Fatemeh Davoodi; Mehdi Rezaei; Parviz Hidari; Hossein Hokmabadi
Abstract
Introduction: Iran is known as the origin of Persian walnut in the world, and so the study of genetic diversity, identifying and introducing superior walnut genotypes from the main walnut production areas in Iran is very important. From the beginning of the year 2001, seeds of selected walnut genotypes ...
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Introduction: Iran is known as the origin of Persian walnut in the world, and so the study of genetic diversity, identifying and introducing superior walnut genotypes from the main walnut production areas in Iran is very important. From the beginning of the year 2001, seeds of selected walnut genotypes from important walnut production area of Iran were collected and cultivated in a walnut collection in Semnan Research Center (Shahrood), Iran. From this collection, promising walnut genotypes were selected based on climate adaptability to Shahrood area and pomological characteristics. In this research, in addition to introducing fruit characters of these walnut selected genotypes, genetic diversity and their genotypes relationship in the genome level have been also investigated with the ISSR markers.
Materials and Methods: 40 selected genotypes of important walnut regions of Iran (Tuyserkan, Orumieh, Karaj and Khorasan province) were cultivated in a walnut collection at the Shahrood Research Center in 2001. From these seedlings, 21 genotypes were selected on the base of pomological characteristics and they were grafted onto Persian walnut seedlings. Pomological traits of the fruits of these selected genotypes including the average of nut weight, kernel weight, kernel percentage, shell attachment to the kernel, kernel color, shell thickness and nut size and shape were measured. DNA was extracted from young leaves of walnut genotype by CTAB method and its quality and quantity evaluated on the agarose gel as well as the Nano drop, and then genomic DNA was amplified with the 10 ISSR primers in PCR. The amplified bands were separated by Metaphor agarose gel and stained with Ethidium bromide. For each primer, the amplified band range, the total number of bands, the number of polymorphic bands, the polymorphic percentage, Average informative band (AvIb) and resolving power (Rp) was determined. UPGMA dendrogram based on Jaccard similarity matrix was the performance by Ntsys 2.0 software. Principle Coordinate analysis was performed based on the genetic distance matrix with GenAlex 6.2 software.
Results and Discussion: The mean of fruit and kernel weight in selected walnut genotypes were 14.34 and 7.33 g, respectively. The highest nut and kernel weight was found to be 17.5 and 10.3 g, respectively in OR23. The Kernel weight was more than kernel weight reported by Shamlu et al. (2015), Yarilgak et al. (2001) and Tasmuris et al. (2002) (9.40, 8.88 and 6.32 g). The average of kernel percentage in selected walnuts was 51.5%. The highest percentage of the kernel (62.7%) was observed in T12 genotype. from the ten ISSR primers in 21 walnut genotypes, 112 DNA fragments were amplified and 102 DNA bonds of them were polymorphic and they were used for genetic variation analysis. The highest number of amplified DNA bands was observed in UBC826 and UBC888 primers with 14 bands. The highest average band informative (AvIb), 0.62, was observed in UBC887 and UBC886 primers. The highest resolving power (Rp) was found to be 7.71 in UBC826 primer and then in UBC.887 primer. The Jaccard' similarity coefficient of genotypes varies from 0.51 to 0.88. The results showed that the genetic distance of selected genotypes of walnut is medium. The dendrogram analysis of 21 genotypes of walnuts was divided genotypes into two main groups and three subgroups in the first group, which greatly matched the results of the PCoA. The genotypes were collected from Shahrood were inserted on the first subgroup of GI in dendrogram analysis, except of KH4 and OR37 genotypes, and the highest genetic similarity was observed between some of these genotypes (R1G2 with R2G1 and R1G7). The second group includes genotypes KH34, OR26, and SH1. Subgroup 3 of the first group contains R2G8, K26, OR23, T12, and K28. The second group has high genetic distances including R2G4, KH31, T1, OR4, and T9.
Conclusion: The ISSR marker technology is an inexpensive, easy and satisfactory way to evaluate genetic relationships and genetic variation among walnut cultivars. The results of this research showed that these markers (ISSR) are suitable for study of variation in walnut genotypes. The genotypes collected from Shahrood had a lower genetic diversity, and the observed diversity is probably related to human interactions. The Tuyserkan and Urmia genotypes showed more genetic variation. The results of clustering based on molecular markers were largely matched with the grouping based on qualitative traits. The results showed that there is a moderate genetic distance between selected walnuts genotypes. The genotypes collected from Urmia and Tuyserkan regions have a higher genetic distance than other genotypes and which according to their superior characteristics, they can be used as parent along with selected walnut genotypes from the Shahrood area in a breeding program.
Fatemeh Shamlo; Mehdi Rezaei; Abbas Biabani; Ali Reza Khanahmadi
Abstract
Introduction: Persian walnut (Juglans regia L.), a monoecious tree with a long history of cultivation in Middle East and Europe, is currently one of the major nut crops in Iran. Since Iran is known to be one of walnut origins, a high genetic diversity can be found in this area. Almost all traditional ...
