高黎贡山旱冬瓜Frankia的IGS PCR-RFLP分析

在云南省高黎贡山自然保护区海拔1310～2400m的范围内，采集30个旱冬瓜根瘤样品，直接从根瘤中提取Frankia DNA，对其，nifD-nifK基因间隔区(intergenic spacer，IGS)和16S-23S rDNA IGS进行PCR—RFLP分析．结果表明，nifD-nifK IGS的PCR产物长度差异很大，经HaeⅢ和Afa I双酶切后，得到15种酶切带型，检测到多种基因型的菌株同时与同一株宿主植物共生；16S-23S rDNA IGS的PCR产物长度相似，酶切后亦区分出15种酶切带型．通过对两个基因间隔区的PCR-RFLP联合分析，发现高黎贡山旱冬瓜Frankia存在20种基因型．

Diversity of Frankia in nodules of Alnus nepalensis at Gaoligong mountains revealed by IGS PCR-RFLP analy-sis

30 nodule samples were used to assess the diversity of Frankia strains symbiotically associated with Alnus nepalensis naturally occurring at the Gaoligong Mountains in Yunnan Province, China. DNA was extracted directly from nodules, and its two target DNA regions that encode nifD-nifK intergenic spacer (IGS) and 16S-23S rDNA IGS was studied by PCR-RFLP. The PCR fragments yielded by the nifD-nifK IGS were noticeably different in size, and when they were digested by Hae III and Afa I, 15 nif-type Frankia strains could be detected, the PCR-RFLP result of this region also could show that more than one genotype Frankia strains could form symbiosis with individual plants at the same time. The 16S-23S rDNA IGS had similar PCR fragments, but still identified 15 rrn-type strains after digested by Hae III and Afa I. 20 genotype strains could be found only when combined the PCR-RFLPs of two target regions.