بررسي اكوتيپ هاي يونجه زراعي با استفاده از نشانگرهاي ايزوزيمي

Study of alfalfa crops by using isozyme markers

سابقه و هدف: يونجه با دارا بودن ساختار ژنتيكي (32=x4=n2) اتوتتراپلوئيدي و دگرگشني، تنوع ژنتيكي بالاي دارد. در واقع تنوع ژنتيكي پيش نياز گزينش در برنامه هاي به نژادي براي بهبود صفات، توليد ارقام جديد و سازگار مي باشد. . نشانگرهاي آنزيمي نشان دهنده اين هستند كه مي توان از الگوي وراثت تتراسوميكي براي آناليز تنوع ژنتيكي استفاده كرد. هدف از اين پژوهش تعيين ميزان تنوع ژنتيكي و گروه بندي جمعيت هاي يونجه مورد مطالعه بر اساس وجود و عدم وجود نوار آنزيمي است. مواد و روش ها: در اين پژوهش تنوع ژنتيكي 12 خانواده ناتني يونجه با استفاده از الكتروفورز آنزيمي مورد مطالعه قرار گرفت. تعداد 35 بوته از هر خانواده در گلدان هاي مجزا در ايستگاه تحقيقاتي دانشكده كشاورزي دانشگاه تبريز كشت شدند و مورد تجزيه آنزيمي (روبيسكو، سوپراكسيد ديسموتاز، استراز و پراكسيداز) قرار گرفتند. يافته ها: از نظر نشانگرهاي آنزيمي، آنزيم هاي سوپراكسيد ديسموتاز و روبيسكو هر كدام يك نوار تك شكل در همه خانواده ها نشان دادند و آنزيم استراز و پراكسيداز در دو ناحيه واجد نوارهاي چند شكل بودند. داده هاي به دست آمده بر اساس وجود و عدم وجود نوار آنزيمي (0 و 1) در 11 نوار ايزوزيمي چند شكل مورد تجزيه و تحليل قرار گرفتند. تفسير ايزوزيمي حاكي از تنوع بالاي درون خانواده ها و پايين بودن بين خانواده ها بود. ميزان متوسط هتروزيگوسي 0/289 برآورد شد. فاصله ژنتيكي ني در تفسير ايزوزيمي كم و بين 0/248 تا 0/373 بود. تجزيه خوشه اي بر اساس ضريب شباهت ژاكارد و به روش UPGMA خانواده ها را به دو گروه تقسيم نمود به طوري كه 11 خانواده ناتني يونجه در يك گروه و تنها خانواده ناتني چالشته در گروه ديگر قرار گرفت. نتيجه گيري: به نظر مي رسد كه مي توان در صورت تاييد پايداري نشانگرهاي ايزوزيمي مورد مطالعه، از آن ها در تحقيقات آينده براي استفاده در برنامه هاي اصلاحي يونجه استفاده كرد.

Background and objectives: Alfalfa with a genetic constitution of 2n=4x=32 and autotetraploid with allogamous fertilization has more genetic diversity. In fact, genetic diversity is critical for breeding selection programs to improve trait, generate new adapted cultivars. The enzymatic markers showing tetrasomic inheritance patterns can be used to perform genetic diversity analysis. The aim of this study was to determine genetic variations levels and clustering based on enzymatic band (0 and 1) in alfalfa populations. Materials and methods: Genetic diversity of 12 alfalfa half-sib families was studied by use enzymatic electrophoresis (rubisco, superoxide dismutase, esterase and peroxidase). 35 individuals of each variety, were investigated in the Agricultural Research Station of University of Tabriz. Results: For enzyme markers rubisco and superoxide dismutase isozymes showed only one monomorphic band in all populations, but esterase and peroxidase enzymes had polymorphic bands. The resulting data based on presence and absence of enzymatic band (0 and 1) for 11 polymorphic isozymic bands were analyzed. Isozymic analysis showed that there were high levels of intra-family and low level of inter-family diversity. Average heterozygosity, as an index of within-population genetic diversity, was 0.289. Nei’s genetic distances among families were low (0.002 to 0.059). Dendrogram was constructed via the Jaccard similarity coefficient and UPGMA method, that lead to the classification of the alfalfa populations in two groups, with 11 families in one group and only Chaleshte half-sib in the other group were located that were conform the pervious conclusion. Conclusion: It might be possible to use these enzymes as markers to select alfalfa genotypes in the early breeding stages after the stability of markers were verified in other experiments. Background and objectives: Alfalfa with a genetic constitution of 2n=4x=32 and autotetraploid with allogamous fertilization has more genetic diversity. In fact, genetic diversity is critical for breeding selection programs to improve trait, generate new adapted cultivars. The enzymatic markers showing tetrasomic inheritance patterns can be used to perform genetic diversity analysis. The aim of this study was to determine genetic variations levels and clustering based on enzymatic band (0 and 1) in alfalfa populations. Materials and methods: Genetic diversity of 12 alfalfa half-sib families was studied by use enzymatic electrophoresis (rubisco, superoxide dismutase, esterase and peroxidase). 35 individuals of each variety, were investigated in the Agricultural Research Station of University of Tabriz. Results: For enzyme markers rubisco and superoxide dismutase isozymes showed only one monomorphic band in all populations, but esterase and peroxidase enzymes had polymorphic bands. The resulting data based on presence and absence of enzymatic band (0 and 1) for 11 polymorphic isozymic bands were analyzed. Isozymic analysis showed that there were high levels of intra-family and low level of inter-family diversity. Average heterozygosity, as an index of within-population genetic diversity, was 0.289. Nei’s genetic distances among families were low (0.002 to 0.059). Dendrogram was constructed via the Jaccard similarity coefficient and UPGMA method, that lead to the classification of the alfalfa populations in two groups, with 11 families in one group and only Chaleshte half-sib in the other group were located that were conform the pervious conclusion. Conclusion: It might be possible to use these enzymes as markers to select alfalfa genotypes in the early breeding stages after the stability of markers were verified in other experiments.