基于三重测交群体解析玉米株高与穗位高杂种优势QTL

QTL Analysis of Heterosis for Plant Height and Ear Position Using Triple Testcross Population in Maize

为检测玉米株高、穗位高杂种优势QTL,以121株intermated B73×Mo17(IBM)个体为基础群体,按照三重测交交配设计构建了三重测交群体,通过完备区间作图法对株高、穗位高杂种优势的主效QTL及互作位点进行了分析。在第9染色体上的2个紧密连锁的区段分别定位到了一个株高、穗位高杂种优势加性QTL位点,单个QTL的表型贡献率为14.3%和18.6%。该QTL可能同时对株高、穗位高杂种优势起作用。在第1、第3染色体上检测到2个株高杂种优势超显性QTL,可解释表型变异的9.0%~11.4%;在第1、第6、第8染色体上检测到5个穗位高杂种优势超显性QTL,可解释表型变异的6.6%~16.8%。进一步分析发现,2对加加上位性互作区段及2对显显上位性互作区段对穗位高杂种优势存在上位性贡献,加加互作效应及显显互作效应可共同解释表型变异的40.7%和26.8%。由此可知,加性、显性及两位点互作上位性共同对株高、穗位高杂种优势存在贡献。本研究检测到的主效QTL位点有助于株高、穗位高在杂种优势育种中的进一步应用。

In order to detect quantitative trait loci （QTL） of plant height （PH） and ear position （EP） in maize （Zea mays L.）, triple testcross （TTC） populations were constructed using 121 intermated B73×Mo17 （IBM） individuals based on to the TTC genetic mating design. The inclusive composite interval mapping was applied for identification of QTLs. One additive QTL was separately found for heteorosis of PH and EP in two regions linked tightly on chromosome 9 with the phenotypic variation being indicated by single QTL being 14.3% and 18.6 respectively, which was considered the same QTL contributing the heterosis of PH and EP simultaneously. In addition, two overdominant QTLs for heterosis of PH were identified on chromosomes 1 and 3, which could explain individually 9.0%-11.4% of total variation and five overdominant QTLs for heterosis of EP were identified on chromosomes 1, 6 and 8, with 6.6%-16.8% of total variation contributed by single QTL. Further analysis revealed two additive×additive epistatic interactions and two dominant×dominant epistatic interactions for heterosis of EP, which taken together could account for 40.7% and 26.8% of total phenotypic variation due to additive×additive epistatic effect and dominant×dominant epistatic effect. These findings suggest additive, dominance and epistasis interactions may play an essential role in determining the heterosis of maize PH and EP. The major QTL mapped in the present study facilitate the selection of PH and EP in maize breeding based on heterosis.