Marker-assisted introgression of multiple resistance genes confers broad spectrum resistance against bacterial leaf blight and blast diseases in Putra-1 rice variety

Abstract

This experiment was conducted with the aim of introgressing multiple resistance genes against bacterial leaf blight (BLB) and blast diseases through marker-assisted backcross breeding. Two dominant (Xa4 and Xa21) and two recessive (xa5 and xa13) BLB resistance genes were introgressed into a Malaysian elite rice variety Putra-1 with genetic background of three blast resistance (Piz, Pi2 and Pi9) genes and high yielding. Eight polymorphic tightly linked functional and SSR markers were used for foreground selection of target genes. 79 polymorphic SSR markers were used in background selection. The plants were challenged at initial stage of breeding and challenged again at BC 2 F 2 with the most virulent Malaysian pathotypes of Xoo (P7.7) and Magnaporthe oryzae (P7.2) to test their resistance. Results obtained from foreground marker analysis showed that the BC 1 F 1 and BC 2 F 1 both fitted into the Mendel's single gene segregation ratio of 1:1 for both Xoo and blast resistance. At BC 2 F 2 , result obtained indicated that foreground marker segregation fitted into the expected Mendelian ratio of 1:2:1 for blast resistance only. Marker-assisted background selection revealed high percentage of recurrent parent genome recovery (95.9%). It was concluded that resistance to Xoo pathotype P7.7 in IRBB60 was neither due to two independent gene action nor epistasis but substantially due to single nuclear gene action. Also, the inheritance of blast resistance in the pyramided lines to pathotype P7.2 was also attributed to single gene action. The incorporation of four bacterial leaf blight and three blast resistance genes (Xa4+xa5+xa13+Xa21+Pi9+Pi2+Piz) in the newly developed lines provides for broad spectrum and durable resistance against the two major diseases studied.

Genetic Diversity of Selected Rice Genotypes under Water Stress Conditions

“…These markers revealed the highest PIC values and gave the same values 1.00 and the highest number of alleles ranging from 8 to 9 alleles per locus, suggesting that these markers could be used for molecular characterization of a large number of rice genotypes rather than mapping populations for drought tolerance. The results were similar to those obtained by [ 10 , 51 , 52 ].…”

“…In contrast to morphological traits, molecular markers can reveal large differences among genotypes at the DNA level, providing a more direct, reliable, and efficient tool for germplasm characterization, conservation, and management and untouched by environmental influence [ 9 ]. SSR markers can detect a high level of allelic diversity, and they have been extensively used to identify genetic variation among rice subspecies [ 10 ]. Simple sequence repeats (SSR) markers are efficient in detecting genetic polymorphisms and discriminating among genotypes from germplasms of various sources; even they can notice the finer level of variation among closely related breeding materials within the same variety [ 11 ].…”

Marker Assisted Forward Breeding to Combine Multiple Biotic-Abiotic Stress Resistance/Tolerance in Rice

“…It was also reported that Abhaya was found to be resistant against blast (blast SES score ranged from 1 to 3 with different isolates) (Sinha et al 2017) isolates. Similarly, IRBB60 was also reported to have moderately resistant reaction with blast (with blast SES score of 3) (Chukwu et al 2020). While working with BLB, the challenge appears to be more due to the presence of the number of genetically distinct virulent Xoo strains in different geographical locations (Midha et al 2017).…”

Assessment of Some Agro-Physiological Traits and Genetic Markers in Rice (Oryza sativa L.) Under Normal and Water Stress Conditions

“…Molecular markers could reveal significant differences among genotypes at the level of DNA in contrast to morphological characteristics, providing a more effective, accurate and efficient instrument for the characterization, conservation and management of germplasm and untouched by environmental influence (Singh and Sengar, 2015). SSR markers can detect a high degree of allelic diversity, and it have been widely used to identify genetic variation among rice subspecies (Chukwu et al, 2020). Simple sequence repeat (SSR) markers are successful in detecting genetic polymorphisms and distinguishing between genotypes from different sources of germplasm, they can also detect the finer level of variation within the same variety among closely related breeding materials (Lapitan et al, 2007).…”