Ancestral function but divergent epigenetic regulation of HAIKU2 reveals routes of seed developmental evolution  

作　　者：Di Wu Yiming Wei Xiangyu Zhao Boka Li Huankai Zhang Gang Xu Juntong Lv Dajian Zhang Xiansheng Zhang Min Ni 

机构地区：[1]National Key Laboratory of Crop Biology,College of Life Sciences,Shandong Agricultural University,Taian 271018,China [2]State Key Laboratory of Systematic and Evolutionary Botany,CAS Center for Excellence in Molecular Plant Sciences,Institute of Botany,Chinese Academy of Sciences,Beijing100093,China [3]University of Chinese Academy of Sciences,Beijing 100049,China [4]Department of Plant and Microbial Biology,University of Minnesota at Twin Cities,Saint Paul,MN 55108,USA

出　　处：《Molecular Plant》2022年第10期1575-1589,共15页分子植物（英文版）

基　　金：the National Natural Science Foundation of China(32071921 X.YZJ);National Key Research and Development Program 2021YFF1001203(D.J.Z);National Natural Science Foundation of China 31730008(X.S.Z.);National Science Foundation IOS-1933291(M.N.).

摘　　要：Evolution is driven by various mechanisms.A directional increase in the embryo to endosperm ratio is an evolutionary trend within the angiosperms.The endosperm constitutes a major portion of the seed volume in Poales and some dicots.However,in other dicots such as Arabidopsis and soybean,the endosperm proliferates early,followed by embryo growth to replace the endosperm.The Arabidopsis leucine-rich repeat receptor protein kinase AtHAIKU2(AtIKU2)is a key regulator of early endosperm proliferation.In this study,we found that IKU2s from Brachypodium,rice,and soybean can complement the abnormal seed developmental phenotype of Atiku2,while AtIKU2 also rescues the defective endosperm proliferation in the Brachypodium BdIKU2 knockout mutant seeds.AtIKU2 and soybean GmIKU2 are actively expressed a few days after fertilization.Thereafter,expression of AtIKU2 is suppressed by the FIS-PRC2 complex-mediated H3K27me3.The soybean GmIKU2 locus is also enriched with H3K27me3 marks.The histone methyltransferase AtMEA is unique to Brassicaceae,but one GmSWN in soybean plays a similar role in seed development as AtMEA.By contrast,the BdIKU2 and rice OsIKU2 loci are continuously expressed and are devoid of H3K27me3 marks.Taken together,these results suggest that IKU2 genes retain an ancestral function,but the duration of their expression that is controlled by PRC2-mediated epigenetic silencing contributes to silenced or persistent endosperm proliferation in different species.Our study reveals an epigenetic mechanism that drives the development of vastly different seed ontogenies.

关 键 词：BRASSICALES ENDOSPERM Fabales IKU2 MEDEA POALES 

分 类 号：Q943.2[生物学—植物学]