Genetic Diversity among Mango (Mangifera indica L.) Genotypes in Hormozgan Province Using Morphological and ISSR Markers

Assessment of genetic diversity in Mango can provide a platform to deepen our knowledge about its genetic background and determine the high quality genotypes for involving in the inbreeding programs. The high observed diversity among native landraces of mango can be used in breeding programs to produce better cultivars and utilization of these cultivars as donor parent to transfer desirable characteristics to high-bearing cultivars. Suitable mango cultivars to prepare rootstock and scion and resistant cultivars against diseases and the high yielding cultivars (with regards to alternate bearing in mango) can be recognized by better understanding of available germplasms. In the past two decades in southern Iran, the process of producing the grafted mango trees via seed culturing and grafting suitable cultivars (What has been registered such as Sindary and Langra and what has not been registered) on the seedlings has been accelerated. Therefore, studying the diversity of mango germplasms in these regions can be a good way to identify and distinguish these genotypes. In the present study, native genotypes of mango from Minab and Rudan counties (Hormozgan Province) were collected, which are mainly produced through seed and over time they have been propagated by vegetative methods based on the quality and taste and their diversity, was evaluated using morphological attributes and molecular markers. In this experiment, we studied genetic and morphological diversity of 39 mango genotypes collected from Minab and Rudan counties (Hormozgan province) using ISSR markers and morphological attributes. Morphological characteristics were assessed using IBPGR descriptor. DNA extraction was done using modified CTAB method. Similarity coefficient of ISSR markers was calculated by Jaccard’s procedure. Polymorphism information content (PIC) was calculated using PIC=2fi(1-fi) formula, where fi was frequency of the amplified bands and 1-fi was frequency of the null bands. In order to analyze morphological data SAS 9.1 software was used and the means were compared using LSD test. In addition, it was prepared a 0 and 1 matrix from morphological data and dendrogram of morphological attributes was designed using Jaccard’s similarity coefficient. The dendrogram inferred from morphological characters grouped all genotypes in eight main clades in which similarity of the dendrogram ranged from 0.12 to 0.83 with mean value of 0.54. The least similarity was observed between Almehtari and Charak, and the most similarity was observed among Moshk, AnaMG, Noghal and HalMG. Analysis of 21 morphological parameters in the studied genotypes demonstrated being of significant differences among these genotypes in terms of morphological attributes (except flower density and inflorescence shape). The ISSR primers produced totally 145 scorable bands that the highest and lowest polymorphism band were observed in MI808 (20 bands) and MI827 (6 bands) primers, respectively. Average of PIC was 0.450. The similarity for ISSR markers ranged from 0.31 to 0.90, in which the least similarity was observed between Majlesi and Charak. However, the highest similarity was observed between Gilasi and KalanMB genotypes. It was observed the differences among same genotypes grown in the various regions. In Rudan region in due to better quality of irrigation water as well as sufficient and proper availability to irrigation water, growth conditions for mango trees is better than Minab region. These differences between Rudan and Minab regions in viewpoint of growth conditions can be reason of morphological diversity among mango similar genotypes in both regions, which it has been caused to incompatibility of morphological and molecular markers. For this reason, the genotypes that are genetically similar to each other may have different morphological differences and/or two homonymous genotypes in two regions have significant genetic differences. For example, Clanfar Baziari genotype, which had high genetic similarity (0.90) with Gilasi genotype, had morphological similarity coefficient equal 0.37 together. However Gilasi genotype collected from Ahmadabad Minab had same ecological similarity with Baziari region. In other instant, genetic similarity coefficient of AnaMG genotype was 0.85 with ShozMD, while in these genotypes had 38% morphological similarity. Correlation coefficient between similarity matrix of ISSR and morphological markers was 0.336 and not significant. It seems that the observed high diversity among morphological attributes is intrinsically and stemming from mango propagation procedure in which mango genotypes highly diverged due to seed propagation. The high genetic diversity showed by morphological attributes was also corroborated by ISSR markers, indicating low environmentally influence-ability of the attributes.