Evaluation of Local Black Glutinous Rice Germplasm of Vietnam for Resistance to Bacterial Leaf Blight Disease

Abstract

    Most rice growing areas frequently encounter the bacterial leaf blight, Xanthomonas oryzae pv oryzae (Xoo). To prevent the disease, development of resistant varieties is considered to be the most economical and environmentally safe solution. In this study, three PCR-based markers, Npb181, RM122, and P3, were used for the identification of the genes Xa4, xa5, and Xa7, respectively, from 56 local black glutinous rice accessions of Vietnam. Phenotypic screening of the accessions for resistance to 10 Xoo strains of North Vietnam, along with IRBB4, IRBB5, and IRBB7 as resistant controls and IR24 as a susceptible control were carried out in the 2016 Autumn season. 19 accessions containing the resistant genes were found, of these, 6 accessions carried Xa4 gene, 6 accessions carried xa5 gene, and 11 accessions carried Xa7 gene. Three accessions carried two resistance genes, viz. Nep do (Xa4 and Xa7), Pau cam (xa5 and Xa7), and Pe lon cam (Xa4 and xa5). Accessions with xa5 and Xa7 alone or with a combination of two genes (Xa4 and xa5, Xa4 and Xa7, or xa5 and Xa7) were resistantto 8-9 Xoo strains (8-9R/0M/1-2S). Accessions containing Xa4 showed resistance to 5-6 strains of Xoo (5-6R/0M/4-5S). Xoo strain No1 (HUA01043) showed the lowest virulence, infecting only 14 accessions (42R/4M/14S). Strains No3 (HUA 0020131-2), No4 (HUA202361), No5 (HUA20212), and No8 (HUA 020083) showed highest virulence, and they each infected more than 40 accessions with 19R/0M/41S, 20R/0M/40S, 16R/4M/40S, and 20R/0M/40S, respectively. These strains can even infect some accessions containing effective resistant genes (Xa4 or Xa7).