基于叶绿体全基因组序列变异位点的葫芦科植物资源遗传多样性的分子鉴定新方法
A Novel Method for Molecular Identification of Genetic Diversity of Plant Resources in Cucurbitaceae Based on Taxon-Specific Variable Nucleotide Characters from Complete Chloroplast Genomes

植物遗传多样性的精确鉴定是资源利用和相关产业发展的基础。我们利用来自葫芦科5个属(种和亚种)的叶绿体全基因组序列中的物种特有的4952个核苷酸变异位点作为分子性状编制分子鉴定检索表，供试样品得到成功鉴定。物种特有变异位点的数量和核苷酸构成存在属(种)间差异。马瓟瓜Cucumis melo subsp. agrestis (1753)和黑子南瓜Cucurbita ficifolia (1542)的特有变异位点的数量显著多于西瓜Citrullus lanatus (727)、藏瓜Indofevillea khasiana (623)和罗汉果Siraitia grosvenori (307)。罗汉果的特有变异位点的数量最少。马瓟瓜的特有变异位点中，T的比例(29.78%)均高于A、C或G (22.48%~24.30%)。黑子南瓜的特有变异位点中，A的比例(19.52%)低于T、C或G (24.97%~28.15%)。西瓜的特有变异位点中，A或T的比例(18.57%或21.46%)低于C或G (30.67%或29.30%)。藏瓜的特有变异位点中，T的比例(20.55%)低于A、C或G (25.04%~27.61%)。罗汉果的特有变异位点中，C的比例(21.82%)低于A、T或G (25.73%~26.71%)。结果显示，叶绿体基因组的单核苷酸变异位点信息，可用于葫芦科植物资源遗传多样性的分子鉴定。调查了中国过去120多年来葫芦科植物标本的收集现状，讨论了存在的问题与对策。本研究对于葫芦科植物种质资源的保护和利用以及相关产业的发展具有重要价值。
Accurate identification of genetic diversity is essential for utilization of plant resources and development of the related industries. In this paper, 4952 taxon-specific variable nucleotide characters in the complete chloroplast genome of 5 species/subspecies from 5 genera in the Cucurbitaceae were used as molecular traits to identify the genetic resources of this plant family and to compile a molecular classification key for the first time. There are differences in aspects of amount and base composition of variable nucleotide characters among the species. The amount of taxon-specific variable nucleotide characters in Cucumis melo subsp. agrestis (1753) or Cucurbita ficifolia (1542) are significantly larger than those of Citrullus lanatus (727), Indofevillea khasiana (623) or Siraitia grosvenori (307). Siraitia grosvenori is the lowest in the amount of taxon-specific variable nucleotide characters. The proportion of T (29.78%) is higher than that of A, C or G (22.48%~24.30%) in Cucumis melo subsp. agrestis. The proportion of A (19.52%) is lower than that of T, C or G (24.97%~28.15%) in Cucurbita ficifolia. The proportion of A or T (18.57% or 21.46%) is lower than that of C or G (30.67% or 29.30%) in Citrullus lanatus. The proportion of T (20.55%) is lower than that of A, C or G (25.04%~27.61%) in Indofevillea khasiana. The proportion of C (21.82%) is lower than that of A, T or G (18.57%~21.46%) in Siraitia grosvenori. Our results indicated that taxon-specific variable nucleotide characters from the chloroplast genomes could be used for discrimination of different genera or species/subspecies in the Cucurbitaceae. The status of Cucurbitaceae plant specimens collected in the past over 120 years in