Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2008
Publication Date: 7/1/2008
Citation: Stover, E.W., Gottwald, T.R., Hall, D.G., Aradhya, M.K., Zee, F.T., Crane, J. 2008. Guava SSR analysis: Diversity assessment and similarity to accessions associated with reducing citrus greening in Vietnam. HortScience. 43:1119.
Technical Abstract: The guava (Psidium guajava) is an evergreen tree in the Myrtaceae, native to tropical America. It is grown throughout the tropics and subtropics of the world, and is used as a fresh fruit and processed into juice, jelly and paste. Recent introduction of citrus greening (huanglongbing) into Florida has renewed interest in guava, since closely interplanting citrus and guava in Vietnam appears to greatly slow progression of citrus greening. It is hypothesized that guava volatiles may repel the greening vector, Asian citrus psyllid (Diaphorina citri). SSR analysis was conducted on all readily accessible US guava accessions, as well as material (‘Bom’ and ‘Xaly nghi’) from Vietnamese citrus/guava orchards. Accessions numbered 73 distinct sources. Nine SSR primer pairs, identified by Risterucci et al., were used. Thus far, 14 accessions have not amplified well in PCR. Alleles per locus ranged from 4 to 8, with an average of 6.2. Only 40 genotypes were identified, since several accessions were synonymous. Cluster analysis using the neighbor-joining method revealed four distinct affinities. The genetic differentiation within and among the groups showed marked differentiation (FST = 0.325) and inbreeding was slight (FIS = 0.154). The Vietnamese accessions were in the two most closely related of the four clusters. It was important to identify US material closely related to the Vietnamese accessions, since they will be quarantined for two years and research on delaying greening is an immediate priority. Some commercial guavas in Florida (‘White Indonesian Seedless’ and a group called Thai White guava) are in the same clusters as the Vietnamese cultivars. Even more closely related material is available within the US. Presence of the Vietnamese cultivars in two clusters suggests that the properties of interest may be broadly distributed among cultivated guavas. It is also possible that the markers assessed do not correlate well with the trait of interest.