Marker-Assisted Introgression of Multiple Resistance Genes Confers Broad Spectrum Resistance against Bacterial Leaf Blight and Blast Diseases in PUTRA-1 Rice Variety

Abstract

Bacterial leaf blight caused by Xanthomonas oryzae pv oryzae (Xoo) and blast caused by Magnaporthe oryzae are major diseases responsible for significant yield loss in rice production across all rice growing regions. Host plant resistance has been advocated as a sustainable means of guarding against the diseases. This experiment was conducted with the aim to introgress multiple resistance genes against bacterial leaf blight and blast diseases through marker-assisted backcross breeding. Two dominant (Xa4 and Xa21) and two recessive (xa5 and xa13) Xoo resistance genes were introgressed into a high yielding Malaysian rice variety Putra-1 with genetic background of three blast resistance (Piz, Pi2 and Pi9) genes. Eight polymorphic tightly linked functional and SSR markers were used for foreground selection of target genes. Seventy nine polymorphic SSR markers were used in background selection. The plants were challenged at initial stage of breeding and challenged again at BC2F2 with the most virulent Malaysian pathotypes of Xoo (P7.7) and Magnaporthe oryzae (P7.2) to test their resistance. Results obtained from foreground marker segregation analysis at BC1F1 and BC2F1 showed that the marker polymorphism both fitted into the Mendel’s single gene segregation ratio of 1:1 for both Xoo and blast resistance. At BC2F2, results indicated that foreground marker polymorphism 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 the inheritance of blast resistance in the introgressed lines was mainly due to single gene action while the inheritance of Xoo resistance was substantially due to single nuclear 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 would provide for broad spectrum and durable resistance against the two major diseases studied.

Genetic analysis of microsatellites associated with resistance against bacterial leaf blight and blast diseases of rice (Oryza sativa L.)

“…The BC 2 F 2 population showed resistance response against BLB infection. The present findings were in agreement with Chukwu et al [10], who found both IRBB60 and BC 2 F 2 populations to be resistant to Xoo pathotype P7.7 in their studies that involved markerassisted introgression of multiple resistance genes against bacterial leaf blight and blast diseases in Putra-1 rice variety. In the case of blast disease, Putra-1 showed no symptoms of blast.…”

“…The F 1 seeds were later used to develop BC 1 F 1 , BC 2 F 1 and BC 2 F 2 populations between February 2018 and July 2019 and evaluated in field conditions. A cross made between MR219 Â Pongsu Seribu 1 [9,10] at ITAFoS led to the development of Putra-1 rice variety, while IRBB60 is an International Rice Research Institute (IRRI) variety. Putra-1 has a characteristic high yield and resistance to blast with inherent Piz, Pi2 and Pi9 R-genes but is susceptible to BLB infection.…”

Assessment of Agro-Morphologic Performance, Genetic Parameters and Clustering Pattern of Newly Developed Blast Resistant Rice Lines Tested in Four Environments

“…The Euclidean distances amidst the 19 improved genotypes evaluated were observed by using the standardized morphologic data to construct an UPGMA dendrogram. The variance components were also determined from the expected mean square using proc varcomp with restricted maximum likelihood (REML) method in SAS [10,27]. However, phenotypic variance was calculated using the formula (Equation 1):…”

“…One of the significant factors that is seriously threatening high production of rice is blast disease caused by the fungal pathogen Magnaporthe oryzae [10][11][12]. Blast disease accounted for 10%-20% yield loss in susceptible varieties and can be more than 80% in severe conditions [13].…”

Recovery of Recurrent Parent Genome in a Marker-Assisted Backcrossing Against Rice Blast and Blight Infections Using Functional Markers and SSRs

“…The F 1 hybrid was developed from a cross between Putra-1 and IRBB60 ( Figure 6 ). Putra-1 had inherent Pi9, Pi2 and Piz blast R-genes, while IRBB60 is an IRRI variety with four Xoo R-genes, namely, Xa21 , Xa4 , xa13 and xa5 [ 40 ]. Putra-1 served as female/recipient, and subsequently, the recurrent parent during hybridization and backcrossing, while IRBB60 served as the male parent (donor) during hybridization only, which led to the development of F 1 plants.…”