تنوع ژنتيكي و گروه‌بندي ژنوتيپ‌هاي جو پاييزه از نظر ويژگي‌هاي ريشه و نشانگرهاي ISSR

Genetic Diversity and Grouping of Winter Barley Genotypes for Root Characteristics and ISSR Markers

هدف اين پژوهش بررسي تنوع ژنتيكي ميان 28 ژنوتيپ جو پاييزه با استفاده از صفات ريشه و 14 آغازگر ISSR طي دو آزمايش بود. آزمايش گلخانه‌اي در قالب طرح بلوك‌هاي كامل تصادفي با دو تكرار در گلخانه تحقيقاتي دانشگاه تبريز در سال 1388 صورت گرفت و صفات وزن خشك ريشه، حجم ريشه، وزن خشك بخش هوايي و نسبت وزن خشك ريشه به بخش هوايي اندازه‌گيري شدند. آزمايش مولكولي با 28 ژنوتيپ جو و 14 آغازگر ISSR انجام شد. تنوع معني‌داري بين ژنوتيپ‌هاي جو از نظر مشخصات ريشه مشاهده شد. ژنوتيپ‌هاي 3، 5، 9 و 20 داراي مقادير بيشتري از نظر مشخصات ريشه بودند. تجزيه خوشه‌اي به روش Ward و فاصله اقليدسي، ژنوتيپ‌ها را در چهار گروه قرار داد كه ژنوتيپ‌هاي گروه سوم از نظر كليه صفات داراي ميانگين بالاتري بودند. از 14 آغازگر ISSR مورد استفاده، 11 آغازگر الگوي نواري مناسب و قابل امتيازدهي توليد كردند. در مجموع، 559 نشانگر چند شكل با طول 80 تا 3000 جفت باز در ژنوتيپ‌هاي جو توليد شد. ميزان اطلاعات چند شكلي نشانگرها بين 116/0 تا 252/0 و شاخص نشانگر بين 528/3 تا 972/27 به‌دست‌آمد. گروه‌بندي ژنوتيپ‌هاي جو بر اساس داده‌هاي مولكولي ژنوتيپ‌ها را به چهار گروه منتسب كرد. بين نتايج گروه‌بندي بر اساس داده‌هاي مولكولي و صفات مورد مطالعه تا حدودي تطابق وجود داشت. بر مبناي بررسي ارتباط نشانگرهاي ISSR با صفات كمي، ISSRهاي 1 و 5 داراي رابطه معني‌داري با اكثر صفات بودند. به نظر مي‌رسد كه مي‌توان از نشانگرهاي ISSR مورد مطالعه در امر گزينش به كمك نشانگر در برنامه‌هاي به‌نژادي جو استفاده كرد.

Background and Objectives Determination of genetic diversity level is fundamental for identification of desirable parents to be used in different breeding programs, and molecular markers have been succssfully taken for the analysis of genetic diversity in various crops. The objective of this study was to inversitgate genetic diversity among 28 genotypes of barley using root and shoot characters and 14 ISSR primers through two separate experiments (greenhouse and molecular experiments). Materials and Methods The greenhouse experiment was carried out as randomized complete block design with two replications in the research greenhouse of Faculty of Agriculture, University of Tabriz, Iran. The traits measured in the greenhouse were root dry weight, root volume, shoot dry weight and ratio of root to shoot dry weight. The molecular experiment was conducted to study the diversity of barley genotypes using 14 ISSR primers. The polymorphic information content and marker index were calculated for each ISSR primer. Results Analysis of variance showed significant differences among the genotypes under study for all traits. According to the mean comparisons, genotypes 3, 5, 9 and 20 had higher mean in terms of all characters. The cluster analysis, based on Ward­­'s algorithm and Euclidean distance, grouped genotypes in four clusters. Group 3 had the highest mean in terms of all of the studied characters. Out of 14 ISSR primers used, 11 primers generated scorable and appropriate banding pattern. A total of 559 polymorphic bands with 80-3000 bp were produced. Polymorphic information content was estimated to be between 0.116 and 0.252 with the average of 0.187. The marker index ranged from 3.528 to 27.972 with the mean of 9.704. Classification of the studied barley genotypes was conducted by molecular data using neighbor joining algorithm based on distance coefficient of number of differences, which assigned the genotypes into four groups. There was a concordance between the grouping of genotypes based on molecular data and the characters in the greenhouse, but this concordance was not complete. Association analysis of ISSR markers with measured characteristics of barley genotypes showed that ISSR1 and ISSR5 had significant relationship with most of the root and shoot traits. Discussion Highgenetic diversity was observed among barley genotypes with respect to root and shoot traits. The results showed that ISSR primers have the ability to separate barley genotypes from each other. Also, it seems that ISSR markers under study can be used in marker assisted selection of barley genotypes in breeding programs.