Abstract
HSI2-subfamily B3 domain factors of Arabidopsis are required for repression of genes for embryogenesis and seed maturation after germination. Seeds of hsi2 hsl1 double knockouts express seed maturation genes after germination, accumulate seed storage proteins and oil in hypocotyls, and stop growth 7 days after germination1). Analyses of DNA-binding of HSI2 and transcripts in various mutants suggest that genes for seed storage proteins and seed oleosins are among the direct targets of HSI2. Chromatin of these genes is enriched with H3K27me3 inactive markers in mature plants. During germination of Col-0 seeds, mRNAs of these genes were lost within several days after germination, while H3K27me3 modification became prominent two weeks after germination. In hsi2 seedlings, these genes did not receive H3K27me3 modification even two weeks after germination. OleS3p::LUC showed transient LUC luminescence 36 hrs after germination in Col-0 seeds on medium containing luciferin. On the other hand, it showed continued expression after germination of hsi2 hsl1 seeds, suggesting that OleS3p::LUC enables us to monitor repression of seed maturation genes. 1)Tsukagoshi et al., PNAS 104: 2543 (2007).
