مکان‌یابی ژن‌های کمی کنترل کننده محتوای کلروفیل در شرایط نرمال و تنش شوری در گیاهچه‌های برنج و مقایسه روش‌های مختلف مکان‌یابی qtl

شوری یک محدودیت عمده در توسعه کشت برنج می‌باشد. بهبود بخشیدن به تحمل به شوری در برنج ازنظر ژنتیکی یک مسئله بسیار مهم در برنامه‌های اصلاحی است. به‌منظور مکان یابی ژن های کنترل کننده محتوای کلروفیل، 96 لاین خالص نوترکیب برنج ایرانی حاصل تلاقی ارقام ندا × اهلمی طارم تحت تنش شوری در مرحله گیاهچه‌ای آزمایشی به‌صورت مرکب در قالب طرح کاملاً تصادفی با سه تکرار و دو شرایط کشت نرمال و تنش شوری در دانشگاه گنبد‌کاووس در سال 1395 در شرایط گیاهچه کشت شدند. مکان‌یابی ژن‌های کنترل‌کننده محتوای کلروفیل با استفاده از روش‌های مختلف مکان‌یابی شامل simmel، sim، cim، mim، pmle، icim و stsim انجام گرفت و با استفاده از هر کدام از این روش‌ها qtl‌های مشابه و متفاوتی ردیابی شد. 40 نشانگر ssr و 16 نشانگر issr (76 آلل تکثیر‌شده چند شکل)، 2 نشانگر irap (7 آلل تکثیر‌شده چند شکل) و یک نشانگر ipbs (3 آلل تکثیر‌شده چند شکل) بر روی 12 کروموزوم برنج توزیع شدند. روش icim، cim و sim در شرایط نرمال و تنش شوری بیشترین تشابه مکان‌های ژنی ردیابی شده را دارا بودند. qchl6 در شش روش مکان‌یابی در موقعیت 52 سانتی‌مورگان از کروموزوم 6 شناسایی شد. بنابراین با استفاده از qtl‌های شناسایی شده می‌توان پس از تعیین اعتبار qtlها، ژنوتیپ‌های برتر از نظر محتوای کلروفیل برای برنامه‌های انتخاب به کمک نشانگر را شناسایی کرد.

Detection of quantitative genes controlling of chlorophyll content in rice seedling under normal and salinity stress and comparison of different QTL mapping methods

Introduction Rice (Oryza sativa L.) is a major source of food and energy for more than 2.7 billion people on a daily basis and is planted on approximately onetenth of the earth’s arable land. Rice is one of the most important cereal. Salinity is the second most problem next to drought, in rice growing areas of the world. Soil salinity is a abiotic stress in crop productivity worldwide. The aim of the present study is to identify QTLs related to salt tolerance by using an Iranian rice population and Comparison of different QTL mapping methods. Materials and methods A F8 RILs population, derived from a cross between a salt tolerance Ahlemi‌ Tarom (ATM) and salt sensitive Neda (NAD) which were used in this study. The early crosss and segregated generations in the University of Gonbad Kavous were developed. The genetic material involved 96 lines were used to evaluate the salt tolerance. This experiment was conducted at the faculty of agriculture, university of GonbadKavos, in 2016 as hydroponics. The seeds were placed 50 ˚C for 3 d to break dormancy, and then germinated at 25 ˚C for 72 hours. Finally, the germinated seeds were sown in holes of the Styrofoam board with a nylon net bottom, which floated on water for 3 d, and after were transferred to float on Yoshida’s nutrient solution for 11 d. two week after sowing, the seedling were transferred to nutrient solution with electrical conductivity 6 dSm1 for 7 days, then NaCl concentration was increased to 12 dSm1 for further 7 days. This experiment was conducted in a controlled condition with 16h photoperiod, temperature of 29/21 ˚C and minimum relative humidity of 70%. The culture solution was renewed weekly and the PH was adjusted daily to 5.5 by adding either NaOH or HCL. Chlorophyll content was measured using a SPAD device. 40 SSR primer pairs, 16 ISSR markers (76 alleles), two IRAP markers (7 alleles) and one iPBS marker (3 alleles) were appropriately distributed on 12 rice chromosomes. Finally, The genes controlling the chlorophyll content located using different QTL mapping methods in clouding SIMMEL، SIM، CIM، MIM، PMLE، ICIM and STSIM. These methods detected different QTL. Results and discussion In CIMMLE method, five QTL were detected on chromosomes 3, 5, 6, 7 and 8 in normal condition, and three QTL were detected on chromosome 2 and 6 in salt stress condition. In SIM method, three QTL were identified on chromosomes 2, 3 and 8 in normal condition, and five QTL were identified on chromosomes 4, 6, 7 and 10, in salt stress conditions. In CIM method, three QTL were detected on chromosomes 2, 3 and 8, these QTLs justifying 1323% of the phenotypic change of trait, in normal condition, but under salt stress condition, six QTL were detected on chromosomes 1, 2, 6 and 7. qCHLN3, qCHLN5 and qCHLN6 were detected by MIM method in normal condition and qCHL6a and qCHL6b were detected on chromosome 6 in salt stress condition. Six QTL were detected by PMLE method in normal condition and two QTL detected on chromosomes 6 and 9 in salt stress condition. In ICIM method, three QTL were identified on chromosomes 2, 3 and 8 in normal condition, in salt stress condition were detected five QTL on chromosomes 4, 6, 7 and 10. qCHLN3, qCHLN6 and qCHLN7 were detected by STSIM method in normal condition, andqCHL6on chromosome 6 and has a LOD of 3.187 and an additive effect of 0.079. Conclusions ICIM, CIM and SIM has most closely in genetic location in normal and salt stress conditions. qCHL6 was identified in six location method at 52 cM position in chromosome 6. qCHLM3 and qCHLN8 were detected in CIM, CIM and SIM on chromosomes 3 and 8 and explaining 1822% of phenotypic variance chlorophyll content in normal condition. CIM, ICIM and SIM method were detected QTLs on chromosomes 6 and 7. Among the methods used, the CIM has the least error in estimating the original QTL effect and it can be done at any point in the genome that is covered by markers and the performance of the markers is higher in this method. Therefore, the effectiveness of using the markers introduced in this method will be higher. The results of this study can identify the better genotypes in term of chlorophyll content for marker selection programs after validation of QTLs.