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- Author or Editor: Samir Mhameed x
- Journal of the American Society for Horticultural Science x
The detection of association between DNA markers and traits of interest in an outbred population is complicated and requires highly polymorphic markers. A genetic linkage map of avocado (Persea americana Mill.) recently generated consists of simple sequence repeat (SSR) markers as well as DNA fingerprint (DFP) and randomly amplified polymorphic DNA (RAPD) markers. These markers were used to detect putative quantitative trait loci (QTLs) of eight avocado fruit traits. Two statistical methods were used: one-way analysis of variance and interval mapping. Six traits were found to be associated with at least one of the 90 DNA markers. Based on the two statistical approaches, a putative QTL associated with the presence of fibers in the flesh, was found to be located on linkage group 3. This putative QTL was found to be associated with the SSR marker AVA04 having a high significant value (P = 4.4 × 10-8). The haplotype analysis of linkage group 3 showed a putative dominant interaction between the alleles of this locus.
To estimate heterozygosity level in the avocado (Persea americana Mill.) genome, two types of variable number of tandem repeat (VNTR) markers were used. Multilocus DNA fingerprints (DFPs) were analyzed on avocado progeny resulting from either crosses or selfing of cultivars. In five crosses, heterozygosity was 100%, while in two self-pollinated families, heterozygosity was 90% and 94%. Single locus, simple sequence repeat (SSR) DNA markers were analyzed by typing 59 loci on five avocado cultivars. Average heterozygosity varied from 0.50 to 0.66, while gene diversity varied from 0.42 to 0.66. Heterozygosity varied from 38% to 70%. The percentage of fragments that exhibited Mendelian inheritance was 62.5% to 85% (P < 0.05) for the DFP fragments and 85% for the SSR alleles.