| Kiwifruit(Actinidia Lindl)is a woody vines which is native to China.Being deciduous,kiwifruit shows an obvious xenia effect which has important influence on fruit quality.11 provenances of wild A.eriantha were used for this study.Flower phenotypical traits and pollen traits were carried out to analyze the difference,SSR molecular marker technology was used to analyze genetic diversity and genetic structure at DNA molecular level,and the genetic variation of A.eriantha was discussed,which could provide a basis for genetic improvement and provenance superior selection.Association analysis between genotypes and flower and leaf quality was performed,the molecular markers associated with the target traits were detected.Finally,two male wild A.eriantha were chosen as pollination material for the xenia effect experiment.The study has a certain theoretical and guiding significance for the male selection,fruit yield and quality improvement.The main results are summarized as follows.(1)Investigation of 17 phenotypic traits from 11 wild A.eriantha populations showed significant differences among all the traits both within and between populations.The phenotypic variation coefficient(CV)ranged from 15.71 % to 52.34%.The pollen quantity is the most unstable trait(CV=52.34%),while the corolla diameter is the most stable trait(CV=15.71%).The differentiation coefficient of MGS population is the biggest(CV=33.65%),while the differentiation coefficient of WFS is the smallest(CV=23.63%).The corolla,pollen quantity,and pollen viability were significantly positively correlated.Principal component analysis showed that the pollen quantity,the color of the flower,and the length of flower stems could used to classify.Cluster analysis classified the 11 wild A.eriantha into tree groups without a clear geographic correlation.(2)The pollen grains shape of wild A.eriantha male genotypes were prolate or perprolate,the polar view was trifid circular.Pollen polar axis length ranged from 22.42 to 27.73μm,the coefficient of variation was 4.75%.While the equatorial axis length ranged from 12.73 to 14.31μm,the coefficient of variation was 3.12%.SEM showed all pollen grains were tricolporate including three ectocolpi and three endopori.Ectocolpi were long but narrow at two ends and arranged in a regular longtiudinal pattern.One or two colpi were observed from equatorial view.Three colpi were found from polar view.Colpus width ranged from 7.29~9.52μm,the coefficient of variation was 6.78%.There were significant differences between individual geotypes.According to the NPC(Number,Position,Character)classification system classification,the pollens belonged to N3P4C5 mode.The P/E ratio ranged from 1.65 to 2.06,the coefficient of variation was 4.73%.Three types of pollen surface ornamentation were observed: brain-like(65.22%),irregularly rugulate(30.43%),Warty(4.35%).By using UPGMA cluster analysis,23 genotypes could classified into two groups at similarity distance 3.41 level.One genotype was fell into the first group,the other 22 genotypes could fell into the second group.At similarity distance 2.55 level,23 genotypes could classify into three groups.The No.1 genotype was fell into the first group,No.3,No.4 and No.6 was fell into the third group,the other 20 genotypes could fall into the second group.The pollen grain size of the first group was minimal,the pollen of the third group was the largest.The classification was mainly due to the differences in pollen grain’s shapes.The pollen characteristics suggested that many genotypes were from the same origin.(3)38 pairs of SSR primers were use to analyze genetic diversity of wild A.eriantha.Including 274 ecotypes and 11 populations from Jiangxi province and its environs in China.The results showed that 425 loci were amplified totally by 38 pairs of SSR primers.The mean number of observed number of alleles was 11.18,effect alleles per locus was 4.55.Shannon’s information Index was 1.57.Observed heterozygosity(Ho)were ranged from 0.06~0.89,Expected heterozygosity(He)were ranged from 0.07~0.77.The Genetic differentiation coefficient(Fst)was 0.21.The genetic distance and the genetic identity of the 11 populations were 0.117~0.691 and 0.501~0.889,respectively.(4)Based on the genotyping data of 38 SSR markers on 274 wild A.eriantha germplasm resources,the linkage disequilibrium of pairwise loci and population structure were analyzed.Association between 38 SSR loci and 8 quantity traits were studied by using Tassel 2.1 GLM(General Linear Model)program.A total of 18 SSR markers were significantly associated with 8 quantity traits(P<0.01),some of which were associated simultaneously with many traits,and the rate of explanation on the phenotype of related marker ranged from 8.33%~52.54%.The results also showed that 7 markers associated with the pollination traits,respectively 5,A167,STAD037,ESTAD42,UTH03-04,UDK96-013,and UDK96-053.(5)With male A.eriantha ‘L7’ and ‘M16’ as pollination varieties,cross-pollination experiment was conducted on ‘Hongyang’,‘Jingguo’,‘Jingyan’,‘Jingkui’ and ‘Ganmi6’,with self-pollination as control,the fruit setting rate and fruit characters were investigated.The result shows that there was a significant difference among the pollination combinations in terms of fruit setting,size of the fruit,soluble sugars and vitamin C,but that there were no significant differences with regard to titratable acid content.In this study,a high level of genetic diversity was found in wild A.eriantha male germplasm.The male A.eriantha germplasm could provided materials for the new variety breeding and sustainable utilization of kiwifruit resources.The difference between phenotype and SSR molecular marker results was caused by environmental factors.Correlation analysis was used to identify the SSR markers which associated with phenotypic traits,which can be used for selection of the specific genes.The utilization of male A.eriantha pollen was not suitable for ‘Jingguo’.Further work is needed to verify the xenia within the male A.eriantha and other femal kiwifruit. |
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