Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 56 3 2025 09 23 Genetic Study of Molecular Marker(s) Linked to Rhizoctonia Root Rot Resistance Genes in Sugar Beet (Beta vulgaris L.) Genetic Study of Molecular Marker(s) Linked to Rhizoctonia Root Rot Resistance Genes in Sugar Beet (Beta vulgaris L.) 111 125 105497 10.22059/ijfcs.2025.388142.655120 FA Mastaneh Sharifi Agronomy and Plant Breeding Department , College of Agriculture and Natural Resources, University of Tehran. Karaj. Iran 0009-0008-8668-6280 Alireza Taleei Agronomy and Plant Breeding Department , College of Agriculture and Natural Resources, University of Tehran. Karaj. Iran 0000-0001-7143-6694 Peyman Norouzi Sugar Beet Seed Institute, Agricultural Research, Education and Extension Organization (AREEO), Karaj, Iran. MohammadReza Naghavi Agronomy and Plant Breeding Department , College of Agriculture and Natural Resources, University of Tehran. Karaj. Iran MohammadMehdi Faghihi Plant Protection Research Department, Fars Agricultural and Natural Resources Research and Education Center, AREEO, Shiraz, Iran Journal Article 2025 01 05 Introduction. Sugar beet is the main source of sugar with about 35% of the world's sugar production. It is affected by various pathogenic factors. The most important pathogens that lead to sugar beet root rot is the Rhizoctonia solani fungus, which exists in many areas of sugar beet cultivation. Given that conventional breeding methods for resistance to this disease are difficult and time-consuming, the development and identification of resistance-associated markers and the determination of the locus controlling resistance to this disease can significantly accelerate root rot resistance breeding programs and provide a new perspective for plant breeding advances. To achieve resistant cultivars, the development of markers related to resistance can help breeding programs. In this regard, the aim of this research is to identify molecular markers associated with rhizoctonia resistance genes to accelerate the screening of sugar beet breeding materials. Materials and Methods. In this study, 20 pairs of primers were used to investigate 10 susceptible and 10 resistant plants from two F2 populations in order to identify molecular markers linked to the resistance gene to rhizoctonia root rot of sugar beet. The primers were examined in terms of band pattern and the bands were scored based on their presence or absence (zero and one). DNA extraction was performed using Modified Dellaporta et al. (1983) or Norouzi (2003), and PCR was used with a BIO RAD thermocycler. Cluster analysis and grouping of genotypes were performed using Jaccard similarity coefficient and UPGM method and principal component analysis (PCOA) based on distance matrix using NTSYS: pc 2.1 software. Results and Discussion. In this experiment, SSR markers were able to identify 31 alleles with a range of one to four alleles in each gene location and reproduce 355 locations. The average amplified location for 20 primer pairs was 17.75 and the range of polymorphic information content change was 0.54 to 0.75 with an average of 0.66. The range of similarity coefficient obtained from SSR markers varied from 0.35 to 0.9. In breeding programs, the varieties that have the least similarity are the best plants for crossbreeding. The cophenetic correlation coefficient was obtained based on the Jaccard similarity coefficient of 0.76. Based on the cut line, a cluster diagram was created with six subgroups at a distance of 0.46. Also, the results of principal component analysis showed that the first five components explained about 59% of the total variation between lines. With the studies conducted, five markers (SSR: 4, 10, 23, 32, and 50) were able to distinguish between 15% - 40% of plants sensitive and resistant to rhizoctonia root rot. Conclusion. According to studies conducted on the genetic diversity of different sugar beet plants using SSR markers, some plants were not included in their similar group, despite having a resistant or susceptible phenotype to root rot disease. Based on the results of this study and the results of previous research, it can be concluded that the resistance or sensitivity of sugar beet plants can be influenced by one or more specific genes and the presence or absence of these genes, does not necessarily cause genetic similarity or dissimilarity of genotypes with each other. For the final confirmation and validation markers, more sensitive and resistant samples will be tested with the selected SSR and the best marker(s) will be introduced. Introduction. Sugar beet is the main source of sugar with about 35% of the world's sugar production. It is affected by various pathogenic factors. The most important pathogens that lead to sugar beet root rot is the Rhizoctonia solani fungus, which exists in many areas of sugar beet cultivation. Given that conventional breeding methods for resistance to this disease are difficult and time-consuming, the development and identification of resistance-associated markers and the determination of the locus controlling resistance to this disease can significantly accelerate root rot resistance breeding programs and provide a new perspective for plant breeding advances. To achieve resistant cultivars, the development of markers related to resistance can help breeding programs. In this regard, the aim of this research is to identify molecular markers associated with rhizoctonia resistance genes to accelerate the screening of sugar beet breeding materials. Materials and Methods. In this study, 20 pairs of primers were used to investigate 10 susceptible and 10 resistant plants from two F2 populations in order to identify molecular markers linked to the resistance gene to rhizoctonia root rot of sugar beet. The primers were examined in terms of band pattern and the bands were scored based on their presence or absence (zero and one). DNA extraction was performed using Modified Dellaporta et al. (1983) or Norouzi (2003), and PCR was used with a BIO RAD thermocycler. Cluster analysis and grouping of genotypes were performed using Jaccard similarity coefficient and UPGM method and principal component analysis (PCOA) based on distance matrix using NTSYS: pc 2.1 software. Results and Discussion. In this experiment, SSR markers were able to identify 31 alleles with a range of one to four alleles in each gene location and reproduce 355 locations. The average amplified location for 20 primer pairs was 17.75 and the range of polymorphic information content change was 0.54 to 0.75 with an average of 0.66. The range of similarity coefficient obtained from SSR markers varied from 0.35 to 0.9. In breeding programs, the varieties that have the least similarity are the best plants for crossbreeding. The cophenetic correlation coefficient was obtained based on the Jaccard similarity coefficient of 0.76. Based on the cut line, a cluster diagram was created with six subgroups at a distance of 0.46. Also, the results of principal component analysis showed that the first five components explained about 59% of the total variation between lines. With the studies conducted, five markers (SSR: 4, 10, 23, 32, and 50) were able to distinguish between 15% - 40% of plants sensitive and resistant to rhizoctonia root rot. Conclusion. According to studies conducted on the genetic diversity of different sugar beet plants using SSR markers, some plants were not included in their similar group, despite having a resistant or susceptible phenotype to root rot disease. Based on the results of this study and the results of previous research, it can be concluded that the resistance or sensitivity of sugar beet plants can be influenced by one or more specific genes and the presence or absence of these genes, does not necessarily cause genetic similarity or dissimilarity of genotypes with each other. For the final confirmation and validation markers, more sensitive and resistant samples will be tested with the selected SSR and the best marker(s) will be introduced.

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