Dissertation > Biological Sciences > Botany > Plant Cell Genetics

Study of Genetic Diversity of Elymus Species

Author YanXueBing
Tutor ZhouHe;Wang
School China Agricultural University
Course Grassland
Keywords Elymus morphological trait allozyme microsattelite genetic diversity
CLC Q943
Type PhD thesis
Year 2005
Downloads 351
Quotes 27
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Genetic diversity of 40 populations of 9 Elymus species from China were determined using morphology,allozyme and mocrosattelite markers for 28 morphological traits,seven allozyme loci and eleven microsattelites. Morphological data showed, growth and development of E.populations were faster in contrast with their origins and development period of populations from regions of cold and high elevation was shorter than from warm and low-elevation regions. Species of Sect.Turczaninovia (Nevski)TzveI.)finished the growth lately(mainly during mid July) and were adapated to the culture condition as well as E. sibiricws.Morphology differed greatly among popultions and variation trend also changed with species,populations and morphological traits. Distance between boot leaf and ear, growth rate during seedling to tiller, spikelet petiole and plant villus grade had great variation within species.Ear shape, ear pitch number, plant height and palea had steady performance. Dendrogram of relationships showed, E.dahuricus Turcz., E.cylindricus(Franch) Honda and E.purpuraristatus C.P.Wang et H.L.Yang varied to a great extent and populations of E.nutans Griseb.L.and E.sibiricus Linn.clustered clearly within the species.Senenteen eigen vectors reflecting more than 85% of total variation of variable morphological traits can be divided into 10 principal component levels based on their cumulatives.Allozyme data indicated that, 7 allozyme loci were encoded by 22 alleles across 40 populations. Polymorphic loci percentage was 87.5% at genus level and ranged from 16.67% to 83.33% at species level.Mean of diversity index was 0.0830 ranging from 0.0210 (EST-2) to 01520 (AAT-2) within populations(Hs),0.2149 ranging from 0.1075 to 0.2694 among populations(Dst ).Coefficient of genetic variation across all polymorphic loci was 0.7213 ranging from 0.3075 (AAT-2) to 0.9111 (EST-2). Genetic diversity(He) and Shannon’s information index (I)had biggest variation values (He=0.2974; I=0.4565) among populations of Elymus genus,ranged from 0.0800 to 0.2528 and 0.1173 to 0.3769 at species level, from 0.0160 to 0.1680 and 0.0250to 0.2433 within population, respectively. Genetic diversity(He) and Shannon’s information index (I) were far lower within populations within each species, ranging from 0.0400 to 0.0960 and 0.0587 to 0.1424,than among populations. 38.9%, 33.2% and 29.8% of total genetic variation of Elymus genus existed amonng species,populations within the species and individuals within a population respectively.Gene flow among populations was very low, 0.1932.Genetic distance among 40 populations showed great extent from 0.0365 to 0.7612.Populations belonging to the same species almost clustered and the dendrogram was obviously related to the geographical origins.Nine E.species were not divided into two groups, Sect.Turczaninovia (Nevski) Tzvel.) and Sect.Elymus,however E.species of the same Sect.had close relationships.Elevation(P<0.01) had greater influence than geographical site(latitude and longitude ) (P<0.05) on the genetic difference. Microsattelite data indicated that 11 polymorphic SSR loci were encoded by 38 alleles, ranging 1 to 8 alleles. Microsattelite primers developed from E.species showed the allele mean of 4.5 more than 2.2 from wheat.At the same time, Microsattelite primers developed from E.species had better function in determining the genetic diversity of E.species. Loci ECGA22、 ECGA114、 EAGA51 and WMS43 reflected high genetic variation, helping to the construction of fingerprint of E.species.Genetic similarityof 40 E.populations tested ranged from 0.1622 to 0.3619. Primers consistently indicated that 75.74% of the variation existed among populations within the species.Tibetan plateau was genetically resourceful of E. species both allozyme and SSR markers. Gene diversity and Shannon’s information index at species level varied greatly from 0.1622 to 0.3619 and 0.2248 to 0.5318,respectively.Similarity and dendrogram of clustering among populations showed consistence with their species and geographical origins.9 E.species were not clea

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