Development of Field Diagnostic Tools for and Characterisation of Xanthomonas campestris pathovar musacearum, Causal Agent of Banana Xanthomonas Wilt

Abstract

Xanthomonas campestris pathovar musacearum (Xcm) is the causal agent of Xanthomonas Wilt (XW) of Bananas. It is currently the greatest threat to the existence and production of bananas in Uganda and other neighboring countries. XW on banana is able to cause about 80-100% field losses. There are currently no known chemicals, herbicides or resistant banana cultivars that can be used to control this disease. Despite awareness efforts among farmers, this disease continues to bring down the yield of bananas in growing areas. This is also due to the fact that symptoms caused by XW are similar to, and often indistinguishable from those caused by manageable common banana diseases such as Fusarium wilt. The key control strategy of XW is immediate destruction of infected plants. There is therefore need for early and accurate detection of Xcm: an onsite field detection tool. There are currently PCR (polymerase chain reaction) laboratory based assays and antibody based systems that are used for detection of this bacterium. This study developed another antibody-based system: an ELISA polyclonal antibody assay for Xcm formatted in to a lateral flow device (LFD). This study also introduces a new pathovar, Xanthomonas vasicola pv musacearum, to the species Xanthomonas vasicola and therefore carried out large scale comparative pathogenicity testing of the X.vasicola pathovars on maize, banana and sugarcane. This study further characterized a new collection of Xcm isolates from Western Uganda to determine their genotypes based on a subset of the 86 Single Nucleotide Polymorphisms that divided Xcm isolates into two major sub- lineages (I&II) as previously reported (Wasukira et al, 2012).