The Arabidopsis chromatin remodeling ATPase, CHR23, demonstrates a novel parental effect on seed size

Abstract

The genetics of seed size is confounded by the strong parental contributions to seed growth and development. For example, using Columbia (Col) ecotype pollen on C24 ovules produces an atypically large seed whereas the reverse cross produces a normal seed. Although Histone and DNA methylation pathways are both known to contribute to parental biases in seed size, specific realizators of the parental programs are not known. Using DNA methylation-sensitive AFLP, a screen was conducted for cis and trans-regulators of differential DNA methylation between Col and C24. A locus was identified, CHR23, that shares homology with SWI/SNF2-type chromatin remodeling ATPases. CHR23 has been implicated in cell growth and the regulation of gene expression, though most of its function remains uncharacterized. Crossing CHR23 mutants and wild-type Col Arabidopsis revealed larger seeds when CHR23 was the maternal factor, larger seeds were seen. Surprisingly, homozygous CHR23 seeds appeared in all ways normal. Analysis continued by isolating mRNA from crosses and using reverse transcriptase (RT) and PCR to amplify expression and identify genes. Next, we will verify CHR23 expression and further identify parental contribution to Arabidopsis seed size.