A plant-specific ISWI subunit is involved in fertility by inhibiting the pistil overgrowth. 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. Overall design: Examination of the mRNA expression in Arabidopsis

本研究鉴定得到叉头相关结构域2（forkhead-associated domain 2，FHA2）为拟南芥中ISWI染色质重塑复合物的植物特异性亚基。通过体内与体外实验分析，本研究证实FHA2可直接结合拟南芥ISWI复合物的两个功能冗余亚基RLT1与RLT2。fha2突变体与rlt1/2双突变体植株均表现出育性降低的表型，该表型归因于花发育过程中雌蕊的过度生长。但rlt1/2双突变体所具有的早花表型，并未在fha2突变体中出现。与之相符的是，本研究的RNA测序（RNA-seq）分析结果显示，fha2突变体仅影响rlt1/2调控基因中的一部分，而非参与开花时间调控的基因。本研究表明，FHA2作为拟南芥ISWI复合物中此前未被表征的亚基，可特异性调控花发育过程中的雌蕊生长。实验整体设计：对拟南芥的mRNA表达水平进行检测。