‘冬枣’天然二、四混倍体的发现与评价

Discovery and Evaluation of Natural Mixoploid (2x + 4x) Variants in Ziziphus jujuba Mill.‘Dongzao'

以山东省沾化县栽培的普通‘冬枣’及其3个大果型变异类型‘沾冬2号’、变异1号、变异2号为试材,对其染色体倍性、DNA指纹、果实和叶片形态及果实主要营养指标进行了比较分析。经流式细胞仪测定,3个大果型变异类型均为二、四混倍体(2x+4x),其对照(母株)均为纯二倍体。经74对SSR引物检测,未发现3个大果型混倍体变异与其二倍体对照的DNA指纹存在差异,表明三者均确系来源于普通的二倍体‘冬枣’,其四倍体部分均属于同源加倍。与普通‘冬枣’相比,3个变异类型均表现出叶片变宽,叶形指数变小,果实变大,果形指数变小,果实维生素C含量增加,但果实可溶性糖和可滴定酸含量变化无规律。与已通过良种审定的‘沾冬2号’相比,新发现的变异1号和变异2号的单果质量更大,分别增大22.95%和15.90%,分别达到27.05 g和25.50 g。

Comparisons of chromosome ploidy,DNA fingerprint,fruit and leaf morphology,and fruit nutrition index were carried out among the common‘Dongzao＇cultivated in Zhanhua County,Shandong,and three bigger-fruit variants,i.e.‘Zhandong 2＇,variant No.1 and No.2. The results showed that the three bigger-fruit variants were all mixoploids（2x ＋ 4x）according to flow cytometry analysis,and their mother plants were pure diploids. No differences of DNA fingerprint were observed using 74 pairs of SSR primers between the three bigger-fruit variants and their diploid controls（common‘Dongzao＇）,indicating that they were really originated from the common diploid‘Dongzao＇and their 4x parts were autotetraploids. Compared to their diploid controls（common‘Dongzao＇）,the three mixploid variants had bigger and broader fruits with smaller fruit shape index,wider leaves with smaller leaf shape index,and significant higher content of vitamin C in fruit. However,the soluble sugar and titrable acid contents in fruits did not always change in accordance with the variations of ploidy. Compared to‘Zhandong 2＇having been released as a new excellent cultivar,the average fruit weight of variant No.1 and No.2 increased by 22.95% and 15.90% and reached 27.05 g and 25.50 g,repectively.