A rapid technique for screening banana cultivars for resistance to Xanthomonas wilt

Abstract

The banana Xanthomonas wilt disease (BXW) has threatened the livelihood of millions of farmers in East Africa. Use of resistant varieties is the most cost-effective method of managing this bacterial disease. A reliable and rapid screening method is needed to select resistant banana varieties. An in vitro screening method was developed for early evaluation of Xanthomonas wilt resistance using small tissue culture-grown plantlets. Eight cultivars of banana were screened with sixteen isolates of Xanthomonas campestris pv. musacearum using this method. There were significant differences (P<0.0001) in susceptibility among the various banana cultivars tested, whereas no significant difference (P=0.92) in pathogenicity was observed between the pathogen isolates. The cv. Pisang Awak (Kayinja) was found to be highly susceptible and Musa balbisiana resistant. Nakitembe was found to be moderately resistant while cvs Mpologoma, Mbwazirume, Sukali Ndiizi, FHIA-17 and FHIA-25 were susceptible. The susceptibility of these cultivars was further tested in vivo by artificial inoculation of potted plants with similar results. This study shows that an in vitro screening test can serve as a convenient, cheap and rapid screening technique to discriminate BXW-resistant from BXW-susceptible banana cultivars.

Rapid screening of Musa species for resistance to Fusarium wilt in an in vitro bioassay

“…Considering banana germplasm is often exchanged or released as in vitro conserved plantlets, the bioassay would also have application in assessment of newly introduced accessions. Similar early evaluation methods have been developed for rapid screening of Musa species for resistance to black leaf streak (Twizeyimana et al 2007) and Xanthomonas wilt (Tripathi et al 2008), respectively. …”

Emerging infectious diseases of crop plants in developing countries: impact on agriculture and socio-economic consequences

“…It was reported in Uganda in 2001 on banana and from there it has spread rapidly to all regions of Africa where the crop is grown. No varieties have complete genetic resistance but they differ in degree of susceptibility (Tripathi et al 2008). The cultivar Pisang Awak, originating in Malaysia, is the most susceptible .…”

“…This, however, depends on the type of infection, the environmental conditions, the state of the plant and the cultivar. Infection can occur: in inflorescences, when the bacterium is carried by insect vectors (stingless bees, fruit flies) (Tinzaara et al 2006); by mechanical transmission due to the use of infected tools; in the roots when the soil is contaminated by infected plant debris Tripathi et al 2008); and by raindrops containing the bacterium. It can also be disseminated by planting infected propagating material.…”

“…Germplasm of some local varieties has resistance characteristics (Tripathi et al 2008) but these have no value as food so inclusion in breeding programs may not yield commercially viable germplasm. Also the genetic diversity of banana in Africa is very narrow.…”

Evaluation of banana genotype resistant to Xanthomonas wilts disease (Xanthomonas campestris pv. musacearum) in south east of Ethiopia

“…According to Tripathi et al (2008) and Getachew et al (2006), even though no natural banana cultivars and genome groups have complete genetic resistance to Xw, they differ in degree of susceptibility. However, research on Xanthomonas wilt that involves searching for resistant banana cultivars which generated under tissue culture protocol has been given very little due attention.…”