Abstract
Rice (Oryza sativa L.), is a staple food and cash crop in many countries and studies on geneticstructure and differentiation patterns of rice land races along with the cultivated rice, provide important data for future rice breeding. Therefore, the aims of present investigation were 1-To study the genetic diversity present withinIranian rice genotypes, 2-To study genetic relatedness of these rice genotypes, and 3-To providebarcoding of the rice genotypes based on SSR molecular markers and produce data for rice varieties authentication. In total, 201 rice samples originated from 10 geographical regions of Iran were studied in this project. All rice samples underwent fragment analysis in every 64 SSR loci and different clustering and ordination methods performed. In general four major clusters were formed. Both landraces as well as rice cultivars were distributed in different clusters due to their genetic difference. STRUCTURE analysis of the studied genotypes followed by Evanno test produced the optimal number of genetic groups K = 2. The mean Nm = 13.6, for the studied genotypes indicates that a high degree of gene flow/ancestral common alleles are present in the rice genotypes studied. Mantel test indicated a significant positive association between genetic distance and geographic distance of the rice genotype studied and presence of an overall isolation by distance (IBD) model of differentiation across the geographical regions of Iran. Overall, the significant genetic difference observed between rice landraces and rice cultivars ofthe country may be used in future hybridization and breeding of rice in the country. The landracerice genotypes may contain useful genes to be transferred to the popular rice cultivars. Moreover, SSR loci that can differentiate rice genotypes are identified and can be used in rice cultivars authentication.
Highlights
Rice (Oryzasatavia) is a diploid annual grass (2n = 24) of the family Poaceae, which is an important food crop with the highest production afterNeda Sepahian, Zahra Noormohammadi, Masoud Sheidai, Hamid-Reza Zamanizadeh sugarcane and maize
Thirty-five rice seed samples were dedicated from the International Rice Research Institute (IRRI), Philippines and twenty-two parboiled rice grain samples were collected from the market (Table S1)
Grouping of the rice genotypes studied by different clustering methods produced similar results, only Ward dendrogram is presented (Fig. 1)
Summary
Though it was originated in China, nowadays has several wild and related genotypes, many landraces and cultivated forms throughout the world (Henga et al 2018). Rice plant has suffered great genetic diversity reduction (about 80%), from that of the wild ancestor during the domestication as well as local artificial selection processes. This genetic erosion in the high-yielding rice varieties, results in disease susceptibility, and the loss of suitable genes This genetic erosion in the high-yielding rice varieties, results in disease susceptibility, and the loss of suitable genes (Cuiet al. 2017)
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