Investigation of Genetic Nature of Rice Mutant Lines using Morphological Traits and SSR Markers Linked with Rf Gene

Yield of hybrid cultivars is 20 to 30% higher than conventional cultivars. On the other hand, the most important challenge for hybrid breeders, especially in Iran, is the selection of parental genotypes that have fertility restorer genes and ultimately lead to heterosis.

The present study was performed by evaluating the morphological traits of 19 rice genotypes and the linked of three SSR molecular primers related to Rf3 and Rf4 genes. These genotypes were planted in 2019 in the research farm of Genetics and Agricultural Biotechnology Institute of Tabarestan in a randomized complete block design with three replications. Quantitative and agronomic traits, especially paddy yield, were evaluated. DNA extraction was performed by CTAP method with modification from leaf samples. Three SSR markers linked with two major RF3 genes including RM490 and RM 3148 markers and RF4 gene linked with RM171 marker were used to identify fertility restorer genes in rice.

The results of comparing the mean of rice genotypes showed that P15-6 genotype with 118.33 was the earliest and all foreign genotypes with a maturity of 150 days were the latest. The highest yield of genotypes (above 700 g / m2) is related to Neda genotypes, IR 86403-5-5-2-1-1-1-1-1-1R, P15-6, P12-5-3-3-2- 2-1, P12-5-3-3-2-1-1 and P8-7-2-1-4-2-1-1, which due to the number of fertile tiller, the number of fertile panicle, 1000-seed weight and panicle fertility has been high. In the results of cluster analysis, parental cultivars were divided into three groups: in the first group (medium yield, long cluster length, high number of full seeds, and long grain length) the Jelodar cultivar, in the second group (maximum cluster fertility, 1000-seed weight and high paddy yield) Neda cultivar along with four other lines and all foreign cultivars are in the third group (late, short grain length and high grain density). Principal component analysis divided the studied traits into four main components with eigenvalues ​​above one, which in total explained 82.61% of the data changes, which these four components are more valuable and express the relationship between the traits. In total, the band pattern of three markers showed that IR 68078-15-2-1-2-2-R, IR65622-151-1-2-2-2-R and NSIC RC434 genotypes had fertility restorer genes.

Summary of all 3 SSR markers showed that genotypes P9-7-1-1-1, P11-6-2-1-1-1, P14-1 and P15-2 with two markers RM3148, RM490, have Rf3 gene and haven’t Rf4 genes and the reason that some genotypes have been identified as Rf gene with RM3148 marker but not detected with RM490 marker may be due to crossover between the desired gene and marker, so genotypes with fertility restorer gene are fertility restorer lines and can be used in hybrid rice program.