A plant-specific ISWI subunit is involved in fertility by inhibiting the pistil overgrowth

we identified the forkhead-associated domain 2 (FHA2) as a plant-specific subunit of an ISWI chromatin-remodeling complex in Arabidopsis. By in vivo and in vitro analyses, we demonstrated that FHA2 directly binds to RLT1 and RLT2, two redundant subunits of the ISWI complex in Arabidopsis. A reduced-fertility phenotype was observed in both the fha2 and rlt1/2 mutant plants and the phenotype was ascribed to overgrowth of the pistil during the floral development. However, the early-flowering phenotype of the rlt1/2 mutant was not shared by the fha2 mutant. Consistently, our RNA-seq analysis indicated that the fha2 mutant affects a subset of rlt1/2-regulated genes but not genes involved in the regulation of flowering time. This study demonstrates that FHA2 functions as a previously uncharacterized subunit of the Arabidopsis ISWI complex to exclusively regulate the pistil growth during the floral development. Examination of the mRNA expression in Arabidopsis