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Introduction: Persian walnut (Juglans regia L.), a monoecious tree with a long history of cultivation in Middle East and Europe, is currently one of the major nut crops in Iran. Since Iran is known to be one of walnut origins, a high genetic diversity can be found in this area. Almost all traditional commercial walnut orchards in Iran propagated by seed, therefore these orchards are rich in genetic resources. Morphological studies on the basis of pomological traits can be used for assessment of genetic variability in fruit trees, as well as for selection superior genotypes. Some researchers studied walnut genetic diversity in several areas of Iran but not in Azadshahr region, an area located in north and north-eastern of Iran with high walnut production. As walnut is highly diverse due to open-pollination system and seed propagation, we intend to study genetic diversity of Azadshar walnut genotypes by using morphological and pomological traits.
Materials and Methods: This research was conducted in Azadshare, Golestan province, Iran in 2012. Considering walnut orchards distribution, distance and height above sea level, four areas, namely Vamenan, Kashidar, Roodbar and Sidabad, with the distance of 15 Km apart were selected. Based on tree density and distribution, 15 to 40 trees in each area were labeled, and 102 walnut genotypes were generally evaluated. In each genotype, 30 morphological characteristics related to fruit, leaf and tree-growing habit were studied by using IPGRI walnut descriptor with a few modifications. Data analysis was performed by SPSS 16 software. Correlation coefficient of quantitative and qualitative characteristics was performed by using Pearson and Spearman methods, respectively. Cluster analysis was also performed by Ward method.
Results and Discussion: The results of anatomical characteristics analysis showed that genotypes of this area have high diversity in some pomological traits such as kernel percentage, nut weight, kernel color, easy separation of kernel. Based on the results, genotypes Ka17 and Va31 had the highest average of nut weight (19.79 gr). Va31 genotype had the heaviest kernel (9.4 gr). SID1 genotype had the highest kernel percentage (60.34%). Moreover, e genotypes ROOD4 and Va34 were typified by easy removal of kernel halves (very easy) and fruit flavor desirability (desirable). 26.47% of the genotypes showed very easy separation of kernel from shell. Correlation analysis showed that there was significant correlation among some traits. Fruit weight had high positive correlation with fruit length and diameter, and kernel and shell weight. There was no significant correlation among kernel shape, easy separation of kernel and shell tissue. As the results of cluster analysis of walnut genotypes indicated, clustering of genotypes is mostly similar to collected region and genotypes separated to four main groups in 12.5 distances of 25 in cluster figure. Most walnut genotypes of Vamenan and Kashidat regions, with the exception of ROOD 11 and ROOD 4, were placed in the first and second clusters similar to their geographical distribution. These areas have been the closest to the geographical distance and the height above sea level is not much different from each other. Almost all the genotypes collected from Sidabad region were placed in the third cluster. Sidabad village has high geographical distance from other studied regions, with its elevation is being significantly different from other areas., The majority of Roodbar genotypes, some genotypes of Vamenan and Kashidar, and one genotype of Sidabad (SID4) formed the fourth cluster. Roodbar region was located geographically between Sidabad and Vamenan regions. It has the same elevation as Vamenan and Kashidar have. In general, nut, kernel and leaf characteristics had the major role in clustering of genotypes.
Conclusion: Large genetic diversity in Azadshar walnut genotypes as inferred from morphological markers is advantageous to crop improvement through breeding and selection. Clustering analysis by morphological markers could clearly separate Sidabad walnut genotypes from other populations which have a good similarity with their geographical distribution. According to the results of this study, walnut genotypes collected from Azadshahr region showed a high genetic variation that can be used in breeding programs. Clustering based on morphological characteristics can be an effective method to determine the relationship between genotypes, as well as their relative distance.
Mohsen Mardi; Mehrshad Zeinalabedini; Rohollah Haghjoyan; Seyyed Hassan Jamali; Seyyed Mojtaba Khayam Nekouei; Abdolreza Kavand; Karim Ahmadi; Leila Sadeghi; Ali Akbar Loni; Tayebe Karami; Soghra Khoshkam
Abstract
Due to the complex assessment of young walnut cultivars (Juglansregia L.) based on morphological traits, advance molecular tools have provided a new prospect for cultivar identification and DNA fingerprinting. In this study, specific molecular keys were identified for 5 Iranian walnut cultivars (Juglansregia ...
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Due to the complex assessment of young walnut cultivars (Juglansregia L.) based on morphological traits, advance molecular tools have provided a new prospect for cultivar identification and DNA fingerprinting. In this study, specific molecular keys were identified for 5 Iranian walnut cultivars (Juglansregia L.) using 30 SSR markers. The results showed that 5 SSR markers produced polymorphic bands for studied Iranian walnut cultivars. SSR markers WP-376andABRII-WM-6produced specific molecular keys in walnut cultivars K72, Z30, Z53 and Z60. Due to different genetic background, it was impossible to recommend the B21 and Z67 genotypes as mother’s trees. The specific molecular keys were verified on 39 walnut mother's trees and the results were confirmed at two independent laboratories. The reported specific molecular keys can be used for identification of 5 Iranian walnut cultivars in juvenile period.
