Submitted to: Proceedings of Florida State Horticultural Society
Publication Type: Proceedings
Publication Acceptance Date: 4/15/2011
Publication Date: 5/2/2011
Citation: Umar, G., Vasanthaiah, H.K., Kambiranda, D., Basha, S.M., Phills, B.R., Hunter, W.B. 2011. Assessment of genetic diversity among selected raspberry cultivars. Proceedings of Florida State Horticultural Society. 123: 26-28. Interpretive Summary: Raspberry production in the southern U.S. requires tolerance to high temperature coupled with low chilling requirement ( less than 500 hrs, below 45 °F) for flowering and fruit set. The major problem associated with cultivation of raspberry in Florida is prevalence of hot and humid conditions. This has significantly hampered the successful cultivation of raspberry as they are cold-loving plants. Therefore a study was carried out to identify the diversity among raspberry cultivars related to their heat tolerance ability, which will aid in the breeding program at Florida Agricutlural and Mechanical University. A selection scheme or genetic analysis based on phenotype is a function of the heritability of the trait, factors like environment, traits of multigenic and quantitative inheritance, or partial and complete dominance often confound the expression of genetic traits. Many of these complications of a phenotype-based assay can be overcome through direct identification of genotypes with DNA-based genetic diagnostic assays as developed here. Of the 100 primers screened, 10 primers yielded 142 usable DNA markers. These data showed the functionality of these RAPD markers for assessing genetic diversity among raspberry cultivars. Further studies coupled with field analysis now can identify low-chill/high temperature fruit set raspberry genotypes useful for developing raspberry cultivars suitable for subtropical environments, such as occurs in Florida.
Technical Abstract: Genetic markers, Random Amplification of Polymorphic DNA (RAPD), were developed for screening raspberry for cold/heat tolerance. Growing raspberries in southern United States is a challenging task as they are high chill-loving plants. Cultivation of raspberry in Florida is significantly hampered due to prevailing hot and humid conditions. The characteristics of raspberry cultivars have been categorized based on morphological descriptions that are dependent on the environment. With this view our program is geared toward identifying low chill/high temperature raspberry genotypes. In this regard, genetic diversity among raspberry cultivars being evaluated in our breeding program for low-chill/high temperature tolerance was assessed employing molecular techniques. A high quality DNA was isolated from raspberry leaf tissue and subjected to molecular analysis. DNA typing was carried out using a RAPD assay. Of the 100 primers screened, 10 primers yielded 142 usable DNA bands suitable as markers. Pairwise comparisons of unique and shared amplification products were used to construct a phylogenetic tree using Euclidean linkage distances that clearly separated low- and high-chill raspberry genotypes. These data showed the potentiality of RAPD markers for assessing genetic diversity among raspberry cultivars. Further studies coupled with field analysis now can identify low-chill/high temperature fruit set raspberry genotypes useful for developing raspberry cultivars suitable for Florida.