栽培种甘薯及其近缘野生种nrDNA ITS序列分析

Analysis of nrDNA ITS Sequences in Ipomoea batatas and its Relative Wild Species

采用核糖体DNA内转录间隔区（nrDNAITS）序列比较分析了甘薯及其近缘野生种的遗传多样性及系统进化关系，首次报道了栽培种甘薯‘徐薯18’（Ipomoea batatas‘Xushu 18’）及其近缘野生种I．triloba（DOM），I．cordatotriloba（MEX），I．nil（PER）。I．nil（JPN）。I．hederacea Jacq．（USA），f．hederacea Jacq．（HK）和种间杂交种67-1（I．batatas‘Xushu18’×I．hederacea Jacq．）及回交种（67-1×I．batatas‘Xushu18’）的nrDNAITS序列。序列分析表明，栽培种甘薯及其近缘野生种nrDNAITS序列长度为570-600bp。其中，ITS1序列为185～209bp，GC含量为53．11％～61．83％；ITS2序列为214-226bp，GC含量为61．21％-72．89％；5．8S序列均为165bp，GC含量为54．55％-55．76％。此外，栽培种甘薯及其近缘野生种ITS序列信息位点均集中在ITS1和ITS2区；与其他甘薯属植物相比，I．wrightii ITS2的末端缺失了6～8个碱基。系统进化分析表明，栽培种甘薯‘徐薯18’（I．batatas‘Xushu18’）和野生种I．triloba、I．cordatotriloba、I．ecunosa、I．trifida的亲缘关系较近，与I．wrightii、I．pes-tigridis、I．grandifolia、I．nil、I．hederaceaJacq．、I．pur-purea的亲缘关系较远；杂交后代与栽培种甘薯‘徐薯18’（I．batatas‘Xushu18’）亲缘关系较近，与野生种父本I．hederaceaJacq．的亲缘关系较远。

In this study, the internal transcribed spacer of nucleus ribosome DNA （ nrDNA ITS） copies from Ipomoea batatas and its wild relatives were cloned and sequenced to analyze their phylogenetic relationships. For the first time, we report on the nrDNA ITS sequences isolated from I. batatas ＇Xushu18＇ and its relative wild species （I. triloba （DOM）, I. cordatotriloba （MEX）, I. nil（PER）, I. nil（JPN）, I. hederacea Jacq. （USA）, I. hederacea Jacq. （HK））, an interspecific hybrid 67-1 （ I. batatas ＇ Xushu18＇ x I. hederacea Jacq.）, and a backcrossline （67-1 × I. batatas ＇ Xushu18＇ ）. Analysis showed that the nrDNA ITS sequences ranged from 570 bp to 600 bp. Among them, the ITS1 fragments ranged from 185 bp to 209 bp, with GC content of 53.11%-61.83%; the ITS2 regions ranged from 214 bp to 226 bp, with GC content of 61.21%-72.89%; the 5.8S sequences were 165 bp, with GC content of 54.55%- 55.76%. Furthermore, the informative sites of I. batatas and its wild relatives lay in the ITS1 and ITS2 regions; in contrast to other Ipomoea germplasms, there was a 6-8 bp deletion in the ITS2 of I. wrightii. Phylogenetic analysis revealed that I. batatas ＇Xushu18＇ had closer phylogenetic relationships with the wild relatives of I. triloba, I. cordatotriloba, I. lacunosa, and I. trifida than I. wrightii, I. pes-tigridis, I. grandifolia, I. nil, I. hederacea, and I. purpurea. Moreover, the interspecific hybrid and the backcross line had closer phylogenetic relationships with I. batatas ＇Xushu18＇, compared to I. hederacea.