نوع مقاله : مقاله پژوهشی
نویسندگان
1 گروه تولیدات‌گیاهی، دانشکده علوم کشاورزی و منابع طبیعی، دانشگاه گنبدکاووس، گنبدکاووس، گلستان، ایران
2 ایستگاه تحقیقات زیتون طارم بخش تحقیقات علوم زراعی و باغی، مرکز تحقیقات و آموزش کشاورزی و منابع طبیعی استان زنجان، سازمان تحقیقات، آموزش و ترویج کشاورزی، طارم، زنجان، ایران
چکیده
کلیدواژه‌ها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
This research was conducted to investigate the genetic diversity and the relationship between molecular markers and fruit-related traits in 98 olive genotypes during 2019-2021 at Gonbadkavous University. Nineteen growth and morphological traits of 150 olive fruits associated with each genotype were assesed. All the investigated traits showed significant differences among olive genotypes at the 1% probability level, indicating a high level of genetic diversity among the genotypes. Mean comparisons showed that 'Caridolia' and 'D1' genotypes exhibited greater fruit length and diameter, while 'D1' genotype also demonstrated superiority in fruit weight, fruit flesh weight, and stone weight. The 'Amygdalolia' genotype showed the greater stone length. The most significant positive correlations were observed between fruit length and diameter (0.909*), as well as between fruit flesh weight and fruit weight (0.994*). The results of regression analysis demonstrated that fruit flesh weight and stone weight had the strongest correlation with fruit weight at a 1% probability level. Additionally, fruit weight, flesh-to-stone ratio, fruit diameter, and flesh thickness were found to be most closely associated with the weight of the fruit. According to the results of cluster analysis, genotypes were classified into four distinct groups based on their fruit characteristics, with the third group demonstrating superiority in the majority of these traits. The results of association analysis involving CAAT, ScoT, ITS, and IJS markers in relation to the studied traits revealed that multiple alleles are responsible for controlling fruit length, fruit symmetry, nipple, stone shape, number of grooves, and stone weight. Among these traits, fruit symmetry, nipple, and number of grooves had the highest cumulative coefficient of determination. The allele SCoT21-B showed the strongest association with nine traits, followed by the allele IJS9-A with five traits. The findings from this research can be utilized in breeding programs to develop olive cultivars that show improved yield.
کلیدواژه‌ها [English]
Extended Abstract
Introduction
The Olive tree (Olea europaea L.) is among the oldest cultivated plants found in the Mediterranean region. Owing to scientific progress and heightened awareness, the consumption of olives has grown significantly. Olive oil, which is rich in oleic acid, is esteemed for its therapeutic and medicinal properties. In Iran, olives are particularly important due to their high oil content. Understanding different genotypes and their relationships are crucial for genetic studies, and this require examining both morphological and employing molecular markers. Morphological traits, such as fruit characteristics, are crucial as they reflect the genetic makeup of the plant and its interaction with the environment. Molecular markers, which can be easily measured, are also powerful tools for identifying genotypes and assessing genetic diversity. This study explored the extent of genetic diversity in a large collection of olive germplasm utilizing morphological characteristics of fruit and molecular markers. The findings of this study could be valuable for olive breeding programs, helping to select parent plants with desirable traits for improved yield, quality, and disease resistance.
Materials and Methods
A total of 89 olive genotypes cultivated in Tarem Olive Research Station of Zanjan Province, Iran were analyzed in this study during 2019-2021. To evaluate the characteristics of fruit length, fruit diameter, fruit symmetry, fruit shape, position of maximum diameter, fruit apex, nipple, presence of lenticels, size of lenticels, site of color change initiation, flesh thickness, flesh-to-stone ratio, stone length, stone shape, number of grooves, stone apex, fruit weight, fruit flesh weight, and stone weight, the sum of 150 fruits from each genotype were selected. For the purpose of molecular analysis, fresh and young leaves of olive trees were collected for DNA extraction. The leaves were powdered with the aid of liquid nitrogen and extracted using the CTAB method. The quality of DNA was assessed through horizontal electrophoresis with 0.8% agarose gel. PCR reactions were performed using CAAT, ScoT, ITS, and IJS markers. SPSS software version 24 was used to analyze the relationship between morphological traits and the analysis between morphological and molecular traits.
Results and Discussion
All the investigated traits showed significant differences among olive genotypes at the 1% probability level, indicating very high genetic diversity among the genotypes. The results of mean comparisons showed that “Caridolia” and “D1” genotypes demonstrated the greatest fruit length and diameter, while 'D1' also excelled in fruit weight, fruit flesh weight, and stone weight. The 'Amygdalolia' genotype had the longest stone length. The highest significant positive correlations were observed between fruit length and diameter (0.909*), as well as between fruit flesh weight and fruit weight (0.994*). Additionally, there was a positive and significant correlation between fruit weight and stone weight (0.842) at the 1% probability level. The finding of regression analysis, considering fruit weight as the dependent variable and other traits as independent variables, showed that fruit flesh weight and stone weight had the highest correlation with fruit weight at the 1% probability level. Furthermore, fruit weight, flesh-to-stone ratio, fruit diameter, and flesh thickness were most related to fruit weight. Cluster analysis divided the genotypes into four groups based on fruit traits, with the third group being superior in traits such as fruit length, stone length, fruit weight, fruit flesh weight, stone weight, fruit diameter, flesh thickness, flesh-to-stone ratio, size of lenticels, and number of grooves. Association analysis between molecular markers and various traits revealed that fruit length, fruit symmetry, nipple, stone shape, number of grooves, and stone weight were controlled by multiple alleles. Among these traits, fruit symmetry, nipple, and number of grooves had the highest cumulative coefficient of determination. The strongest association of the alleles to traits was obtained from allele SCoT21-B and IJS9-A with nine five traits, respectively.
Conclusion
This study revealed significant genetic diversity among olive genotypes, with 'Caridolia' and D1 genotypes showing superior fruit traits. Strong correlations were found between key traits, and regression analysis highlighted fruit flesh weight and stone weight as major factors influencing fruit weight. Molecular marker analysis identified important alleles, with SCoT21-B showing the strongest association with multiple traits. These findings are valuable for breeding programs aimed at improving olive cultivars.
Author contributions
A.R. Dadars and H. Sabouri carried out the planning and design of the experiment. Experimental sample collection was carried out by A.R. Dadars. A. Tanhaei conducted the experiments. A.R. Dadars, H. Saboor, and S.J. Sajadi analyzed the data. A. Tanhaei, H. Sabouri, and A.R. Dadars wrote the initial draft of the manuscript. A.R. Dadars, H. Sabouri, and S.J. Sajadi contributed to the interpretation of the results. All authors provided critical feedback and made significant contributions throughout all stages of the research, data analysis, and manuscript completion.
Data availability statement
Data available on request from the authors
Acknowledgements
The authors would like to express their gratitude and appreciation to the Olive Research Station of Tarom County and the Agricultural Research Center of Zanjan Province for their collaboration in providing the plant materials for the present research.
Ethical considerations
The authors avoided data fabrication, falsification, plagiarism, and misconduct.
Conflict of interest
The authors declare no conflict of interest.
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