Heterosis for seedling traits in maize(Zea mays L.) revealed by quantitative trait Loci analysis of the triple testcross design | 利用三重测交群体剖析玉米苗期性状杂种优势的遗传学基础

Chinese. 为了探讨玉米苗期性状及其杂种优势形成的遗传学基础，以强优势玉米(Zea mays L.)杂交种组合豫玉22及其重组近交系为基础材料，采用三重测交(triple testcross, TTC)遗传交配设计，组配了包含312个测交后代的TTC群体，通过复合区间作图法检测到了30个控制发芽后第4天的最长根长、苗高、初生根数、根干重及叶干重的QTLs，并且在第2、3和7染色体上存在4个同时控制不同苗期性状的QTL区域。分析发现，在利用Z1和Z2数据定位出的22个QTLs中，以超显性位点最多(11个)，加性(5个)和部分显性较少(5个)，而显性最少(1个)。另外，还检测到8个QTLs与遗传背景之间的互作和16对不同标记间的互作。据此，我们提出超显性和上位性是玉米苗期性状及其杂种优势形成的主要遗传学基础。

English. To investigate the genetic basis of heterosis in maize seedling traits, highly heterotic maize(Zea mays L.) hybrid Yuyu22 and RILs(recombinant inbred lines) were used as basic population to construct TTC(triple testcross) population, which included 312 testcross progenies by using TTC genetic mating design. Thirty QTLs were detected for the longest root length (LRL), shoot height (SH), primary root number (RN), root dry matter weight (RDW) and shoot dry matter weight (LDW) by using composite interval mapping. And some QTLs for different seedling traits were found to be located on the same chromosome regions, and a total of 4 regions were detected, which distributed on chromosome 2, 3 and 7, respectively. Further analysis indicated that 22 QTLs were detected by using Z1 and Z2 data, which were classified as overdominant (11), additive (5), partially dominant (5) and dominant(1). Furthermore, 8 genome regions of QTL× genetic background interactions and 16 markers pairs with epistatic effects were detected. Collectively, we propose that overdominance and epistasis are the main genetic basis of maize seedling traits and their heterosis.