Introgression of broad-spectrum blast resistance gene(s) into cultivated rice (Oryza sativa ssp indica) from wild rice O. rufipogon

• Published in: Current science (Bangalore) Vol. 92; no. 2; pp. 225 - 230
• Main Authors: Ram, T., Majumder, N. D., Mishra, B., Ansari, M. M., Padmavathi, G.
• Format: Journal Article
• Language: English
• Published: Current Science Association 25.01.2007
• Subjects: Biological resistance; Blasts; Disease resistance; Genetic screening; Magnaporthe grisea; Medical genetics; Oryza rufipogon; Oryza sativa; Pathogens; Plants; RESEARCH COMMUNICATIONS; Rice; Salinity; Wild rice
• ISSN: 0011-3891

Rice blast disease caused by Magnaporthe grisea (Hebert) Barr, is one of the major diseases of the crop. Host specificity as well as genetic instability of rice blast fungus is the major cause for the breakdown of resistance in many varieties over a period of time. Here we report the introgression of broad-spectrum blast resistance gene(s) from Oryza rufipogon into a cultivated rice variety. An accession (Coll-4) of O. rufipogon, highly resistant to blast, was crossed with a susceptible line B 32-Sel-4 and the F₁ was top-crossed with another susceptible line B 29-6. The F₂ population of the three-way cross was screened for blast and salinity tolerance. Twenty selected plants, each with blast resistance and salinity tolerance, were intermated. The process of intermating was repeated in the F₂ progenies derived from the first intermated populations. After two cycles of intermating, pedigree selections in the resulting segregating generations were followed under saline conditions. The 42 introgression lines (F₅ generation) were screened for blast reaction under artificial inoculation. Eight lines were observed to be immune, 20 resistant and six lines moderately resistant to an isolate of blast isolated in Andamans. The remaining eight lines, the two indica rice parents and check CO39 were susceptible. Two promising lines with higher yield potential were evaluated in multilocation trials (AICRIP) during 1999, 2000 and 2001 at 17 hotspot locations for blast infection. The culture B 90-15 (IET 15420) showed resistance reaction against 14 isolates and moderate resistance against another two isolates of blast indicating the introgression of a broad spectrum of resistance to blast from O. rufipogon.