SCARECROW-LIKE 3 promotes gibberellin signaling by antagonizing master growth repressor DELLA in Arabidopsis

Zhong Lin Zhang, Mikihiro Ogawa, Christine M. Fleet, Rodolfo Zentella, Jianhong Hu, Jung Ok Heo, Jun Lim, Yuji Kamiya, Shinjiro Yamaguchi, Tai Ping Sun

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    248 Citations (Scopus)


    The diterpenoid phytohormone gibberellin (GA) controls diverse developmental processes throughout the plant life cycle. DELLA proteins aremaster growth repressors that function immediately downstream of the GA receptor to inhibit GA signaling. By doing so, DELLAs also play pivotal roles as integrators of internal developmental signals frommultiple hormone pathways and external cues. DELLAs are likely nuclear transcriptional regulators, which interact with other transcription factors to modulate expression of GA-responsive genes. DELLAs are also involved in maintaining GA homeostasis through feedback up-regulating expression of GA biosynthesis and receptor genes. However, the molecular mechanisms by which DELLAs restrict growth and development are largely unknown. This study reveals an important step of the mechanism. Previous microarray studies identified SCARECROW-LIKE 3 (SCL3) as a direct target gene of DELLA in Arabidopsis seedlings. SCL3 expression is induced by DELLA and repressed by GA. Unexpectedly, a scl3 null mutant displays reduced GA responses and elevated expression of GA biosynthesis genes during seed germination and seedling growth, indicating that SCL3 functions as a positive regulator of GA signaling. SCL3 seems to act as an attenuator of DELLA proteins. Transient expression, ChIP, and co-IP studies show that SCL3 autoregulates its own transcription by directly interacting with DELLA. Our data further show that SCL3 and DELLA antagonize each other in controlling both downstream GA responses and upstream GA biosynthetic genes. This work is beginning to shed light on how this complex regulatory network achieves GA homeostasis and controls GA-mediated growth and development in the plant.

    Original languageEnglish
    Pages (from-to)2160-2165
    Number of pages6
    JournalProceedings of the National Academy of Sciences of the United States of America
    Issue number5
    Publication statusPublished - 2011 Feb 1


    • DELLA attenuator
    • Gibberellin-regulated development
    • Hormone homeostasis
    • SCARECROW-LIKE 3-DELLA interaction

    ASJC Scopus subject areas

    • General


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