They represent the most important food crop in Uganda, Rwanda and Burundi and are significant as a cash crop and staple food throughout the Great Lakes region of East Africa. Uganda is the second largest producer of bananas/plantains (after India) according to statistics from the Food and Agriculture Organisation of the United Nations (http://faostat.fao.org cited by Biruma et al., 2007 and Vurro et al., 2010). Since 2001, the emergence of banana Xanthomonas wilt (BXW) disease has threatened the
livelihoods of tens of millions of East-African farmers (Tushemereirwe et al., 2004; Biruma et al., 2007). The disease has been known in Ethiopia on enset (Ensete ventricosum), a close relative of banana, since the 1960s (Shimelash et al., 2008). However, BXW has recently spread
to the Burundi, the Democratic Republic of Congo, Kenya, Rwanda, Tanzania and Uganda (Tushemereirwe et al., 2004; Ndungo et al., 2006; Biruma et al., 2007; Reeder et TGF-beta inhibitor al., 2007; Carter et al., 2010). The disease is characterized by premature ripening of fruits, internal brown discoloration of fruits and vascular tissues, wilting of bracts and male buds and progressive yellowing leading to complete wilting. Once established in an area, BXW spreads rapidly and often leads to complete loss of yield (Biruma et al., 2007). The etiologic agent of BXW is a Gram-negative bacterium, previously classified as Xanthomonas campestris pathovar musacearum (Xcm) (Young et al., 1978). A recent phylogenetic study (Aritua et al., 2008) suggested that rather than belonging to species X. campestris, the bacterium is more closely related to the selleck inhibitor species
Xanthomonas vasicola, which includes pathovars X. vasicola pathovar holcicola (Xvh) pathogenic to sorghum and X. vasicola pathovar vasculorum (Xvv) pathogenic to sugarcane (Saccharum officinarum) Farnesyltransferase and maize (Zea mays) (Ohobela & Claflin, 1987; Vauterin et al., 1992, 1995). Accordingly, Xcm can be considered as a new pathovar of species X. vasicola (Aritua et al., 2008). Aritua et al. (2008) also showed that strains of Xvh and Xvv were nonpathogenic on banana but were pathogenic on maize, whereas Xcm strains were pathogenic on both banana and maize. These pathogenicity data suggest a host-jump by a strain of Xvh or Xvv onto a Musa species, because the Xcm strains retained pathogenicity to maize (Aritua et al., 2008). Xanthomonas is a genus within the Gammaproteobacteria that includes >20 species and hundreds of pathovars of Gram-negative rod-shaped plant-pathogenic bacteria (Vauterin et al., 1995). This genus includes causative agents of several economically important diseases. Complete genome sequences have been determined for several members of the genus (da Silva et al., 2002; Lee et al., 2005; Qian et al., 2005; Thieme et al., 2005; Salzberg et al., 2008; Vorholter et al., 2008; Pieretti et al., 2009; Moreira et al., 2010). However, no complete genome sequence is available for X.