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Date: April 2019
Source: Plant Disease [edited]
[Ref: Azizi MMF, Rahman MAB, Ismail SI, et al. First report of _Pantoea ananatis_ causing leaf blight disease of rice in Peninsular Malaysia. Plant Disease 103, 'first look'.
Pantoea spp. cause severe diseases [on rice]. In September 2017 and April 2018, bacterial leaf blight of rice (MR269 and CL varieties) was observed in the states of Selangor and Kedah, with 80% disease incidence. Symptoms were water-soaked stripes with yellowing color, which later turned into brown stripes on the upper part of leaves.
From symptomatic leaves, 10 representative bacterial colonies were isolated. [For] all isolates, PCR amplification [for] Pantoea species was performed, each producing approximately 600 bp amplicon.
The sequences revealed 100% nucleotide identity to [a] P. ananatis reference strain. [A] phylogenetic tree constructed from all isolates indicated 99% similarity to P. ananatis reference strains. P. ananatis specific [PCR analysis] produced approximately 900 [bp] amplicon each, 96% identical to a P. ananatis reference strain.
To test pathogenicity, [a] bacterial suspension of each isolate was inoculated to rice seedlings of MR269 and CL varieties. All isolates produced symptoms within 2 weeks post. Symptoms appeared similar to those of natural infections. Control rice seedlings remained asymptomatic. Bacteria were re-isolated from symptomatic leaves and further identified as P. ananatis by sequencing, fulfilling Koch's postulate.
To the best of our knowledge, this is the 1st report of P. ananatis causing leaf blight disease of rice in Malaysia. With molecular-based approaches, a better understanding on the taxonomy of P. ananatis will help to improve and develop effective disease control strategies against this widely spreading pathogen of rice in Malaysia.
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[_Pantoea ananatis_ symptoms in rice may include lesions on stems, stem necrosis, and leaf blight. The pathogen has also been reported to cause sheath and grain rot, as well as kernel discolouration. _P. stewartii_, previously known to occur on rice seeds, has also recently been associated with a leaf blight of the crop (ProMED-mail post http://promedmail.org/post/20170504.5012251
). Both species are considered emerging rice pathogens.
The effects of different bacterial strains on hosts can vary dramatically. The bacteria are generally transmitted by insect vectors, plant material, and infected seed, making them a quarantine risk.
Species in the genus can cause diseases on a number of crops, such as Stewart's bacterial wilt on maize (_P. stewartii_); leaf blights of cereals, including rice (_P. agglomerans_); pink disease of pineapple (_P. citrea_); brown stalk rot of maize (_P. ananatis_ and a novel _Pantoea_ species); center rot of onion (_P. ananatis_); a bacterial blight of _Eucalyptus_ and a leaf blotch disease of sudangrass have also been associated with _Pantoea_ species.
Fruit bronzing of jack fruit, an emerging disease in southern Asia caused by _Pantoea stewartii_ subsp. _stewartii_, has been reported in Malaysia earlier (ProMED-mail post http://promedmail.org/post/20170905.5294905