Clearance of maternal barriers by paternal miR159 to initiate endosperm nuclear division in Arabidopsis

【摘要】：Sperm entry triggers central cell division during seed development,but what factors besides the genome are inherited from sperm,and the mechanism by which paternal factors regulate early division events,are not understood.Here,We showed that spermtransmitted miR159 promotes endosperm nuclear divisionthrough repressing the central cell-transmitted miR159 targets.Disruption of both maternal and paternal miR159 caused approximately half seeds abortion,and loss of paternal miR159 specifically resulted in arrested and/or delayed endosperm nuclear divisions in substantial portion of seeds.In wild type plants,MYB33 and MYB65,two miR159 targets,were highly expressed in the central cell before fertilization,but both of them were rapidly abolished after fertilization.In contrast,loss of paternal miR159 led to retention of MYB33 and MYB65 in the central cell after fertilization.Furthermore,ectopic expression of miR159-resistant version of MYB33(mMYB33)in the endosperm significantly inhibited the initiation of endosperm nuclear division.Collectively,these results show that paternal miR159 inhibits its maternal targets to promote endosperm nuclear division,thus uncovering a previously unknown paternal effect on seed development.