A bacterium of the genus Pantoea ananatis, which may pose a threat to rice cultivation, has been discovered in the Kuttanad agro-ecosystem for the first time.
According to researchers who made the discovery, the bacteria cause a disease that affects paddy ears with symptoms similar to bacterial leaf blight. The study carried out by T.S. Reshma, a researcher at the Department of Postgraduate Studies and Research in Botany, SD College, Alappuzha; C. Dileep, associate professor at the college; and Smitha Balan, assistant director, Kerala Centre for Pest Management; was published in the Canadian Journal of Plant Pathology.
Symptoms
According to the researchers, grain discolouration and leaf blight caused by Pantoea ananatis were first observed in rice plants grown under field conditions in Kuttanad in July 2021. "The early symptoms included grain discolouration, stem lesions and leaf blight. Later mature seeds failed to develop, leaving only chaff. The leaves showed yellowish to brown lesions that turned a pale white to a straw colour as the disease progressed," reads the study.
Prior to the discovery of Pantoea ananatis, the only bacterial disease of rice reported from Kuttanad is bacterial blight caused by Xanthomonas spp. Though the ability of the new bacteria to spread disease is relatively low at present, the researchers warned that it might pose a threat in the future.
Emerging threat
According to them, Pantoea ananatis is an emerging threat to rice production worldwide and a better understanding of its pathogenicity is required. "To our knowledge, this is the first report of this pathogen from Kerala. The exceptional geography of Kuttanad necessitates an intense consideration for crop management and economic sustainability. There are only limited data available from the published literature regarding Pantoea ananatis infection of cereals. The host-pathogen interactions and pathogen virulence genes have not yet been studied in detail. Effective disease management, including chemical and biological controls, need to be developed for the prevention of disease transmission and crop loss," the researchers said.
Grain discolouration and leaf blight caused by Pantoea ananatis have been reported in China, Russia and Korea. Prior to its discovery from Kuttanad, the only case of Pantoea ananatis in India, where it was found to be responsible for causing leaf blight in Basmati rice in north India, was reported in 2011.
