Fusarium Yellows of Ginger (Zingiber officinale Roscoe) Caused by Fusarium oxysporum f. sp. zingiberi Is Associated with Cultivar-Specific Expression of Defense-Responsive Genes

Abstract

Ginger (Zingiber officinale Roscoe) is an important horticultural crop, valued for its culinary and medicinal properties. Fusarium yellows of ginger, caused by Fusarium oxysporum f. sp. zingiberi (Foz), is a devastating disease that has significantly reduced the quality and crop yield of ginger worldwide. The compatible interaction between ginger and Foz leading to susceptibility is dissected here. The pathogenicity of two Foz isolates on ginger was confirmed by their ability to colonise ginger and in turn induce both internal and external plant symptoms typical of Fusarium yellows. To shed light on Foz susceptibility at the molecular level, a set of defense-responsive genes was analysed for expression in the roots of ginger cultivars challenged with Foz. These include nucleotide-binding site (NBS) type of resistant (R) genes with a functional role in pathogen recognition, transcription factors associated with systemic acquired resistance, and enzymes involved in terpenoid biosynthesis and cell wall modifications. Among three R genes, the transcripts of ZoNBS1 and ZoNBS3 were rapidly induced by Foz at the onset of infection, and the expression magnitude was cultivar-dependent. These expression characteristics extend to the other genes. This study is the first step in understanding the mechanisms of compatible host–pathogen interactions in ginger.

Impact of inoculum density of Fusarium oxysporum f. sp. zingiberi on symptomatic appearances and yield of ginger (Zingiber officinale Roscoe)

“…on a rotating platform (Ratek, Victoria, Australia). The spores were then extracted, counted and adjusted using sterile water to 10 2 , 10 4 , 10 6 , 10 7 and 10 8 microconidia ml −1 for inoculation on ginger plants, as per a previous study [9]. DNA was extracted from the mycelia of the four isolates using a microwave method [16].…”

“…Interval symptom was scored using a 1–6 severity scale based on the visual identification of discoloured regions in the rhizome (). Reisolation of Foz in the rhizome, roots and tillers was performed according to a previous study [9].…”

“…TEF-1α sequences representing 156 isolates belonging to four Fusarium species complexes were retrieved from previous studies [9,15,17,18]. Geneious Prime v 2023.0.1 (Biomatter Pty Ltd, Auckland, New Zealand) was used for the phylogenetic reconstruction of the isolates.…”

“…TEF-1α sequences representing 156 isolates belonging to four Fusariumspecies complexes were retrieved from previous studies [9,15,17,18]. Geneious Prime v 2023.0.1 (Biomatter Pty.…”

“…Commercial production of ginger in Australia relies predominantly on two commercial ginger cultivars, Canton and Queensland [11]. However, both cultivars are susceptible to Foz [9,12]. The need to address the lack of Foz-and other pathogen-resistant genotypes in the Australian ginger industry [13] is an important priority for research and investment [14].…”