Molecular Screening of Blast Resistance Gene Pi2 in Indian Rice Landraces (Oryza sativa L.) and its Verification by Virulence Analysis

The Pi2 gene is a member of a multigene family which confers resistance to strains of blast pathogen Magnaporthe oryzae. The gene encodes a typical NBS-LRR type protein which confers broad spectrum resistance to a wide range of races of blast pathogen prevalent in eastern India. In the present study, the presence of Pi2 gene in 61 landraces was determined using a pair of primers NBS2P3 and NBS2R followed by restriction digestion and the results were further confirmed by pathotyping using M. oryzae isolates avirulent for Pi2 gene. The Pi2 gene was found in four rice landraces from Sikkim and one landrace from Jharkhand though the latter was susceptible to the isolate bearing corresponding avirulence gene. Presence of Pi2 gene in independent indica landraces from the eastern Indian region suggested that the gene might have originated and evolved in indica rice and exist in different allelic forms in blast endemic zones of eastern India. The present study not only identifies the presence of Pi2 gene in landraces but also demonstrates the usefulness of molecular markers and virulence analyses for rapid identification of resistant genes in rice landraces. These characterized landraces can be used for genetic studies and marker assisted breeding for improving blast resistance in rice. © 2015, The National Academy of Sciences, India.