گزينش به كمك نشانگر SCAR براي توليد ارقام مقاوم به فوزاريوم (Fusarium oxysporum f.sp. melonis) در طالبي

Marker assisted selection using SCAR to develop Fusarium (Fusarium oxysporum f.sp. melonis) resistant melon

طالبي محصول مهمي است كه به‌صورت گسترده در كشورهاي مناطق معتدله رشد مي‌كند. يكي از مهم‌ترين بيماري‌هاي اين گياه پژمردگي آوندي ناشي از Fusarium oxysporum f.sp. melonis (Fom) است. اين قارچ سبب ضرر و زيان‌هاي مهم عملكردي و كاهش كيفيت ميوه در طالبي در سراسر جهان مي‌شود. اصلاح ژنتيكي گياه مؤثرترين راه براي كنترل اين بيماري است. تاكنون براي اين قارچ چهار نژاد صفر، 1، 2 و 1/2 گزارش شده‌است كه نژاد 1 از نظر اقتصادي ضررهاي زيادي در كشور به‌ويژه در نيمه شمالي وارد مي‌كند. ارقام محلي مهم از جمله ساوه، ريش بابا و تيل طرق به‌نژاد 1 حساس هستند. در اين مطالعه ژن مقاومت از يك رقم خارجي به‌نام ايزابل به ارقام حساس ياده شده با كمك گزينش به كمك نشانگر انتقال داده شد. غربال گياهان در نسل اول و دوم تلاقي برگشتي با روش مايه زني گياه‌چه‌ها انجام گرفت. تك ژن غالب Fom-2 باعث ايجاد مقاومت در برابر نژاد صفر و 1 مي-شود. اين ژن توالي‌يابي شده و تفاوت‌هاي موجود در توالي آلل‌هاي مقاوم و حساس شناسايي شده-است. به‌منظور تاييد گياهان مقاوم در نسل دوم تلاقي برگشتي پس از غربال با روش مايه زني، از نشانگر SCAR مبتني بر تفاوت توالي استفاده شد. مقاومت بيش‌تر گياهان حاصل از غربال با روش مايه‌زني با روش مولكولي نيز تاييد شد اگر چه تعدادي گياه حساس شناسايي شدند كه بيانگر نقص در روش مايه-زني و اعتبار بيش‌تر روش مولكولي در تعيين ژنوتيپ گياهان بود. گياهان تاييد شده براي توليد نسل BC3F1 با سه والد تكراري تلاقي برگشتي داده شدند. با توجه به عملكرد و كيفيت والد بخشنده و نتايج ارزيابي نسل BC2F1 به‌نظر مي‌رسد با خودگشني گياهان BC3F1 بتوان ارقام خالص مقاوم را معرفي كرد.

Melon is an important crop cultivated in moderate climate regions of the world. One of the most important diseases of this plant is vascular wilt caused by Fusarium oxysporum f.sp. melonis (Fom). The infection of farm with this pathogen can result in huge loss of yield and fruit quality of melon around the world. Genetic improvement for resistance is the best way of control of this disease. Up to now four races of 0, 1, 2 and 1,2 have been reported among which race 1 is more versatile and dangerous than other races especially at the north part of the country. Land races such as Saveh, Rish-baba and Tile-torogh are susceptible to this race. In this research the resistance gene was transferred from Isabelle, a resistant cultivar to susceptible varieties via marker assisted backcrossing. The screening of plants in BC1F1 and BC2F1 generations was carried out using artificial inoculation. Single dominant gene of Fom-2 induces resistance toward race 0 and 1. This gene has been sequenced and there are differences between susceptible and resistant allele. In order to verify the resistant plants survived after artificial inoculation in BC2F1, the plants were genotyped by SCAR marker. The resistance of most plants was verified however there were some susceptible plants among them implying the shortcomings of artificial inoculation method and more strength of molecular method. The verified plants were crossed to recurrent parents to produce BC3F1 generation. Considering acceptable yield and fruit quality of donor cultivar and evaluation results of BC2F1 it seems that no more back crossing is needed and with the selfing of BC3F1 plants new homozygote resistant varieties will be produced. The screening of plants in BC1F1 and BC2F1 generations was carried out using artificial inoculation. Single dominant gene of Fom-2 induces resistance toward race 0 and 1. This gene has been sequenced and there are differences between susceptible and resistant allele. In order to verify the resistant plants survived after artificial inoculation in BC2F1, the plants were genotyped by SCAR marker. The resistance of most plants was verified however there were some susceptible plants among them implying the shortcomings of artificial inoculation method and more strength of molecular method. The verified plants were crossed to recurrent parents to produce BC3F1 generation. Considering acceptable yield and fruit quality of donor cultivar and evaluation results of BC2F1 it seems that no more back crossing is needed and with the selfing of BC3F1 plants new homozygote resistant varieties will be produced.