Transmission and management of Burkholderia glumae causing panicle blight disease of rice

Abstract

Bacterial panicle blight (Burkholderia glumae) is one of the important diseases of rice newlinecausing 75% yield loss. Current global climate change may cause an increase in bacterial panicle newlineblight as prolonged hot and humid conditions prevailing during the rice-growing season. This newlinedisease may occur more frequently in tropical and semi-tropical countries and during growing newlineseasons with higher temperatures than normal. A survey was carried out in ten agro-climatic zones newlineof Odisha and disease samples were collected showing symptoms of panicle blight. In panicle newlineblight disease, affected panicles may have some or all of their florets blighted, the basal one third newlineportions of the florets will begin as a white or light grey colour separated by a reddish-brown newlinemargin from the rest of the floret, which eventually becomes straw coloured with green rachis. newlineUpright brown coloured panicles are typically observed in severely infected fields due to failure in newlinegrain filling. The highest panicle disease incidence (26.5%) was observed in Chamakhandi block newlineof Ganjam district followed by Deogard, Mayurbhanj districts. The lowest panicle disease newlineincidence (6.5%) was observed in Malkangiri block under South Eastern Ghat agro-climatic zone. newlineThe panicle disease incidence ranged from 7.0% to 24% in other districts. Three pathogens were newlineisolated from the infected seeds viz. Isolate 1, Isolate 5 and Isolate 7 were identified as newlineBurkholderia spp. by VITEK-2 showing positive result for D-Cellobiose, D- Glucose, D-Maltose, newlineD-Mannose, Mannitol, D-Sorbitol, Citrate (sodium), Malonate, L- Lactate alkalization, Succinate newlinealkalinisation, Courmarate and 0/129 resistance (comp. Vibrio) tests. The Sanger sequencing of newline16S rDNA confirmed the identity of Isolate 1 and Isolate 5 to be Burkholderia glumae whereas newlineIsolate 7 was confirmed to be Burkholderia gladioli. The morphological studies under Scanning newlineElectron Microscope revealed that Burkholderia glumae is as Gram negative, rod shaped newlinelophotrichous bacteria with 0.5-0.7 x 1.5-2.5 and#956;m in width and length