APPRAISAL OF RESISTANT GENES AND GENE PYRAMID LINES OF RICE AGAINST INDIGENOUS PATHOTYPES OF Xanthomonas oryzae pv. oryzae IN PUNJAB, PAKISTAN

Bacterial blight (BB) caused by X. oryzae pv. oryzae is a destructive disease of rice and causes 30-50% losses to rice depending on the outbreak. Development BB resistant rice varieties have long been considered as one of the most effective approach to control the disease. However, the durability of host resistance is breaking down due to the change of pathotypes of X. oryzae pv. oryzae globally. Pathotypic analyses of 239 X. oryzae pv. oryzae Bangladeshi isolates on Near Isogenic Lines (NILs) containing resistance (R) gene (s) revealed the existence of eight pathotypes of X. oryzae pv. oryzae. Among eight pathotypes, pathotypes IV and V were considered as major comprising maximum number of isolates, (30.13% and 23.01%, respectively), whereas pathotype VIII considered as minor consisting only 2.51% of total isolates. Pathotype, I showed highest virulence or aggressiveness compatible with all NILs, whereas pathotype VIII exhibited lowest virulence to these NILs. Bacterial blight resistant genes viz. Xa1 (75.00%), Xa11 (62.50%) and Xa21 (50.00%) showed resistance to most of the pathotypes while Xa4 performed worst as compared to all others R-genes. In pyramid lines, IRBBB63 (Xa5+Xa7+Xa13) and IRBB57 (Xa5+Xa7 +Xa21) showed resistance reaction and IRBB61 (Xa4+Xa5+Xa7), IRBB60 (Xa4+Xa5+Xa13+Xa21), IRBB54 (Xa5+Xa21), and IRBB53 (Xa4+Xa21) showed susceptible reaction to X. oryzae pv. oryzae pathotypes. These results collectively indicated the deployment of Xa1, Xa11, Xa4, Xa5, Xa7, Xa13 and Xa21 either alone or in combination against BB would be a best choice for the development of BB resistant rice varieties in Bangladesh.

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

Vietnam Journal of Agricultural Sciences ◽

10.31817/vjas.2018.1.3.05 ◽

2019 ◽

Vol 1 (3) ◽

pp. 240-248

Author(s):

Tung Hoang ◽

Ton Huu Phan ◽

Hai Van Tong ◽

Trung Nam Tran

Keyword(s):

Leaf Blight ◽

Xanthomonas Oryzae ◽

Bacterial Leaf Blight ◽

Resistant Genes ◽

Glutinous Rice ◽

Resistant Varieties ◽

Environmentally Safe ◽

Susceptible Control ◽

Blight Disease ◽

North Vietnam

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).

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