Seed1 Seed2 Seed3 Seed4 Seed5 Seed6 Seed7

Regulatory Interaction Maps of Arabidopsis Seed Development

The ratio of ABA and GA is of utmost importance for seed maturation and germination. FUS3 is discussed to promote ABA levels by increasing ABA synthesis and decreasing ABA catabolism (Gazzarrini et al. 2004, Nambara et al. 2000, Suzuki and McCarty 2008, Umezawa et al. 2006). FUS3 is a negative regulator of GA biosynthesis, as it has been shown to directly down-regulate GA biosynthetic enzymes (Curaba et al. 2003). LEC2 affects GA levels in a similar way (Curaba et al. 2003) although direct binding of LEC2 to promoters of GA biosynthetic genes was not shown yet. Via direct regulation of the MADS box TF gene AGL15, LEC2 promotes the activation of the GA2ox6 gene encoding a GA-degrading enzyme (Braybrook et al. 2006, Wang et al. 2004) and again, indirectly, the inhibition of the GA biosynthetic gene GA2ox6 (Zheng et al. 2009). A gene involved in cytokinin signaling is down-regulated by LEC2 (Braybrook et al. 2006). Auxin biosynthesis is positively regulated through the direct activation of auxin biosynthetic genes by LEC2 (Stone et al. 2008). Via direct regulation of IAA30, LEC2 as well as its target gene AGL15 affect auxin signalling (Braybrook et al. 2006, Zheng et al. 2009). ABI3 seems to be involved in auxin response during lateral root development (Brady et al. 2003, Suzuki et al. 2001).

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