Doubled haploid (DH) breeding based on in vivo haploid induction has led to a new approach for maize breeding¹. All modern haploid inducers used in DH breeding are derived from the haploid inducer line Stock6. Two key quantitative trait loci, qhir1 and qhir8, lead to high-frequency haploid induction². Mutation of the gene MTL/ZmPLA1/NLD in qhir1 could generate a ~2% haploid induction rate (HIR)^3,4,5; nevertheless, this mutation is insufficient for modern haploid inducers whose average HIR is ~10%⁶. Therefore, cloning of the gene underlying qhir8 is important for illuminating the genetic basis of haploid induction. Here, we present the discovery that mutation of a non-Stock6-originating gene in qhir8, namely, ZmDMP, enhances and triggers haploid induction. ZmDMP was identified by map-based cloning and further verified by CRISPR–Cas9-mediated knockout experiments. A single-nucleotide change in ZmDMP leads to a 2–3-fold increase in the HIR. ZmDMP knockout triggered haploid induction with a HIR of 0.1–0.3% and exhibited a greater ability to increase the HIR by 5–6-fold in the presence of mtl/zmpla1/nld. ZmDMP was highly expressed during the late stage of pollen development and localized to the plasma membrane. These findings provide important approaches for studying the molecular mechanism of haploid induction and improving DH breeding efficiency in maize.

^{基于体内单倍体诱导的双单倍体 (DH) 育种为玉米育种1}提供了一种新方法。DH 育种中使用的所有现代单倍体诱导剂均来自单倍体诱导剂系Stock6。两个关键的数量性状位点qhir1和qhir8导致高频单倍体诱导²。qhir1中MTL / ZmPLA1 / NLD基因的突变可产生约 2% 的单倍体诱导率 (HIR) ^3,4,5；然而，这种突变对于平均 HIR 为 ~10% ⁶的现代单倍体诱导剂来说是不够的。因此，克隆相关基因qhir8对于阐明单倍体诱导的遗传基础很重要。在这里，我们提出了以下发现：qhir8中非Stock6起源基因的突变，即ZmDMP，增强并触发了单倍体诱导。ZmDMP通过基于图谱的克隆进行鉴定，并通过 CRISPR-Cas9 介导的敲除实验进一步验证。ZmDMP中的单核苷酸变化导致 HIR 增加 2-3 倍。ZmDMP敲除触发单倍体诱导，HIR 为 0.1-0.3%，并且在存在mtl / zmpla1 / nld的情况下表现出将 HIR 增加 5-6 倍的更大能力。ZmDMP在花粉发育后期高度表达并定位于质膜。这些发现为研究单倍体诱导的分子机制和提高玉米DH育种效率提供了重要途径。