ARID5-ISWI complex controls plant fertility by regulating male and female gametogenesis

Plant reproduction requires coordinated male and female reproductive organ development and coordinated gametes maturation. In this study, we characterize an ARID (AT-Rich Interacting Domain)-containing protein, ARID5, that shows strong interactions with subunits of AtISWI chromatin remodeling complex. arid5 and rlt1-1 rlt2-1 (RLT1, RLT2 are subunits of AtISWI complex) mutants exhibit similar pleiotropic phenotypes, and the defective plant fertility catches our eyes. To determine the cause of reduced reproduction by disruption of ARID5-ISWI, we firstly examined the flower organ development of the three mutants. Indeed, we observed that filament length is obviously shorter, anther size is much smaller and the pollen count is significantly fewer in arid5 and rlt1-1 rlt2-1 mutants compared to WT. Moreover, transcriptional analysis shows that genes involved in jasmonate biosynthesis are significantly de-regulated in stamens of arid5 and rlt1-1 rlt2-1 mutants. And exogenous JA treatment can rescue filament phenotype and partially rescue fertilities of arid5 and rlt1-1 rlt2-1 mutants. Considering that mutants hand-pollinated with their own pollen harbor around 80% seed sets, we verify that the remaining ~20% of aborted seeds are due to developmental defects in female gametophytes. Collectively, this study identifies a new function of ARID5-ISWI complex, which involves in regulating both male and female gametogenesis.