English

Abstract

Bacterial wilt disease has caused a serious threat to the banana industry in Malaysia. The disease is always associated with Moko disease caused by Ralstonia solanacearum. The bacterium forms irregular round, creamy colonies with red centres when cultured on Kelman’s tetrazolium chloride (TZC) medium. Moko disease has been interchangeably identified as blood disease as both of them cause similar wilting symptoms on banana. Therefore, the present study was carried out to detect the occurrence of bacterial wilt in Selangor through comprehensive procedures on morphology, molecular, pathogenicity and specificity tests. Isolation of bacteria was conducted on infected plant samples (fruit stalk, fruit pulps, stem and root) collected in the field by plating on TZC medium. Bacteria colonies that are Gram-negative, oxidase-positive, and obligate aerobe were chosen for further identification through polymerase chain reaction (PCR) using 759F and 760R primers. Molecular identification showed the bacteria that colonized the infected plants is confirmed as BDB, which is very closely related to R. solanacearum. After Koch’s Postulate and pathogenicity test on tomato, wilting symptoms were found on all banana plantlets after two weeks. The bacterium did not cause any wilting symptom on tomato plantlets. The present study revealed the distribution of blood disease in Selangor, after the first report in Perak. It also suggested that both morphology and DNA-based identification are necessary for the detection of the pathogen that causes bacterial wilt in banana. © 2016 Friends Science Publishers