Identification of gene locations affecting germination components in the Iranian recombinant inbred lines of rice ( Oryza sativa L.) under different drought and salinity stresses

Introduction Rice (Oryza sativa L.) is one of the most important crops in the world, providing food to more than 3 billion people in the world, and is grown in about one-third of the world's agricultural land. Osmotic stress (such as drought stress) is a serious limiting factor to rice production and yield stability, worldwide. Therefore, this study was conducted to locate QTLs associated with germination stress and determine the contribution of each QTL to phenotypic variation of traits. Materials and method The plant material used in the present study was 74 lines from the F8 recombinant inbred lines of Neda × Ahlami Tarom cultivars that investigated at University of Gonbad Kavous in 2017. Factorial experiment was conducted in a completely randomized design with 9 cm diameter petri dishes with 2 replications. 100 healthy seeds were selected from 74 populations of F8, which were the result of the collision between Ahlami Tarom and Neda. The seeds were washed with 2% sodium hypochlorite solution for 10 minutes and then washed with distilled water three times. The seeds were applied to sterilized sterile filter paper and mannitol, NaCl and polyethylene glycol treatments were applied. Petri dishes were placed inside the germinator at 25 ° C and 70% moisture and darkness for one week. The number of germinated seeds for each of the lines was counted in 24, 48, 72, 96, 120, 144, 168 hours after being placed in Petri Dish, and 14 days after the culturing, the root length, The length of the stalk and the length of the coleoptile were measured using caliper and millimeters. The linkage map was based on 40 SSR markers, 16 ISSR markers (with 76 polymorph alleles), two IRAP markers (7 polymorph alleles) and an iPBS marker (with 3 polymorph alleles) on 74 F8 population attributed the markers to 12 groups with a map length of 1491 cM and a distance between flanked markers of 13.07 cM. Results and discussion Under normal conditions, nine genetic locations were detected. For the root length of five genetic locations, three, five (two cases), six and seven chromosomes were identified and four gene locations were identified for stem length, located on chromosomes 1, 5 (two cases) and 7 . qPLNO-1 and qPLNO-5b were able to justify 11.46% and 12.25% of the phenotypic variance, respectively. Two genetic locations were detected in mannitol for cholectile length on chromosome 6. For the root length of the seven QTLs, they were located on chromosomes 3, 4, 6 and 7. For stem length, four gene locations were detected on chromosomes 4 and 6, which justified 8 to 11 percent of the phenotypic variation of the trait. Two genetic locations for the root length were detected on chromosomes 5 and 8, while qRASA-8 was able to justify 14.9% of phenotypic changes in the trait. Six stroke locations were detected for stem length, which were located on chromosomes 5 (three cases), 7 (two cases) and 8, respectively 8.8, 9.5, 11.25, 9.8, 13.6% and 15.7% of the phenotypic changes justify the attribute. In the drought stress condition of polyethylene glycol, a gene site was detected for germination percentage on chromosome 2 and at 78 centimeters from the beginning of the chromosome, which justifies 10.3% of the phenotypic variation of the trait. Conclusion Under normal conditions, five gene locations were detected for root length and four gene locations for stem length. For the root length, nine genetic locations were detected and for 11 stroke locations for stem length. Under stress conditions, mannitol was detected 13 gene locations, two QTLs for coleoptile, seven QTL for root length, and four QTL for stem length. Under salinity stress conditions, two genetic locations were detected for root length-six and six gene locations for stem length. Under stress conditions from polyethylene glycol, a gene site was detected for germination percentage on chromosome 2. qCLMA-6a, aRAMA-6b and qPLMA-6b on chromosome 6 and at 52 centimeters. In normal conditions qRANO-5a for root length and qPLNO-5a for stem length at 52 cm from the beginning of chromosome 5 and had common positions among RM49 and RM39 markers. These QTLs, after determining the credibility of a suitable candidate for selection programs, help markers in the population of Iranian recombinant lines of rice.