Morpho-molecular Characterization and Cross Infection Pattern in Brown Spot Pathogen Infecting Rice (Oryza sativa) and Echinochloa spp.(Barnyard grass)
Loading...
Date
2023
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
SKUAST Kashmir
Abstract
Rice (Oryza sativa L.) is the staple food for half of the world’s population. Rice is among the three most important grain crops in the world, and it has a major contribution to fulfil the food needs across the globe. It is cultivated almost in all parts of the world, including USA, Japan, China, India, Indonesia etc. Rice production is greatly influenced by various biotic and abiotic stresses. Among biotic stresses, diseases such as bacterial leaf blight, rice blast, sheath rot, sheath blight and brown spot are the major contributors that lead to yield reduction (Kindo and Tiwari, 2015). Brown spot is historically an important disease of rice. This disease is also found to be associated with a weed, Echinochloa spp. The current study was undertaken to characterize the pathogen isolates from rice and Echinocholoa spp. on morpho-molecular basis, and to study their cross infection pattern. Twenty four brown spot pathogen isolates (twelve from each rice and Echinochloa) were sampled from three rice growing districts (Baramulla, Kulgam and Pulwama) of Kashmir. Variability in colony characteristics and radial growth was observed among the pathogen isolates. Maximum radial growth was observed in isolate BO1 (77mm) and the minimum in isolate BO10 (29.66mm).Among Echinochloa isolates, maximum radial growth was observed in isolate H4 (65.83mm) and the minimum in isolate H2 (47.83mm). The isolates also showed difference in conidial characteristics. Maximum conidial dimensions were observed in isolate BO1 (88.14 x 16.32µm) and the minimum in isolate BO9 (23.19 x 8.73µm). Conidia were light brown to dark brown in colour, shape was straight /curved to slightly curved, and 1-12 septate. Similarly, among the pathogen isolates from Echinochloa, maximum conidial dimensions were observed in isolate H2 (100.25 x 14.09µm) and the minimum in isolate H8 (41.31 x 11.12µm).Conidia were light brown to dark brown in colour, straight /curved to slightly curved, 2-10 septate. Based on ITS sequencing, majority of the isolates were identified as Bipolaris oryzae. Isolate BO9 was identified as Curvularia spicifera, isolate H2 as Exserohilum monoceras, isolate H8 and H9 as Bipolaris victoriae. All the isolates that were selected for cross infection studies showed positive cross infection, however rice isolates were more pathogenic to rice than Echinochloa crus-galli and vice versa. Exserohilum monoceras (isolate H2) was found highly pathogenic on Echinochloa crus-galli, produced only few spots on rice which makes it a potential mycoherbicide for the Echinochloa species. However, more in depth studies are needed in this aspect.
Description
Keywords
Brown spot, Bipolaris oryzae, Bipolaris victoriae, Cross infection, Curvularia spicifera, Echinochloa, Exserohilum monoceras, mycoherbicide, Rice, Plant Pathology.