Morphological Characters And SCoT Analysis Of Genetic Relationships Among 40 Accessions Of Guava Germplasm

Owing to specific growth characteristics and climate,guava only survivals in south subtropical region of China.Guava,small fruit trees,was not valued for years.In China,studies on guava start relatively late.This severely limited its development in business.Collecting,evaluating and protecting germplasm resources have significantly important effects on utilization and breeding of guava.In view of this,we designed this experiment to evaluate germplasm resources of guava,and investigate their genetic diversity and relationship.Results are as follows:43 morphological features were detected in our study,including 15 quantitative characters and 28 qualitative characters.Results revealed that coefficients of variation in guava were high,and among quantitative characters,coefficient of variation of stem length was highest,peaking at 62.83%.They could be divided into 4 group according to leaf morphology:Lanceolate leaf、Fusiform leaf、Near circular leaf、Oblong leaf.Which was in line with the results of UPGMA dendrogram at 0.74 in heritability coefficient based on SCoT molecular marker After evaluating integrated fruit quality,Sijihong guava、Banye guava、new Zealand guava、pearl guava and Nanning local guava No.1 quality were better,and fit to be planted.We compared the results of extracting DNA by using 3 different concentrations of CTAB solution(2%,3%,4%)to develop CTAB method in extracting guava DNA.Results suggested that the best concentration of CTAB solution was 2%.Besides,we suggested that burgeon was more suitable for DNA extraction compared with tender leaf and old leaf.11 rich and stable polymorphic primers were screened out from 70s ISSR primers,from which 117 bands were amplified,among which there were 107polymorphic bands,the polymorphism percentage were 91.45%.Amplification results can be well distinguish 40 guava germplasm,the genetic similarity coefficient of all materials ranged from 0.67to 0.92,and the average genetic similarity coefficient was 0.795.At the genetic similarity coefficient 0.70,40 germplasm resources were divided into 3 groups,At the genetic similarity coefficient 0.74,the second groups can be divided into 3 subgroups.The results are consistent with the morphological classification.