Rice Science

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Twenty-Five Years of Pi54: Discovery, Deployment, and Its Role in Silent Revolution in Rice Breeding

  1. Indian Council of Agricultural Research (ICAR)-National Institute for Plant Biotechnology, Pusa Campus, New Delhi 110012, India; ICAR-Central Rice Research Institute, Cuttack 753006, India; Chaudhary Sarwan Kumar Himachal Pradesh Agricultural University, Palampur 176062, India; ICAR-National Institute for Research on Commercial Agriculture, Rajahmundry 533105, India; ICAR-Indian Institute of Pulses Research, Kanpur 208024, India; Central University of Haryana, Mahendergarh 123031, India
  • Contact: Tilak Raj SHARMA
  • Supported by:
    Tilak Raj Sharma is thankful to the Indian Council of Agricultural Research (ICAR), World Bank-National Agricultural Innovation Project, Department of Biotechnology, Government of India, and JC Bose National Fellowship of the Department of Science and Technology, Government of India for the funding support for more than 25 years of research on the M. oryzae-rice pathosystem. T. R. Sharma is also thankful to Professor B. M. Singh, former Dean of the College of Agriculture, Himachal Pradesh Agricultural University, Palampur, India under whose guidance the project on identification of rice blast resistance sources was started in 1996 and other collaborators in the country for their useful inputs. Authors also thank Dr. Shikari, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir, India, for providing photos of Pi54 deployed and control rice varieties exposed to blast disease under field conditions.

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Abstract: Rice blast, caused by the fungal pathogen Magnaporthe oryzae, remains a major constraint to rice productivity. To date, more than 100 blast resistance (R) genes have been mapped and about 50 of them, including alleles and orthologues, have been cloned and functionally characterized. Among these, Pi54, originally identified in the Tetep rice line, encodes a leucine-rich repeat protein with a small zinc finger domain, conferring durable, broad-spectrum resistance against diverse M. oryzae isolates from different rice-growing regions globally. Expanding the allelic base, Pi54 orthologues, Pi54rh and Pi54of, have been cloned from wild rice species, and allelic diversity has been explored in rice landraces. The rice-M. oryzae system represents a classic gene-for-gene interaction. To validate this hypothesis, we sequenced the complete genome of an M. oryzae isolate avirulent on Pi54 and cloned the AvrPi54 gene. The hypersensitive response obtained from the direct interaction between Pi54 and AvrPi54 proteins confirmed the gene-for-gene relationship. Translationally, the Pi54 gene, identified, cloned, and characterized by our group, has been introgressed into over 40 rice mega-varieties using marker-assisted selection in India and abroad, exemplifying the integration of molecular genetics into breeding pipelines. This review synthesizes current insights into the molecular, functional, and applied aspects of Pi54-mediated blast resistance, highlighting its pivotal role in the ongoing ‘Silent Revolution’ in rice breeding.

Key words: rice blast, Magnaporthe oryzae, map-based cloning, Pi54 gene, AvrPi54 gene, transcriptomics, inducible promoter