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SUMMARY Switch defective/sucrose non‐fermentable (SWI/SNF) chromatin remodeling complexes are evolutionarily conserved, multi‐subunit machinery that play vital roles in the regulation of gene expression by controlling nucleosome positioning and occupancy. However, little is known about the subunit composition of SPLAYED (SYD)‐containing SWI/SNF complexes in plants. Here, we show that theArabidopsis thalianaLeaf and Flower Related (LFR) is a subunit of SYD‐containing SWI/SNF complexes. LFR interacts directly with multiple SWI/SNF subunits, including the catalytic ATPase subunit SYD,in vitroandin vivo. Phenotypic analyses oflfr‐2mutant flowers revealed that LFR is important for proper filament and pistil development, resembling the function of SYD. Transcriptome profiling revealed that LFR and SYD shared a subset of co‐regulated genes. We further demonstrate that the LFR and SYD interdependently activate the transcription ofAGAMOUS(AG), a C‐class floral organ identity gene, by regulating the occupation of nucleosome, chromatin loop, histone modification, and Pol II enrichment on theAGlocus. Furthermore, the chromosome conformation capture (3C) assay revealed that the gene loop atAGlocus is negatively correlated with theAGexpression level, and LFR‐SYD was functional to demolish theAGchromatin loop to promote its transcription. Collectively, these results provide insight into the molecular mechanism of the Arabidopsis SYD‐SWI/SNF complex in the control of higher chromatin conformation of the floral identity gene essential to plant reproductive organ development.
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The MIO1‐MtKIX8 module regulates the organ size in Medicago truncatula
Abstract Plant organ size is an important agronomic trait tightly related to crop yield. However, the molecular mechanisms underlying organ size regulation remain largely unexplored in legumes. We previously characterized a key regulator F‐box protein MINI ORGAN1 (MIO1)/SMALL LEAF AND BUSHY1 (SLB1), which controls plant organ size in the model legumeMedicago truncatula. In order to further dissect the molecular mechanism, MIO1 was used as the bait to screen its interacting proteins from a yeast library. Subsequently, a KIX protein, designated MtKIX8, was identified from the candidate list. The interaction between MIO1 and MtKIX8 was confirmed further by Y2H, BiFC, split‐luciferase complementation and pull‐down assays. Phylogenetic analyses indicated that MtKIX8 is highly homologous toArabidopsisKIX8, which negatively regulates organ size. Moreover, loss‐of‐function ofMtKIX8led to enlarged leaves and seeds, while ectopic expression ofMtKIX8inArabidopsisresulted in decreased cotyledon area and seed weight. Quantitative reverse‐transcription PCR and in situ hybridization showed thatMtKIX8is expressed in most developing organs. We also found that MtKIX8 serves as a crucial molecular adaptor, facilitating interactions with BIG SEEDS1 (BS1) and MtTOPLESS (MtTPL) proteins inM. truncatula. Overall, our results suggest that the MIO1‐MtKIX8 module plays a significant and conserved role in the regulation of plant organ size. This module could be a good target for molecular breeding in legume crops and forages.
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- Award ID(s):
- 2233714
- PAR ID:
- 10507438
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Physiologia Plantarum
- Volume:
- 175
- Issue:
- 5
- ISSN:
- 0031-9317
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1111/ppl.14046
