The Application Of Repeated Sequence Itf₁ And Itf₂ In Analysis Of Ipomoea Karyotype And The ITS Sequence Identification Of Ipomoea Batatas And Its Wild Relatives

In this study, we selected I. trifida, which has been published as the closest specie to the I. batatas ancestral species, to detecte its repeated sequences by sequencing and FISH for standardizing the karyotype of I. trifida（2x）, I. trifida（2x） and I. batatas ′Xushu18′. Moreover, we selected ten pieces of I. batatas relative wild species, using r DNA ITS sequencing analysis to identify the genetic relationship between I. batatas ′Xushu18′ and its relative wild species. The results show that:1. We detected two representative repeats, which named as Itf₁ and Itf₂, by analysis of combination and hybridization. The signals of two repeats in diploid I. trifida are 16 and 8, four of them located in the same chromosomes. Compare with 45 s, there are two signals of Itf₁ located in the same chromosomes. The same as Itf₂ and 5S.2. Itf₁, 45 S and 5S signals in both I. trifida（6x） and I. batatas ′Xushu18′ are 3 time than in I. trifida（2x）, while the location of Itf₂ in both I. trifida（6x） and I. batatas ′Xushu18′, which have 2 pair of signals non-overlapped with Itf₁, are different from in the diploid of I. trifida, which have 4 pair of signal.3. The hybrid of repeat sequences and r DNA turned to a standard model picture of I. trifida（2x）. The consequence of the analysis of I. trifida（2x）, I. trifida（6x）and I. batatas ′Xushu18′ showed the closer relationship.4. The analyzed nr DNA ITS sequences range from 570 bp to 600bp: the ITS1 fragments were from 185 bp to 209 bp, with GC content of 53.11%-61.83%; the ITS2 regions were 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%; The informative sites lie in ITS1 and ITS2 sequences;5. The phylogenetic analysis revealed that I. batatas ′Xushu18′ has a more close phylogenetic relationship 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 Jacq., and I. purpurea. Moreover, the interspecific hybrid and the backcross line have more close phylogenetic relationships with I. batatas ′Xushu18′, when comparing to I. hederacea Jacq.;...