Evaluation of Fusarium wilt resistance among Thai banana cultivars (Musa spp.)

Fusarium wilt disease (FWD) is caused by the soil-borne fungus Fusarium oxysporum  f. sp.  cubense  ( Foc ) and results in severe devastation of global commercial banana production. Foc -resistant banana genotypes show promise for sustainable effective control of FWD. ScaU1001 and ScaS0901 markers and their putative banana cultivars were evaluated for FWD resistance under greenhouse conditions after artificial infection by Foc race 1 ( Foc 1). The Foc 1 genotype was characterized from six Fusarium fungi isolated from the pseudostem of banana cv. ‘Kluai Namwa’ (ABB genome) using specific primer ( Foc 1), resulting in two Foc isolates (PL3 and PL6) with an expected 354bp PCR product. Both ScaU1001 and ScaS0901 markers were amplified as a unique PCR product (1694bp and 1429bp, respectively) in two banana cultivars ‘ Kluai Khai Kasetsart 2’ (AA genome) and ‘ Kluai Hom Khiew ’ (AAA genome), indicating that both cultivars probably carried a Foc -resistant DNA fragment. These markers could not amplify an expected PCR product in twenty-one other banana cultivars, suggesting that the cultivars were Foc -susceptible banana genotypes. To evaluate FWD symptoms among six tested banana cultivars infected by Foc 1, only ‘ Kluai Khai Kasetsart 2’ and ‘ Kluai Hom Khiew ’ were considered as resistant to Foc 1. They exhibited a few yellowed lower leaves with a darkish-brown discoloration inside the pseudostem at 21 days post-inoculation. Results suggest that these markers show great promise to identify new Foc -resistant genotypes in banana germplasm and this will be beneficial for further genetic study to improve banana resistance to FWD in breeding programs.