Chaikam Vijay, Nair Sudha K, Martinez Leocadio, Lopez Luis Antonio, Utz H Friedrich, Melchinger Albrecht E, Boddupalli Prasanna M
International Maize and Wheat Improvement Center (CIMMYT), Nairobi, Kenya.
International Maize and Wheat Improvement Center (CIMMYT), Hyderabad, India.
Front Plant Sci. 2018 Oct 18;9:1527. doi: 10.3389/fpls.2018.01527. eCollection 2018.
For efficient production of doubled haploid (DH) lines in maize, maternal haploid inducer lines with high haploid induction rate (HIR) and good adaptation to the target environments is an important requirement. In this study, we present second-generation Tropically Adapted Inducer Lines (2GTAILs), developed using marker assisted selection (MAS) for , a QTL with a significant positive effect on HIR from the crosses between elite tropical maize inbreds and first generation Tropically Adapted Inducers Lines (TAILs). Evaluation of 2GTAILs for HIR and agronomic performance in the tropical and subtropical environments indicated superior performance of 2GTAILs over the TAILs for both HIR and agronomic performance, including plant vigor, delayed flowering, grain yield, and resistance to ear rots. One of the new inducers 2GTAIL006 showed an average HIR of 13.1% which is 48.9% higher than the average HIR of the TAILs. Several other 2GTAILs also showed higher HIR compared to the TAILs. While employing MAS for QTL, we observed significant influence of the non-inducer parent on the positive effect of QTL on HIR. The non-inducer parents that resulted in highest mean HIR in the early generation qhir1+ families also gave rise to highest numbers of candidate inducers, some of which showed transgressive segregation for HIR. The mean HIR of early generation qhir1+ families involving different non-inducer parents can potentially indicate recipient non-inducer parents that can result in progenies with high HIR. Our study also indicated that the HIR associated traits (endosperm abortion rate, embryo abortion rate, and proportion of haploid plants among the inducer plants) can be used to differentiate inducers vs. non-inducers but are not suitable for differentiating inducers with varying levels of haploid induction rates. We propose here an efficient methodology for developing haploid inducer lines combining MAS for with HIR associated traits.
为了在玉米中高效生产双单倍体（DH）系，具有高单倍体诱导率（HIR）且能很好适应目标环境的母本单倍体诱导系是一项重要要求。在本研究中，我们展示了第二代热带适应诱导系（2GTAILs），它是利用标记辅助选择（MAS），针对一个对HIR有显著正向效应的QTL，通过优良热带玉米自交系与第一代热带适应诱导系（TAILs）杂交培育而成。在热带和亚热带环境中对2GTAILs的HIR和农艺性能进行评估，结果表明2GTAILs在HIR和农艺性能方面均优于TAILs，包括植株活力、花期延迟、籽粒产量以及对穗腐病的抗性。新诱导系之一2GTAIL006的平均HIR为13.1%，比TAILs的平均HIR高48.9%。其他几个2GTAILs与TAILs相比也表现出更高的HIR。在利用MAS针对该QTL时，我们观察到非诱导亲本对QTL对HIR的正向效应有显著影响。在早期世代qhir1 +家系中导致最高平均HIR的非诱导亲本也产生了最多数量的候选诱导系，其中一些在HIR方面表现出超亲分离。涉及不同非诱导亲本的早期世代qhir1 +家系的平均HIR可能表明哪些受体非诱导亲本能够产生具有高HIR的后代。我们的研究还表明，与HIR相关的性状（胚乳败育率、胚败育率以及诱导系植株中单倍体植株的比例）可用于区分诱导系和非诱导系，但不适用于区分具有不同单倍体诱导率水平的诱导系。我们在此提出一种将针对该QTL的MAS与HIR相关性状相结合来培育单倍体诱导系的有效方法。
