Remarkable variation of ribosomal（rDNA） DNA in gnetophytes, a distinct lineage of gymnosperms
作者单位：Institute of Clinical PharmacologyGuangzhou University of Chinese Medicine School of Biological and Chemical SciencesQueen Mary University of London Key Laboratory of Southern Subtropical Plant DiversityFairy Lake Botanical GardenShenzhen & Chinese Academy of Science Sino-Africa Joint Research CenterChinese Academy of Science Institute of BiophysicsAcademy of Sciences of the Czech Republic Jodrell LaboratoryRoyal Botanic Gardens
会议名称：《中国植物学会第十六次全国会员代表大会暨85周年学术年会》
会议日期：2018年
学科分类：0710[理学-生物学] 07[理学] 09[农学] 071007[理学-遗传学] 0901[农学-作物学] 090102[农学-作物遗传育种]
关 键 词：gnetophytes rDNA organization chromosome evolution high through-put sequencing concerted evolution pseudogenes intragenomic diversity
摘 要：Gnetophytes,comprising genera Ephedra,Gnetum and Welwitschia are an understudied,enigmatic lineage of *** we examined the organization of ribosomal DNA（rDNA） across representative *** applied high throughput sequencing approaches to isolate and reconstruct rDNA units and to determine their intragenomic *** addition,fluorescent in situ hybridization（FISH） and Southern blot hybridization techniques were used to reveal the chromosome and genomic organization of *** found that:（i） the 5 S and 35 S rDNAs were separate in ***,*** and *** and linked in ***;（ii） there was huge variability variability in 5 S rDNA abundance（4,000-100,000 copies per haploid genome） and locus numbers（2-16 sites per diploid genome）;（iii） 5 S rRNA pseudogenes were interspersed between functional genes forming single unit in *** and ***;（iv） in *** internal transcribed spacers（ITS1） of 35 S rDNA were long and intrinsically repetitive while in *** and *** the ITS1 were short without *** conclusion,gnetophytes are distinctive from other gymnosperms and angiosperms as they display a surprisingly high variability in rDNA organization,rDNA copy and locus numbers between genera,with no relationship between copy numbers and genome sizes *** evolution of 5 S rDNA units seems to have led to the amplification of 5 S pseudogenes in both *** and *** patterns of rDNA show both gymnosperm and angiosperm features underlining diversity and distinctness of the group.