RAV1 Negatively Regulates Seed Development by Directly Repressing MINI3 and IKU2 in Arabidopsis

  • Shin, Hyun-young (Department of Biological Sciences, Sookmyung Women's University) ;
  • Nam, Kyoung Hee (Department of Biological Sciences, Sookmyung Women's University)
  • 투고 : 2018.06.18
  • 심사 : 2018.10.01
  • 발행 : 2018.12.31


A plant-specific B3 domain and AP2 domain-containing transcription factor, RAV1 acts as a negative regulator of growth in many plant species and its transcription was down-regulated by BR and ABA. In this study, we found that RAV1-overexpressing transgenic plants showed abnormally developed ovules, resulting in reduced seed size, weight, and number in a silique. Interestingly, the endogenous expression of RAV1 fluctuated during seed development; it remained low during the early stage of seed development and sharply increased in the seed maturation stage. In plants, seed development is a complex process that requires coordinated growth of the embryo, endosperm, and maternal integuments. Among many genes that are associated with endosperm proliferation and embryo development, three genes consisting of SHB1, MINI3, and IKU2 form a small unit positively regulating this process, and their expression was regulated by BR and ABA. Using the floral stage-specific RNAs, we found that the expression of MINI3 and IKU2, the two downstream genes of the SHB1-MINI3-IKU2 cascade in the seed development pathway, were particularly reduced in the RAV1-overexpressing transgenic plants. We further determined that RAV1 directly binds to the promoter of MINI3 and IKU2, resulting in their repression. Direct treatment with brassinolide (BL) improved seed development of RAV1-overexpressing plants, but treatment with ABA severely worsened it. Overall, these results suggest that RAV1 is an additional negative player in the early stages of seed development, during which ABA and BR signaling are coordinated.

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Fig. 1. Defective seed development in the RAV1- overexpressing transgenic plants.

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Fig. 2. Defective seed development continues to adversely affect seed germination.

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Fig. 3. Expression analyses of RAV1 during seed development.

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Fig. 4. Expression analyses of the genes associated with embryo and endosperm development.

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Fig. 5. RAV1 directly binds to the promoter of MIN3 and IKU2.

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Fig. 6. RAV1 interacts with BR and ABA signaling.


연구 과제 주관 기관 : Rural Development Administration, National Research Foundation of Korea (NRF)


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