Genetic variability studies on avocado (Persea americana L.) using inter-simple sequences repeat (ISSR) analysis

Abstract

Avocado (Persea americana Mill) is an evergreen tree native to Mesoamerica. Open pollination reproduction mode and mutations are the main source of the high genetic diversity in avocado. Differences in climate and soil conditions in Indonesia by region of origin also makes the avocado has a high diversity. Evaluation of avocado characterization is usually based on morphological descriptions of plants. However, this method requires a long time because the avocado plant is an annual plant. Therefore, other ways to characterize the avocado is needed. Inter-simple sequence repeat (ISSR) markers were used to study genetic diversity relationships among 23 avocado accessions. Morphological traits were used to assess levels of polymorphism across 23 accessions. Thirty-four morphological traits were scored and were scattered into 121 different loci. The twenty-third accessions grouped into three groups at 0.44 similarity degree. A total of 37 different amplification fragments were detected ranging from 2 to 7 per primer with an average of 5.2 fragments per primer. A dendrogram was generated using UPGMA (Unweighted Pair Group Method with Arithmetic Averages). This dendrogram classified most of the genotypes analyzed into three major groups. The UPGMA cluster constructed from combination data of morphological traits and ISSR marker analysis separated the 23 accessions into three major groups at similarity value of 0.51. The most different accession is Lam1. The rest of the accessions in the dendrogram could be divided into two main clusters with accessions of different origin intermixed. The correlation coefficient between the morphological and ISSR matrices was 0.60076. It means that the matrices obtained from the molecular genomic markers and the morphological trait had significant positive correlations.