The M35 Metalloprotease Effector FocM35_1 Is Required for Full Virulence of Fusarium oxysporum f. sp. cubense Tropical Race 4

Abstract

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) causes Fusarium wilt of banana, the most devastating disease on a banana plant. The genome of Foc TR4 encodes many candidate effector proteins. However, little is known about the functions of these effector proteins on their contributions to disease development and Foc TR4 virulence. Here, we discovered a secreted metalloprotease, FocM35_1, which is an essential virulence effector of Foc TR4. FocM35_1 was highly upregulated during the early stages of Foc TR4 infection progress in bananas. The FocM35_1 knockout mutant compromised the virulence of Foc TR4. FocM35_1 could interact with the banana chitinase MaChiA, and it decreased banana chitinase activity. FocM35_1 induced cell death in Nicotiana benthamiana while suppressing the INF1-induced hypersensitive response (HR), and its predicted enzymatic site was required for lesion formation and the suppression to INF1-induced HR on N. benthamiana leaves. Importantly, treatment of banana leaves with recombinant FocM35_1 accelerates Foc TR4 infection. Collectively, our study provides evidence that metalloprotease effector FocM35 seems to contribute to pathogen virulence by inhibiting the host immunity.

Genomic Characterization of Parengyodontium torokii sp. nov., a Biofilm-Forming Fungus Isolated from Mars 2020 Assembly Facility

“…are characterized by displaying a catalytic metal in the active site of the protein and a conserved consensus HEXXH motif. Lastly, the function of metalloprotease, belonging to the family M35, has been widely investigated in fungal genomes, and has been associated with facilitating the penetration of Sordariomycetes species in insect cuticles [76] or in plant hosts [77]. We also compared the profile of fungal-specific transcriptional factors among the Cordycipitaceae species (Figure 6).…”

“…Proteases are capable of breaking down protein substrates using a universal mechanism of activation of water by Zn 2+ ions and display multiple physiological functions [93]. Different families of metallopeptidases produced by pathogenic fungi are related to critical biological processes as well pathogenesis to human, plants, and insects [77]. More specifically, enzymes of the M24B family cleavage the N-terminal amino acid from peptides harboring a proline residue at the second position and are essential for cellular metabolic processes [94].…”

The secreted ribonuclease T2 protein FoRnt2 contributes to Fusarium oxysporum virulence

“…Similarly, the secreted cerato‐platanin protein FoCP1 is also required for the virulence of F. oxysporum on host plants (Liu et al, 2019 ). The M35 metalloprotease effector, another secreted protein, is also essential for full virulence (Zhang et al, 2021 ). In addition, FoEG1 can modulate host immunity and is required for the virulence of F. oxysporum (Zhang et al, 2021 ).…”

FoCupin1, a Cupin_1 domain-containing protein, is necessary for the virulence of Fusarium oxysporum f. sp. cubense tropical race 4

“…Foc4 has been further divided into tropical race 4 (Foc TR4) and subtropical race 4 (Foc STR4), which affect the Cavendish bananas in the tropics and subtropics, respectively ( Ploetz, 2015 ). Among Foc races, Foc TR4 has the strongest pathogenicity, and spread from the Asia-Pacific region to the Middle East, Africa, Australia, and Latin America ( Thangavelu et al, 2021 ; Zhang et al, 2021 ). Despite the serious damage caused by Foc TR4, efficient strategies for its management are not available to date and the understanding of its pathogenesis is still rudimentary ( Liu et al, 2019 ).…”

“…In Foc-banana interactions, effectors have been proven to act as pathogenicity factors and play important roles during the early infection stages ( Czislowski et al, 2018 ). Previous studies have reported several effectors in Fusarium oxysporum , including secreted in xylem (SIX; Czislowski et al, 2018 ), Necrosis proteins (NPP1; Oome et al, 2014 ), Cerato-Platanin ( Liu et al, 2019 ), hydrophobins ( Casarrubia et al, 2018 ), and M35 family metalloproteinases ( Zhang et al, 2021 ), which are all required by Foc4 for its penetration and full virulence.…”