Association of Pantoea stewartii subsp. stewartii with ChrysSA genus flea beetles in jackfruit crops

Pantoea stewartii subsp. stewartii is the causal agent of the emerging disease in jackfruit crops (Artocarpus heterophyllus L.), known as "Fruit Bronzing". This disease affects the quality of fresh jackfruits, resulting in economic production losses. Thus far, the biology of the P. stewartii subsp. stewartii bacterium during the stages that make up the fruit bronzing disease ' s cycle is poorly understood. Therefore, to gain further insight into this emerging disease, we evaluated the association between P. stewartii subsp. stewartii and the jackfruit flea beetle, which could be involved in the dissemination of this bacterium in this crop. Five bacterial isolates were obtained from two of the six groups of field-collected flea beetles (Group I and Group VI). Morphological characteristics and PCR amplification employing taxon-specific primers both indicated the isolates were P. stewartii subsp. stewartii. AG085-I, AG086-I, AG087-I, and AG088-I were isolated from Group I flea beetles, and AG024-VI was isolated from Group VI flea beetles. Molecular analysis results showed that Group I flea beetles correspond to Chaetocnema minuta, while that Group VI flea beetles correspond to the ChrysSA genus. Finally, the molecular identification of bacterial isolates by analysis of the 16S rDNA and cpsD regions showed that the AG085-I, AG086-I, AG087-I, AG088-I isolates correspond to P. ananatis and only the AG024-VI isolate obtained from the Group VI flea beetles ChrysSA corresponds to P. stewartii subsp. stewartii. The AG024-VI isolate showed pathogenic potential against jackfruit. These results demonstrate the presence of CrhysSA sp. flea beetles associated with P. stewartii subsp. stewartii in jackfruit crops.