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

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 ArabidopsisZmDMP-like genes also induce maternal haploids. Doubled haploid technology using inducer lines carrying mutations in ZmPLA1/MTL/NLD and ZmDMP(1-4) has revolutionized traditional maize breeding. ZmPLA1/MTL/NLD is conserved in monocots and has been used to extend the system from maize to other monocots(5-7), but no functional orthologue has been identified in dicots, while ZmDMP-like genes exist in both monocots and dicots(4,8,9). Here, we report that loss-of-function mutations in the Arabidopsis thalianaZmDMP-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.