Molecular identification of blast resistance genes in rice genotypes using gene-specific markers

Abstract

Molecular identification of major blast resistance (R ) genes in rice was performed in a group of 10 rice (Oryza sativa) genotypes from Egypt and Saudi Arabia using six DNA markers (T8042, NSB, YL153/YL154, RM3843, RM3330, and z4794) belonging to three classes: single-nucleotide polymorphisms (SNPs), simple sequence repeats (SSRs), and insertion-deletions (InDels). The markers were chosen based on their linkage to six major R genes (Pit, Pib, Pi39 (t), Pi40 (t), Piz/Piz-t, and Pita /Pita2 ). The studied markers showed low allelic diversity, with the number of alleles identified in a single genotype ranging between two and nine alleles. The Egyptian genotype Eg-N-7 had two alleles of the Pi40 (t) gene, while the Saudi Arabian genotype Al-Ahsa1 had nine alleles that belonged to the seven R genes. The studied genotypes were also assessed for 19 agro-morphological traits.Analysis of variance of the studied traits showed significant differences among the genotypes. The putative associations between molecular markers and the agro-morphological traits were examined using associationmapping approach by employing the unified mixed model. Eight significant marker-trait associations were detected for eight agro-morphological traits (plant height, panicle length, sterility percentage, grain width, grain shape, elongation percentage, gelatinization temperature, and days to maturity). The phenotypic variance shown by each marker ranged between 43% and 65%. The findings of the current study will assist in identifying possible blast resistance genotypes for future rice breeding programs. Additionally, the results highlight the possible dual usage of specific markers in genotypic screening as well as in determining marker-trait associations.

Genetic diversity Analysis using molecular markers of some rice varieties for Physiological, biochemical and yield Traits under water deficit condition

“…The relatively high PIC values observed in this investigation demonstrated the informativeness and discriminative capacity of both markers system. The average PIC value obtained in this study was comparable to that found by Al-daej et al, using ISSR, and by Patidar et al using SCoT markers in rice germplasm 71,78 .…”

“…However, ISSR has randomly ampli ed markers, whereas SCoT is gene-targeted marker 69 . ISSR and SCoT markers have shown usefulness in genetic diversity studies due to their high repeatability and e ciency in detecting polymorphism [70][71][72][73] . The results showed that the both molecular markers exhibited comparable genetic diversity values but a higher level of polymorphism was represented by ISSR.…”

Conventional Breeding and Molecular Markers for Blast Disease Resistance in Rice (Oryza sativa L.)

“…This indicated that the resistance was transferred from resistant varieties that carried one major gene for resistance to blast disease. These results were in agreement with those of [11,16]. Note: 1 = positive band for expected size, 0 = negative band for expected size.…”

“…Whereas, Sakha 105 and Sakha 103 were resistant and the results showed the presence of Pik-s gene in those two varieties, explaining that the action of this gene is through its presence in genetic groups or that it works in complementary genes. Some of these genes were also found to be highly effective against rice blast either under Egyptian conditions [15,16] or under Chinese conditions [18].…”

“…Therefore, the identification of blast resistance genes in the cross-parents is very important to transfer the resistance trait and accumulating many different resistance genes in a new variety, which can produce durable resistance. The molecular marker technology was used to identify and confirm the blast resistance genes and detect the chromosomal regions associated with such characters [15,16]. Many different molecular markers have been used, such as microsatellite or simple sequence repeat (SSR), inter-simple sequence repeat (ISSR), intron-exon splice junction (ISJ), Single Nucleotide Polymorphism (SNP), Sequence Tagged Microsatellites (STMS) and Sequence Tagged Sites (STS) to identify blast resistance genes [17][18][19].…”