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

Abstract

Bacterial leaf blight (BLB) and blast are among the most destructive diseases of rice. In order to develop new varieties that can resist various races of the pathogens Xanthomonas oryzae pv. oryzae (Xoo) and Magnaporthe oryzae, which cause these two diseases, respectively, it is important to identify suitable markers and a marker-aided selection strategy. Seventeen foreground microsatellites associated with resistance against BLB and blast were screened for polymorphism for possible adoption in a breeding program for resistant cultivar development. A total of 472 background simple sequence repeats (SSRs) were also screened for polymorphism in order to recover the recurrent parent genome. All 72 F₁ progenies were also analysed with the 17 foreground and 472 background markers in comparison to the alleles of their parents. The markers were validated using 218 BC₂F₂ plants. The result revealed six tightly linked polymorphic foreground markers (Xa21FR, pTA248, Xa13prom, MP, RM21 and RM13) associated with resistance against Xoo pathotype P7.7 and two microsatellites (RM6836 and RM8225) associated with resistance against blast pathotype P7.2. A total of 79 polymorphic background markers were identified for recovering the recurrent parent genome. The result also showed that the markers had goodness of fit (blast resistance) to 1:2:1 ratio for single gene model in BC₂F₂ progenies. These genetically confirmed microsatellite markers were recommended for use in marker-assisted backcross breeding and other marker-assisted selection of BLB and blast resistance genes in order to develop varieties with durable and broad spectrum resistance against the two major rice diseases.

Keywords:

• Polymorphism
• SSRs
• resistance gene
• molecular marker
• Xanthomonas
• Magnaporthe oryzae

Acknowledgments

The authors are grateful to the technical staff and technologists in the molecular laboratory of Institute of Tropical Agriculture and Food Security, Universiti Putra Malaysia, especially Mrs. Nooraishah Abd Aziz for the technical supports while the work lasted. All colleagues from various universities whose research output were useful are well appreciated.

Disclosure statement

The authors declare no conflict of interest.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article. The supplementary materials and other raw data generated at Molecular Laboratory of the Institute of Tropical Agriculture and Food Security (ITAFoS), Universiti Putra Malaysia, are available from the corresponding author (MYR – [email protected]) on request.

Additional information

Funding

This study was supported by the Higher Institution Centre of Excellence (HiCoE) Research Grant (Vot number 6369105), Ministry of Education, Malaysia. We appreciate the funding for research activities on rice crop improvement for biotic resistance.