A DMP-triggered in vivo maternal haploid induction system in the dicotyledonous Arabidopsis

Doubled haploid technology using inducer lines carrying mutations in ZmPLA1/MTL/NLD and ZmDMP1–4 has revolutionized traditional maize breeding. ZmPLA1/MTL/NLD is conserved in monocots and has been used to extend the system from maize to other monocots5–7, but no functional orthologue has been identified in dicots, while ZmDMP-like genes exist in both monocots and dicots4,8,9. Here, we report that loss-of-function mutations in the Arabidopsis thaliana ZmDMP-like genes AtDMP8 and AtDMP9 induce maternal haploids, with an average haploid induction rate of 2.1 ± 1.1%. In addition, to facilitate haploid seed identification in dicots, we established an efficient FAST-Red fluorescent marker-based haploid identification system that enables the identification of haploid seeds with >90% accuracy. These results show that mutations in DMP genes also trigger haploid induction in dicots. The conserved expression patterns and amino acid sequences of ZmDMP-like genes in dicots suggest that DMP mutations could be used to develop in vivo haploid induction systems in dicots. Mutations in the ZmDMP gene induce maternal haploids and facilitate breeding in maize. Now, a study extends this system of maize to dicots, showing that loss-of-function mutations in the Arabidopsis ZmDMP-like genes also induce maternal haploids.