濒危植物邢氏水蕨和海南岛水蕨叶绿体序列rbcL比较及隐种分析

Comparison of Chloroplast SequencesrbcL of the Endangered Ceratopterisshingiiand C.thalictroides from Hainan Island in China,and Analysis of Cryptic Speciesof C.thalictroides

2021年,水蕨属(Ceratopteris)所有植物包括邢氏水蕨(C.shingii)、水蕨(C.thalictroides)和粗梗水蕨(C.pteridoides)被列为国家二级重点保护野生植物。水蕨属植物是研究植物性别决定、配子体形态建成以及遗传学、细胞生物学和生物化学等学科的模式植物之一,也是中国重要的野生水生植物种质资源。隐种(Cryptic species)问题已经成为系统分类研究、物种形成机制、生物进化和基于保护目的的种群遗传研究及保护计划共同关注的重要问题。基于叶绿体rbcL序列评价邢氏水蕨和海南岛陵水黎族自治县白水岭(BSL)、陵水黎族自治县木号镇(BJC)、海口城西镇(SPSK)等3个新发现的水蕨种群叶绿体序列rbcL的差异及系统发育关系,分析新发现尚未被评价的3个水蕨种群的隐种类型,为水蕨属不同物种和隐种的保护及利用提供科学依据。结果表明,邢氏水蕨和3个种群水蕨的rbcL序列长度为1227 bp,邢氏水蕨有2个变异位点,分别在783 bp处和1164 bp处。采用邻近法(NJ)构建了水蕨属叶绿体rbcL系统发育树。系统发育树显示BSL、BJC、SPSK等3个种群的水蕨与南方型水蕨隐种聚为同一支,表明这3个地方的水蕨隐种为南方型;而邢氏水蕨单独成一支。遗传距离分析显示BSL、BJC、SPSK种间遗传距离为0,与南方型水蕨之间遗传距离也为0;邢氏水蕨与BSL、BJC、SPSK遗传距离为0.002。结果进一步表明,海南岛的BSL、BJC、SPSK等3个种群水蕨为南方型水蕨,同时为邢氏水蕨的分类提供了佐证。不同的水蕨及隐种应该采取不同的保护策略,且邢氏水蕨应得到优先保护。保护邢氏水蕨和3个南方型水蕨种群的原生境是最有效的保护策略。

In 2021,all plants of the Ceratopteris genus,including C.shingii,C.thalichroides and C.pteridoides,were classified as endangered and listed in the second category of the Key Protected Wild Plants in China.Ceratopterisplants serve as model organisms for studying plant sex determination,gametophyte morphogenesis,genetics,cell biology,and biochemistry.Additionally,they represent vital aquatic plant germplasm resources in China.The issue of cryptic species has drawn significant attention in systematic classification research that explores species formation mechanisms,biological evolution,population genetics concerning conservation and conservation planning.This study compares the chloroplast rbcLsequence difference andphylogenetic relationshipof the endangered C.shingiiand C.thalictroides,distributed in Baishuling(BSL),Muhao town(BJC)ofLingshui Li Autonomous Countyand Chengxi town(SPSK)of Haikou city,Hainan Island,China.The cryptic species of C.thalictroideswas also evaluated.Results showed that therbcL sequence length of C.shingii and the three C.thalictroides populations were 1227 bp,with two mutation sites at 783 bp and 1164 bp in C.shingii.The chloroplast rbcL phylogenetic tree,constructed using the neighborjoining(NJ)method,showed that BSL,BJC and SPSK populations were clustered together with the south type,signifying the southern type of the three C.thalictroides populations.C.shingii forms an independent branch.Genetic distance analysis demonstrated that the genetic distance among BSL,BJC and SPSK populations was 0,and the genetic distance between the three populations and the southern type was also 0.The genetic distance between C.shingii and BSL,BJC and SPSK were 0.002.These findings underscore the southern type of the three C.thalictroides populations(BSL,BJC and SPSK)in Hainan Island and provide evidence for the new species of C.shingii.Diverse conservation strategies should be adopted for different C.thalictroides and cryptic species,with priority protection recommended forC.shingii from Hainan Island,China.Protecting native habitats of C.shingii and the three populations of C.thalictroidesis the most effective conservation strategy.