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The B3 domain protein LEAFY COTYLEDON2 (LEC2) is required for several aspects of embryogenesis, including the maturation phase,
and is sufficient to induce somatic embryo development in vegetative cells. Here, we demonstrate that LEC2 directly controls
a transcriptional program involved in the maturation phase of seed development. Induction of LEC2 activity in seedlings causes
rapid accumulation of RNAs normally present primarily during the maturation phase. Several RNAs encode proteins with known
roles in maturation processes, including seed-storage and lipid-body proteins. Clustering analyses identified other LEC2-induced
RNAs not previously shown to be involved in the maturation phase. We show further that genes encoding these maturation RNAs
all possess in their 5′ flanking regions RY motifs, DNA elements bound by other closely related B3 domain transcription factors.
Our finding that recombinant LEC2 specifically binds RY motifs from the 5′ flanking regions of LEC2-induced genes provides
strong evidence that these genes represent transcriptional targets of LEC2. Although these LEC2-induced RNAs accumulate primarily
during the maturation phase, we show that a subset, including AGL15 and IAA30, accumulate in seeds containing zygotes. We discuss how identification of LEC2 target genes provides a potential link between
the roles of LEC2 in the maturation phase and in the induction of somatic embryogenesis.
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