Nair Sudha K, Molenaar Willem, Melchinger Albrecht E, Boddupalli Prasanna M, Martinez Leocadio, Lopez Luis Antonio, Chaikam Vijay
International Maize and Wheat Improvement Center (CIMMYT), ICRISAT campus, Patancheru, Greater Hyderabad, 502324, India.
Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, 70593, Stuttgart, Germany.
Theor Appl Genet. 2017 Jun;130(6):1113-1122. doi: 10.1007/s00122-017-2873-9. Epub 2017 Mar 18.
Among the qhir11 and qhir12 sub-regions of a major QTL qhir1, only qhir11 has significant effect on maternal haploid induction, segregation distortion and kernel abortion. In vivo haploid induction in maize can be triggered in high frequencies by pollination with special genetic stocks called haploid inducers. Several genetic studies with segregating populations from non-inducer x inducer crosses identified a major QTL, qhir1, on chromosome 1.04 contributing to in vivo haploid induction. A recent Genome Wide Association Study using 51 inducers and 1482 non-inducers also identified two sub-regions within the qhir1 QTL region, named qhir11 and qhir12; qhir12 was proposed to be mandatory for haploid induction because the haplotype of qhir11 was also present in some non-inducers and putative candidate genes coding for DNA and amino acid binding proteins were identified in the qhir12 region. To characterize the effects of each sub-region of qhir1 on haploid induction rate, F recombinants segregating for one of the sub-regions and fixed for the other were identified in a cross between CML269 (non-inducer) and a tropicalized haploid inducer TAIL8. To quantify the haploid induction effects of qhir11 and qhir12, selfed progenies of recombinants between these sub-regions were genotyped. F plants homozygous for qhir11 and/or qhir12 were identified, and crossed to a ligueless tester to determine their haploid induction rates. The study revealed that only the qhir11 sub-region has a significant effect on haploid induction ability, besides causing significant segregation distortion and kernel abortion, traits that are strongly associated with maternal haploid induction. The results presented in this study can guide fine mapping efforts of qhir1 and in developing new inducers efficiently using marker assisted selection.
在主效QTL qhir1的qhir11和qhir12亚区域中，只有qhir11对母本单倍体诱导、分离畸变和籽粒败育具有显著影响。在玉米中，通过用称为单倍体诱导系的特殊遗传材料进行授粉，可以高频触发体内单倍体诱导。几项对非诱导系×诱导系杂交分离群体的遗传研究在第1.04号染色体上鉴定出一个主效QTL qhir1，其对体内单倍体诱导有贡献。最近一项使用51个诱导系和1482个非诱导系的全基因组关联研究也在qhir1 QTL区域内鉴定出两个亚区域，命名为qhir11和qhir12；qhir12被认为是单倍体诱导所必需的，因为qhir11的单倍型也存在于一些非诱导系中，并且在qhir12区域鉴定出了编码DNA和氨基酸结合蛋白的假定候选基因。为了表征qhir1的每个亚区域对单倍体诱导率的影响，在CML269（非诱导系）与热带化单倍体诱导系TAIL8的杂交中，鉴定了在其中一个亚区域分离而在另一个亚区域固定的F重组体。为了量化qhir11和qhir12的单倍体诱导效应，对这些亚区域之间重组体的自交后代进行了基因分型。鉴定出了对qhir11和/或qhir12纯合的F植株，并与一个无叶测试系杂交以确定它们的单倍体诱导率。该研究表明，只有qhir11亚区域对单倍体诱导能力有显著影响，此外还会导致显著的分离畸变和籽粒败育，这些性状与母本单倍体诱导密切相关。本研究的结果可为qhir1的精细定位以及利用标记辅助选择高效开发新的诱导系提供指导。
