水稻中的“伥鬼”:不同表观遗传状态的同一转基因之间的相互作用  

“Chang Ghost”in rice:the interactions between same transgenes with different epigenetic states

作　　者：殷雨萌 曾龙军 王莉莉 郑克志 徐大超 杨东雷 YIN Yumeng;ZENG Longjun;WANG Lili;ZHENG Kezhi;XU Dachao;YANG Donglei(State Key Laboratory of Crop Genetics and Germplasm Enhancement,Nanjing Agricultural University,Nanjing 210095,China;Plant Phenomics Research Center,Nanjing Agricultural University,Nanjing 210095,China)

机构地区：[1]南京农业大学作物遗传与种质创新国家重点实验室,南京210095 [2]南京农业大学作物表型组学交叉研究中心,南京210095

出　　处：《植物生理学报》2020年第9期1784-1794,共11页Plant Physiology Journal

基　　金：国家自然科学基金(31671340);国家重点研发计划(2016YFD0100603-9);江苏省自然科学基金(BK20170027);转基因专项(2016ZX08001002)。

摘　　要：位于同源染色体的一对等位基因通过减数分裂与受精独立地遗传给子代,在F1及随后的世代中等位基因独立地表达,这一过程中DNA序列是其表达调控与功能的决定因素。但是基因组印记、X染色体失活、副突变等生命现象并不符合孟德尔遗传定律。在本研究中,利用强启动子35S驱动赤霉素代谢酶编码基因OsGA2ox1,并遗传转化水稻,获得的OsGA2ox1ectopicexpression(GAE)转基因水稻表现出植株矮化、叶色深绿、开花延迟等赤霉素严重缺失的典型表型。在转基因植株的后代中出现了表型恢复、与野生型相同的植株。基因型鉴定发现它们含有35S::OsGA2ox1,但是OsGA2ox1的转录降低到与野生型相当的水平,因此将其命名为OsGA2ox1 silencing(GAS)。进一步研究发现,与矮化的GAE植株相比,GAS的35S启动子上DNA甲基化水平明显升高,表明基因沉默很可能发生在转录水平上。利用这些转基因沉默的GAS与OsGA2ox1超表达的GAE水稻进行正反杂交,所得到的F1代植株都未呈现出赤霉素缺失表型,并且它们35S启动子上的DNA甲基化水平与GAS一样高。在随后的F2、F3代群体中也未出现过矮化的植株。这表明在F1代植株中,GAS沉默的35S::OsGA2ox1与GAE超表达的35S::OsGA2ox1之间发生了相互作用,改变了超表达的35S::OsGA2ox1表观遗传学状态,而且改变后的35S::OsGA2ox1的表观遗传学状态可以稳定地遗传给后代。本研究的发现将为转基因聚合育种提供重要的理论指导。A pair of alleles on the homologous chromosome independently passes on in offspring through meiosis and fertilization.In F1 and subsequent generations,the alleles are independently expressed.The DNA sequence of gene determines its function and expression pattern.However,in the biological processes such as genomic imprinting,X-chromosome inactivation and paramutation,alleles do not comply the genetic laws.In this study,the constitutive promoter,35 S was used to drive the gibberellin metabolism gene,OsGA2 ox1.OsGA2 ox1 ectopic expression(GAE)transgenic rice exhibited a series of gibberellin deficient phenotypes such as plant dwarfism,dark green leaves,and delayed flowering.In the progeny of the GAE,a rice plant restored the development defects of GA deficiency.Genotyping confirmed the existence of 35 S::OsGA2 ox1,however,the transcriptional level of Os GA2 ox1 was reduced to a level comparable to that of the WT.We therefor named it as OsGA2 ox1 silencing(GAS).Bisulfite sequencing demonstrated that DNA methylation level on the 35 S promoter in GAS was increased than that in GAE,suggesting that gene silencing likely occur at the transcription level.The F1 plants from crossing GAS with GAE did not exhibit gibberellin-deficient phenotype,suggesting that overexpressed 35 S::Os GA2 ox1 from GAE was silenced.Furthermore,the DNA methylation was increased on 35 S promoter in F1 plants,suggesting that silenced 35 S::OsGA2 ox1 of GAS inactivated overexpressed 35 S::OsGA2 ox1 of GAE through DNA methylation.In subsequent generations(F2 and F3),the GA-deficient plant did not segregate out,suggesting that inactivated overexpressed 35 S::OsGA2 ox1 of GAE could be inherited.This study provides new insights in the behaviors of transgenes.

关 键 词：水稻 副突变 OsGA2ox1 赤霉素 基因沉默 

分 类 号：S511[农业科学—作物学]