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

Xiaoxia Zhang,Bangting Wu,Altus Viljoen,Wei Wang,Siwen Liu,Yanling Xie,Diane Mostert,Gang Fu,Chunyu Li,Dandan Xiang,Huoqing Huang,Jianghui Xie,Shuxia Lyu

doi:10.3390/pathogens10060670

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.

Highlights

IntroductionBanana (Musa spp.) is one of the most important fruits and a staple diet for millions of people in the world [1])
Attacks some AAB or ABB bananas; race 2 is pathogenic to cooking bananas such as ‘Bluggoe’ ABB; race 3 is no longer considered as Foc race since it only affects
We found that FocM35_1 expression induced cell death in N. benthamiana leaves as well as the INF1 control, but not the empty vector control (Figure 5b)

Summary

Introduction

Banana (Musa spp.) is one of the most important fruits and a staple diet for millions of people in the world [1]). Fusarium wilt on bananas, resulting in substantial yield losses. Four races of Foc have been classified based on different host banana types: race, which is responsible for the Gros. Attacks some AAB or ABB bananas; race 2 is pathogenic to cooking bananas such as ‘Bluggoe’ ABB; race 3 is no longer considered as Foc race since it only affects. Heliconia species [2]; Foc race 4 is pathogenic to race 1- and race 2-susceptible cultivars as well as the Cavendish cultivars (AAA), which are grown and consumed worldwide nowadays. Foc race 4 isolates are further divided into two groups: subtropical race 4 (STR4)

Methods

Results

Conclusion