Genetic Diversity Study On Silene Conoidea L. And Preliminary Test On Its Resistance To Tribenuron-methyl

ABSTRACT Silene conoidea L.(Caryophyllaceae),an annual herb,is commonly distributed and found in wheat fields and grass lands.It is a kind of broadleaf weeds in wheat fields.In recent years,the number of S.conoidea L.has declined sharply due to the cornfield herbicide use,but S.conoidea L.still happen heavily in some wheat fields.We used self-developed SSR markers and conventional herbicide-resistance identification techniques to study its genetic diversity and herbicide resistance,so as to prevent the resurgence of S.conoidea L.It is of great value to prevent the resistant varieties from happening and spreading.The main results are as follows:(1)We had structured a genomic library containing lots of SSR sequences successfully.After cloning and solid culturing,we checked the positive clones by PCR amplification using M13F and M13R primers and finally,154 positive clones were selected and sequenced on ABI 3730 DNA analyze,of which 121(about 79%)contained SSRs.These primers were tested for polymorphism in 10 individuals which came from the 9 different populations.PCR primers were designed for 30 sequences using program PRIMER 5.0.The Products were checked with 2.0%agarose gels.20 pairs of primers showed the single and clear band.Finally,twenty microsatellite loci were isolated from this species,and thirteen of these were analyzed to estimate the genetic diversity of nine populations of S.conoidea.(2)We analyzed the total 176 individuals of Silene conoidea.in the nine populations with the Arlequin311 software.The results showed that the allele number ranged from 1-19 within groups.For the nine statistical comparison groups,the average number of alleles ranged from 2.9 to 3.9.There was little difference between groups in which the maximum number of alleles FHS group,was 3.9,and the minimum number of alleles WL groups,was 2.9.SQ population had the highest observed heterozygosity(0.515),while the lowest FHS population(0.337).LB population’s expected heterozygosity(0.500)was the highest,while the lowest expected heterozygosity(0.336)population was WX.For all the groups of S.conoidea,the mean observed heterozygosity was 0.415,the mean expected heterozygosity was 0.414.At the species level,the number of alleles ranged from 2-31,with an average of 8.3;observed heterozygosity averaged 0.416,the average expected heterozygosity was 0.509.(3)We also detected the bottleneck effect with the software bottleneck and our results showed that:in IAM,TPM and SMM three models LB group displayed recently experienced a bottleneck effect;in IAM model detected six populations(WX,LB,SQ,KF,XC WL)from long-history herbicide-used area,showed significant or extremely significant heterozygosity excess,may have experienced a bottleneck effect,but never three groups wihout herbicide-used(FHS,LY,HX)showed no heterozygosity excess,in line with the mutation-drift equilibrium,indicating that three regions of S.conoidea populations have not experienced the bottle bottleneck effect.(4)The resistance of S.conoidea populations to tribenuron-methyl was evaluated by both seed-bioassay and whole plant assay.Assays were applied on two populations,Wenxian population with long-hisory herbicide-used and Fenghuangshan population wihout herbicide-used.The result was that Fenghuangshan population generated a certain degree of resistance to tribenuron-methyl.The the resistance factor of Fenghuangshan population was 2.05 by whole plant experimental assay,while its resistance factor was 10.2 by seed bioassay.