Analysis of Genetic Characteristic of Jujube (Ziziphus jujuba Mill.) Cultivated in Korea Revealed by ISSR Markers

ISSR 표지를 이용한 국내 재배 대추나무의 유전특성 분석

Abstract

Chinese jujube (Ziziphus jujuba Mill.), a member of family Rhamnaceae, is an economically important species. It has high nutritional value in fruits, and its medicinal properties have led to extensive use in traditional oriental medicine. In this study, we investigated the genetic characteristics of 270 jujube germplasms collected from the six major jujube fruit production areas in Korea including Boeun and Gyeongsan, in order to understand the current situation on cultivated varieties of domestic jujube and to obtain useful data for selection of superior germplasms and establishing their breeding plans. The results of ISSR marker analysis revealed that the Shannon's information index of the 270 germplasms was 0.107 and the genetic similarity was as high as 0.935 showing the dominance of a specific cultivar or germplasm, and almost 67% (180) of them were identified at the same genotype with 'Bokjo'. The domestic commercial jujube populations could be characterized by very low genetic diversity and thus may be vulnerable to external disturbances. In addition, it seems that most of the jujube fruits in domestic market were largely produced through parthenocarpy.

대추나무는 갈매나무과에 속하며 과실에 높은 영양가를 지니고 있어 전통 한의학에서 널리 사용되고 있는 경제적으로 중요한 종이다. 국내에서 재배되고 있는 대추나무들의 품종실태를 파악함으로서 우량개체 선발과 육종계획 수립에 유용한 유전정보를 얻고자 보은, 경산 등 대추 주산지 6곳에서 수집된 대추나무 270개체를 대상으로 ISSR 표지 분석을 수행하였다. 그 결과 유전적 다양성을 보여주는 S.I.값은 0.107, 유전적 유사도는 0.935로 높게 나타나 연구에 사용된 대추나무들이 특정 품종 또는 개체에 편중되어 있었다. 또한 270개체 중 67%인 180개체가 '복조'와 동일한 유전자형을 나타내는 것으로 관찰되었다. 본 연구를 통해 국내 재배 대추나무 개체들의 유전적 다양성이 매우 낮은 것으로 파악되었다. 이에 외부 교란에 취약할 가능성이 큰 것으로 예상되며, 시장에 판매되고 있는 대부분의 대추가 단위결실을 통해 생산되는 것으로 판단된다.

Figure 1. Map showing the major jujube producing cities in Korea where jujube samples were collected. Cities are marked with a red circle and numbered from 1 to 6.

Figure 2. Dendrogram generated by UPGMA cluster analysis from thirty one jujube genotypes and six jujube cultivars. Genotype D and W were identified as the major cultivated cultivar ‘Bokjo’ and local cultivar ‘Boeundaechu’. The numbers in parenthesis indicate how many individuals are in each genotype.

Table 1. Sample location and sample size of jujube germplasm examined in the ISSR analysis. Six jujube sample collecting locations are the major jujube producing cities in Korea.

Table 2. ISSR primers used in this study and summary of ISSR markers from 270 cultivated jujube samples.

Table 3. Identified genotypes, their number and ‘Bokjo’ cultivar frequency in the six jujube sample collecting locations.

Table 4. Summary of genetic variation statistics for all loci in 270 cultivated jujube samples.