| B-biotype Bemisia tabaci is an important agricultural pest in the world. The AFLP marker was used to analyse the genetic variation among different samples which were rearing 21 months, 29 months and 36 months separately collected from 5 host plants. Meanwhile, the SRAP marker was used to validate the result of 25 months sample. The main results were as follows:(1) 5 pairs of AFLP primers were used to analyse genetic diversity among 21 months, 29months ans 36 months. The result showed that the genetic diversity of the 29 months and 36 months sample has certain increase when compared with 21months sample. We found genetic diversity of the population from the poinsettia was higher than that of other populaions. At three stages, the gene diversity, polymorphic allelic loci and Shannon index of diversity of the poinsettia were higher than those of other host plants. It showed that the gene diversity of poinsettia was rising.(2) The average Fst of five populations was 0.4598,0.3286,0.3711 in 21 months, 29 months and 36 months, respectively. The range of Fst was 0.4978 - 0.5449, 0.0741 - 0.5425, 0.1556 - 0.6570, respectively. There was significant genentic differentiation among different host plant populations. Cabbage population and tomato population were always clustered together in different time which showed that there were very smaller genetic distance and higer genetic identity. Poinsettia population was a clade which showed that there were very higer genetic distance and smaller genetic identity with other populations.(3) It showed a remarkably genetic differentiation within populations. In different time, there was significant genentic differentiation among tomato population (Fst21-29=0.5449, Fst21-36=0.5269), cabbage population (Fst21-29=0.4287, Fst21-36=0.5861), cucumber population (Fst21-29=0.5356, Fst21-36=0.5866), cotton population (Fst21-29=0.5478, Fst21-36=0.6260) and poinsettia population (Fst21-29=0.5192, Fst21-36=0.5990). Excepting tomato population, the genentic differentiation of other populations was increasing. The change trend of genetic distance, genetic similarity and gene differentiation coefficient among different rearing stages was almost the same. Namely, the population with big gene differentiation coefficient has long genetic distance and small genetic similarity. Through genetic similarity analysis among different individuals in the same population, we found B. tabaci were genetically changed even feeded with the same plant host.(4) Sequence-related amplified polymorphism was simple, with a reasonable throughput rate, disclosing numerous co-dominant markers, and a prefered random amplification of coding regions in genome. 218 bands were amplified by 10 SRAP random primers, of which 162 bands were polymorphic loci, and the percentage of polymorphic loci was 74.31%. The Shannon index of diversity (I) was 0.3984, and Nei's gene diversity (H) was 0.2684, which showed high gengtic diversity at species level. There was significant differentiation among different populations because average Fst in five populations was 0.6976. Through genetic similarity analysis among different individuals in the same population, we found B. tabaci were genetically changed even feeded with the same plant host. UPGMA cluster analysis indicated that 5 populations could be divided into two groups. Tomato, cotton, cucumber, and cabbage populations clustered together, whereas poinsettia population clustered into a unique clade. Therefore, it showed that host plant was a factor affecting genetic variation of B. tabaci.We primarily studied genetic differentiation of B-biotype B. tabaci feeding on five host plants using AFLP and SRAP in this paper. We concluded that host plant was an important factor affecting genetic structure of B. tabaci population.
|
PDF Full Text Request