Characterisation and pathogenicity of bacteria causing bacterial heart rot from Bestari Jaya, Selangor, Malaysia

Pineapples are a common commodity that can contribute to Malaysia's economy. However, like any crop in the agriculture and food production industry, pineapple growth is often affected by pests and diseases. Currently, the pineapple sector in Malaysia is facing a devastating disease known as Bacterial Heart Rot (BHR), caused by Dickeya zeae (formerly Erwinia chrysanthemi), which has also been observed in Bestari Jaya, Selangor. This study aims to characterise the bacteria responsible for Bacterial Heart Rot and determine its pathological effects on Malaysia's pineapple varieties. In this study, diseased fruit samples exhibiting heart rot symptoms were collected from various fields in the area. The results showed that all bacterial isolates from the diseased samples were rod-shaped, Gram-negative, and had a red/pink colour. Furthermore, during the pathogenicity test, all bacterial strains induced lesions on potato samples, and disease symptoms were also observed on healthy fruit samples that had been inoculated with the bacterial suspension. The pathogenicity test confirmed that the isolated bacteria were capable of causing symptoms similar to heart rot disease, including lesions, a foul smell, and odour. To satisfy Koch's Postulates, the isolated bacteria causal to heart rot disease were subjected to re-isolation. The results of the pathological effect on Malaysia's pineapple varieties revealed that the Crystal Honey variety exhibited the lowest percentage of disease severity compared to the MD-2 and Morris varieties. This study provides insights into the characteristics of the isolated bacteria responsible for causing heart rot in pineapples from Bestari Jaya, Selangor, and highlights their pathogenicity on Malaysia's pineapple varieties.