Rqtl在各染色体上只检测到1个QTL,而QTL.gCIMapping.GUI 1.1在第6和8染色体分别检测到2和3个QTL,在第1染色体检测到1个QTL,在第3染色体未检测到QTL,而Rqtl检测出的第1和3染色体QTL情况相反。【结论】玉米秃尖QTL分别位于第1、3、4、5、6、8和9染色体,其中主效QTL在第6和8染色体。

【Objective】QTL mapping for ear tip barrenness was made by constructing a genetic map with two maize inbred lines which had great difference on ear tip barrenness character,which would provide information at molecular level for mechanism research of ear tip barrenness and maize breeding with anti ear tip barrenness.【Method】With maize inbred line Squn 411331 as female parent,Zong 53313 as male parent,a F2 population was obtained by crossing and selfing.A high-density SNP genetic map was constructed by SNP molecular markers with polymorphism which were screened out from a cloud of SNP markers originated from 10K molecular chips.By using the QTL mapping softwares of Rqtl and QTL.gCIMapping.GUI 1.1 and combining phenotypic identification,QTL mapping of ear tip barrenness was conducted.【Result】The average length of ear tip barrenness of F2 population was 4.25 cm,which meaned that the characteristic of ear tip barrenness was more biased to the male parent Zong 53313.On the whole,the F2 population had longer ear tip barrenness with range of 0-6.1 cm.Both of the skew and kurtosis were located within-1.00 and 1.00,which fitted the distribution feature of quantitative trait.A genetic map of 2599 SNP molecular markers screened out from 2612 SNP molecular markers was constructed,which had total map distance of 5624.38 cM and average interval distance of 2.27 cM.By using Rqtl,six QTLs were located in chromosomes 3,4,5,6,8 and 9 respectively,among all the QTLs,two QTLs with the largest additive effect and dominant effect in chromosomes 6 and 8 could explain 14.4%and 16.3%of phenotypic variation respectively.While by using QTL.gCIMapping,nine QTLs were located in chromosomes 1,4,5,6,8 and 9 respectively,and the two QTLs with the largest dominant effect and additive effect were in chromosome 6 and 8.Compared with Rqtl test,there were one QTL in chromosomes 8 and 9 being detected at the same position by Rqtl,and the QTL in chromosome 5 were located nearby,and the two QTLs with the largest effect were both in chromosomes 6 and 8.The difference between the two software was that Rqtl could only detected one QTL in chromosomes,but QTL.gCIMapping.GUI 1.1 could detect two and three QTLs in chromosomes 6 and 8 respectively.In the mean time,one QTL was detected by QTL.gCIMapping.GUI 1.1 in chromosome 1,but none in chromosome 3,while a QTL was detected by Rqtl in chromosome 3,but none in chromosome 1.【Conclusion】The QTLs for ear tip barrenness are located in chromosomes 1,3,4,5,6,8 and 9,among which,the major QTLs are in chromosomes 6 and 8.