Abstract
Rice blast disease caused by a phytopathogenic fungus, Magnaporthe oryzae, has been considered as a major threat to global rice productivity, including Indonesia. South Tapanuli is a regency in North Sumatra, known for its intensive and significant rice production activities. A collection of 13 rice cultivars originating from the region, is claimed for its resistances against the rice blast disease based on the practices by the local farmers. Molecular screening of blast resistance (R) genes was initiated to the 13 accessions using the Polymerase Chain Reaction (PCR) targeting five blast resistance (R) genes, Pup1, Pi-37, Pi-d2, Pi-ta2, Pib and Pi-kh. Out of the 13 accessions, the Pi-d2, Pi-ta2 and Pib were detected in all cultivars, showing 100% of R gene frequency. The second dominant, Pup1 and Pi-37 gene frequencies were 76.9 and 61.5%, respectively while the least dominant, Pi-kh gene frequency was 15.4%. The number of R genes detected among cultivars was ranged between 3 to 6 genes. The genetic associations among thirteen germplasms were determined using unweighted pair group method with arithmetic mean (UPGMA) analysis. Cluster analysis revealed that the least blast-resistant cultivars: Putri Kembar, Silatian and Siganteng, were grouped into cluster 1, showing polymorphism for Pi-d2, Pi-ta2 and Pi-b. The high-resistant cultivars, Martabe-Sicondong and Sayuti, Sitolas, Pulo Raja, Pulo Pandan, Siporang and Pulo Manggis, were grouped into cluster 2 and 3, respectively. The medium blast-resistant cultivars, IR 64 and Sitampan were grouped into cluster 4, showing polymorphism for Pup1, Pi-d2, Pi-ta2 and Pi-b. These results indicated that the utilization of blast-resistant cultivars in North Tapanuli was supported by the presence of R genes.
Highlights
Rice (Oryza sativa L.) is one of the essential agricultural commodities in the world and becoming a staple food to almost all populations in the tropical region
Polymerase Chain Reaction (PCR) results of the thirteen accessions were determined for the presence of one or more different R genes (Table 3)
Pup1 rice blast resistance gene was visualized by the amplicons of 1010 bp and was detected in 10 accessions (76.9%), in exception to ‘Siganteng’, ‘Silatian’ and ‘Putri Kembar’ cultivars
Summary
Rice (Oryza sativa L.) is one of the essential agricultural commodities in the world and becoming a staple food to almost all populations in the tropical region. In Indonesia, intensive research and development have been efforted to yield a higher rice productivity annually as well as developing a stable or higher production in a dynamic environment modified by the presence of abiotic and biotic stressors (Panuju et al., 2013). Indonesia’s rice production is constantly threatened by several biotic stressors, from important pathogenic diseases to disruptive physical damages by insect pests. The substantial loss of global rice productivity impacted by the diseases, may reach 30% or equivalent to a food supply for 60 million people (Nalley et al, 2016).
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