The Formation Of Several Natural Hybrid Ferns And The Technology Of Molecular Identification

Fern,treated as the oldest and the most complex group all over the land,the formation and evolution on it has been taken more attention.And natural hybridization events happened frequently through this group,maybe due to the complex ploidy and multiple breeding patterns.However,in the past years to make sure the species could be hybrids or not,just depend on the differences of morphology,as to describe them directly or found the passing form,then explored the natural hybrids and their parental origin.But there is no molecular data,cytology data applied for the natural hybrid to verify them widely.This article selected one subgenus from Dryopteridaceae,then choose 9 species from Dryopteris Subgen.Erythrovariae,D.Sect.Variae,D.Sect.Erythrovariae,D.sect.Acrorumohra as mainly materials.Used two chloroplast DNA sequences,evolution rate slower coding sequence rbc L and the faster non-coding sequence trnL-F,also added a low copy nuclear DNA sequence PgiC,to make sure the phylogenetic relationship;Combination the morphology results(spores under scanning electron microscopy(SEM),then observed the stoma size with optical microscope,sporophyte morphological comparison),reproductive biology,cytology(tabletting directly,flow cytometer testing ploidy)and so on,to explore the origin of natural hybrid,genetic relationship and study on the mechanism.The hybrid origins of D.dehuaensis and D.fuscipes were found for the first time,and also found a new hybrid which is hybridized by D.gymnophylla and D.jishouensis.Showed the experiments' results like these:D.dehuaensis is a natural hybrid,then could know that female parent is D.shiakeana,and D.varia is the male parent,spores could be fertile,there are numbers of archegonia but no antheridium,thus it could be breed by parthenogernesis,apomixia;through the ploidy result,found that D.dehuaensis may could be a perfect species for proving the triploid cycle hypothesis.D.erythrosora and D.championii are the parental origin for natural hybrid D.fuscipes.However,due to the backcross by natural hybrids and parents repeatedly,introgressive happened,then we get the conclusion like this both D.erythrosora and D.championii could be the male or female parent;and introgressive for a long time,may caused that hybrid could be purified the genetic information from its parents gradually,and then being a ‘pure'species.According to the distribution areas and nuclear sequence about D.gymnophylla and D.jishouensis,we thought that there is a hybrid zone during the Wuling mountains which formed by their hybrid;but when we analysed the chloroplast DNA,could find that hybrid and its parents didn't differentiate obviously,so another possibility maybe exist,just because of the introgressive or the changeable ploidy,led to D.gymnophylla differentiation into D.jishouensis and Dryopteris sp..The research of the natural hybrid on D.Subgen.Erythrovariae,Dryopteridaceae,not only provided the necessary evidence for evolution of complex family,but also could solve the difficult taxonomic problems caused by the hybrid's transitional form,then provided the necessary basic data for species formation and reticulate evolution at the same time,furthermore,provided a theoretical basis and technical support for the species conservation and breeding.