엽록체 trnL-trnF intergenic spacers (IGS) 영역과 핵 리보솜 Internal Transcribed Spacer (ITS) 영역 염기서열을 이용한 제주도 내 ‘인창귤’(‘Inchangkyool’)과 중국 의창 지(Citrus ichangensis ‘Ichangensis’) 품종과의 유전학적 분석

Comparative Genetic Analysis between the Jeju ‘Inchangkyool’ and Chinese ‘Ichangensis’ (Citrus ichangensis) using Internal Chloroplast trnL-trnF Intergenic Spacers and Transcribed Spacer Sequence Regions

‘Inchangkyool’ varieties, which are believed to have been cultivated in Jeju for a long time, have leaves and flowers with a lemon-likefragrance. They have been suggested to be given the same scientific name as Citrus ichangensis, which is known to originate from China’sSouthwest and Midwest regions. However, the genetic characterization of ‘Inchangkyool’ has not been reported, and literature is not readilyavailable. Hence, in this study, 30 citrus chloroplast (cp)DNA (trnL-trnF) regions and nuclear ribosomal DNA internal transcribed spacer (ITS)regions were tested to identify the genetic relationship between ‘Inchangkyool’ and C. ichangensis and the origin of ‘Inchangkyool’ cultivars. Our results indicated that the total nucleotide sequence length of the trnL-trnF intergenic spacer (IGS) region and the G + C content was373 bp and 36.73%, respectively, in the cpDNA of C. ichangensis and ‘Inchangkyool’, whereas the ITS1 regions were 247 and 248 bp andthe ITS2 regions were 228 and 226 bp, respectively. Furthermore, the sequence lengths of the total ITS (ITS1 + 5.8S rDNA + ITS2) regionswere 638 and 637 bp, respectively, whereas the G+C content was 70.16%, 71.26%, 69.03%, 70.61%, 64.6%, and 65.49%, respectively - showingdifferences in the nuclear ribosomal DNA region. However, the nucleotide sequence length of the 5.8S rDNA region was 163 bp and theG + C content was 54.6%, which were the same for both varieties. In addition, sequence divergence and phylogenetic analysis of the trnL-trnFand ITS regions in chloroplast DNA showed that the sequence divergence of the trnL-trnF region on the chloroplast was 0-0.008. This resultindicates that ‘Inchangkyool’ is most closely related to Jeju eight native citrus cultivars including ‘Dongjeongkyool’. It is also closely relatedto C. ichangensis cultivars and six common citrus cultivars. In other words, the ‘Inchangkyool’ cultivar was inherited from the same maternalline as the Chinese C. ichangensis. The divergence values of the nuclear ribosomal DNA region between ‘Inchangkyool’ and ‘Dongjeongkyool’and C. ichangensis were 0.008 and 0.026, respectively. These results indicated that ‘Inchangkyool’ was most closely related to ‘Dongjeongkyool’,and was farther from the C. ichangensis cultivar. In addition, phylogenetic relationships found ‘Inchangkyool’ to belong to the same groupas the ‘Dongjeongkyool’ cultivar of jeju native citrus cultivars and a different group from C. ichangensis. From the above results, it is suggestedthat ‘Inchangkyool’ cultivar has been classified from the same maternal cultivar as the C. ichangensis in China, but has been obtained throughlong-term crossing with the same species as ‘Dongjeongkyool’. Moreover, based on the above results, it is believed that a distinct cultivarname for ‘Inchangkyool’ can be presented.