Rice Stem Rot Caused by Nakataea oryzae: An Overview of Pathogen Biology, Variability, Host Resistance and Disease Management
O. S. Mydhili *
Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, India.
M. Surendran *
M. S. Swaminathan Rice Research Station, Moncompu, Alappuzha, India.
N. V Radhakrishnan
Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, India.
Susha S. Thara
Department of Plant Pathology, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, India.
K. P. Sindura
Department of Molecular Biology and Biotechnology, College of Agriculture, Vellayani, Thiruvananthapuram, Kerala, India.
*Author to whom correspondence should be addressed.
Abstract
Rice stem rot caused by Nakataea oryzae (syn. Magnaporthe salvinii; anamorph Sclerotium oryzae) is an important disease that can adversely affect rice production, particularly under intensive cultivation conditions. This review summarises the current knowledge on the taxonomy, morphology, disease cycle, and cultural, morphological, pathogenic, and molecular variability of the pathogen. The review also examines rice–pathogen interactions, host defence mechanisms, artificial inoculation and disease assessment methods, host resistance, and different disease management strategies. Considerable variability among N. oryzae isolates has been reported, which complicates pathogen characterisation, resistance screening, and the development of durable resistance. Although several resistant rice genotypes, biological control agents, cultural practices, and effective fungicides have been identified, their performance can vary with pathogen diversity and environmental conditions. Therefore, integrated disease management combining host resistance, cultural practices, biological control, and judicious fungicide use offers a more sustainable approach to stem rot management. Further research is needed to clarify the relationship between molecular and pathogenic variability, standardise resistance screening and inoculation methods, identify stable resistance, and better understand the molecular basis of rice–N. oryzae interactions. Addressing these gaps will support the development of effective and sustainable strategies for managing rice stem rot.
Keywords: Rice stem rot, Nakataea oryzae, pathogen variability, host resistance, host–pathogen interaction, disease assessment, biological control, integrated disease management