Identification of Repressors of the Maturation Program during Embryogenesis
One lingering mystery has been the identity of the genes directly repressing the maturation program early in development.
Our microarray analysis indicated that ASIL1, HDA6/SIL1, and CLF were down-regulated in dcl1-15. These genes have previously been shown to repress the transcription of the LEC genes and other maturation-related genes in seedlings. Interestingly, several other histone deacetylases were down-regulated
(HDA5, -9, -10, and HDT1) as well as the closest homolog to ASIL1 (ASIL2). It has already been shown that ASIL1 binds to a GT-box, which is present in both the promoters of the LEC genes and of
the genes encoding storage products, regulating the program at least at two levels (Gao et al., 2009). We analyzed single and double mutant combinations of asil1-1, asil2-1, and sil1-1 and found that these genes redundantly repress the maturation program during early embryogenesis, downstream of miRNA targets.
Thus, our studies demonstrate, to our knowledge for the first time, that the same genetic mechanism negatively regulates seed
storage genes during early embryogenesis and seedling development.