| Structural highlights
Function
[LEC2_ARATH] Transcription regulator that plays a central role in embryo development. Required for the maintenance of suspensor morphology, specification of cotyledon identity, progression through the maturation phase and suppression of premature germination. Ectopic expression is sufficient to promote somatic embryogenesis.[1] [2] [3]
Publication Abstract from PubMed
Some overwintering plants acquire competence to flower, after experiencing prolonged cold in winter, through a process termed vernalization. In the crucifer plant Arabidopsis thaliana, prolonged cold induces chromatin-mediated silencing of the potent floral repressor FLOWERING LOCUS C (FLC) by Polycomb proteins. This vernalized state is epigenetically maintained or 'memorized' in warm rendering plants competent to flower in spring, but is reset in the next generation. Here, we show that in early embryogenesis, two homologous B3 domain transcription factors LEAFY COTYLEDON 2 (LEC2) and FUSCA3 (FUS3) compete against two repressive B3-containing epigenome readers and Polycomb partners known as VAL1 and VAL2 for the cis-regulatory cold memory element (CME) of FLC to disrupt Polycomb silencing. Consistently, crystal structures of B3-CME complexes show that B3FUS3, B3LEC2 and B3VAL1 employ a nearly identical binding interface for CME. We further found that LEC2 and FUS3 recruit the scaffold protein FRIGIDA in association with active chromatin modifiers to establish an active chromatin state at FLC, which results in resetting of the silenced FLC to active and erasing the epigenetic parental memory of winter cold in early embryos. Following embryo development, LEC2 and FUS3 are developmentally silenced throughout post-embryonic stages, enabling VALs to bind to the CME again at seedling stages at which plants experience winter cold. Our findings illustrate how overwintering crucifer annuals or biennials in temperate climates employ a subfamily of B3 domain proteins to switch on, off and on again the expression of a key flowering gene in the embryo-to-plant-to-embryo cycle, and thus to synchronize growth and development with seasonal temperature changes in their life cycles.
Embryonic resetting of the parental vernalized state by two B3 domain transcription factors in Arabidopsis.,Tao Z, Hu H, Luo X, Jia B, Du J, He Y Nat Plants. 2019 Apr;5(4):424-435. doi: 10.1038/s41477-019-0402-3. Epub 2019 Apr , 8. PMID:30962525[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Stone SL, Kwong LW, Yee KM, Pelletier J, Lepiniec L, Fischer RL, Goldberg RB, Harada JJ. LEAFY COTYLEDON2 encodes a B3 domain transcription factor that induces embryo development. Proc Natl Acad Sci U S A. 2001 Sep 25;98(20):11806-11. doi:, 10.1073/pnas.201413498. PMID:11573014 doi:http://dx.doi.org/10.1073/pnas.201413498
- ↑ Braybrook SA, Stone SL, Park S, Bui AQ, Le BH, Fischer RL, Goldberg RB, Harada JJ. Genes directly regulated by LEAFY COTYLEDON2 provide insight into the control of embryo maturation and somatic embryogenesis. Proc Natl Acad Sci U S A. 2006 Feb 28;103(9):3468-73. doi:, 10.1073/pnas.0511331103. Epub 2006 Feb 21. PMID:16492731 doi:http://dx.doi.org/10.1073/pnas.0511331103
- ↑ Stone SL, Braybrook SA, Paula SL, Kwong LW, Meuser J, Pelletier J, Hsieh TF, Fischer RL, Goldberg RB, Harada JJ. Arabidopsis LEAFY COTYLEDON2 induces maturation traits and auxin activity: Implications for somatic embryogenesis. Proc Natl Acad Sci U S A. 2008 Feb 26;105(8):3151-6. doi:, 10.1073/pnas.0712364105. Epub 2008 Feb 19. PMID:18287041 doi:http://dx.doi.org/10.1073/pnas.0712364105
- ↑ Tao Z, Hu H, Luo X, Jia B, Du J, He Y. Embryonic resetting of the parental vernalized state by two B3 domain transcription factors in Arabidopsis. Nat Plants. 2019 Apr;5(4):424-435. doi: 10.1038/s41477-019-0402-3. Epub 2019 Apr , 8. PMID:30962525 doi:http://dx.doi.org/10.1038/s41477-019-0402-3
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