NATURAL VARIATION IN THE MATERNAL CONTROL OF SEED DORMANCY VIA A COMPLEX ENDOSPERM-EXPRESSED PHD FINGER TRANSCRIPTION FACTOR LOCUS
Penfield, S.1, Zhang, N.1 and Macgregor, D.R 1, 2
1Department of Crop Genetics, John Innes Centre, Norwich, UK
2Department of Biosciences, University of Durham, Durham, UK
Contact: Steven Penfield, email@example.com
Dormancy and dispersal are frequently linked characters which enable the mother plant to optimize the behavior of her progeny, spreading their germination over space and time. Given the ecological importance attached to the maternal control of seed dormancy, we optimized a Genome Wide Association Study to capture maternal environmental effects on seed dormancy. In addition to detecting previously known large effect loci at both Delay Of Germination 1 (DOG1) and DOG6, we found an additional locus on chromosome 2 specifically associated with regulation of germination after maturation at lower temperatures. This locus contains two PhD-finger transcription factors which are only expressed in the endosperm during early seed development, and conserved haplotypes correlating with primary dormancy implicated both genes in seed dormancy control. Loss of function analysis showed that this locus acts maternally to promote the development of strongly dormant states, and also to prevent high frequency seed abortion as previously observed in the endosperm-specific Polycomb Repressive Complex 2 (PRC2) medea mutant. Taken together, our data show that natural variation in the maternal control of germination exists in Arabidopsis, and suggest that a key mechanism is through maternal repression of gene expression in the endosperm.