Bolton, M.D.

Boshoven, J.C.

Thomma, B.P.H.J.

Wageningen Yield 

135GEWASBESCHERMING | JAARGANG 44 | NUMMER 5 | NOVEMBER 2013
[ THE PROCESS TO PROGRESS
Jordi C. Boshoven1, 
Melvin D. Bolton2 & 
Bart P.H.J. Thomma1
1 Laboratory of 
Phytopathology, 
Wageningen University, 
Droevendaalsesteeg 1, 
6708 PB Wageningen,  
The Netherlands
2 Agricultural Research 
Service, Northern Crop 
Science Laboratory, US 
Department of Agriculture, 
Fargo, ND 58102
Some homologs of Verticillium dahliae 
effector Ave1 contribute to virulence in 
other plant pathogens
Verticillium dahliae is a fungal pathogen that 
causes vascular wilt in a broad range of host 
plants, including commercially important crops. 
The immune receptor Ve1, of which homologs are 
found in several host plants, confers resistance 
to Verticillium race 1 strains in tomato. Genome 
and RNA sequencing of V. dahliae race 1 and race 
2 strains resulted in the identification the highly 
expressed race 1-specific Ave1 gene that encodes 
the effector protein that is recognized by Ve1. 
Deletion of V. dahliae Ave1 does not only result in 
loss of recognition on Ve1 plants, but also makes 
the fungus less aggressive on tomato plants lack-
ing Ve1. Homologs of Ave1 were mainly found in 
plants, but also in the plant pathogens Fusarium 
oxysporum, Cercospora beticola, Colletotrichum 
higginsianum and Xanthomonas axonopodis. 
To determine whether these Ave1 homologs can 
contribute to virulence, V. dahliae Ave1 deletion 
mutants were complemented with the homo-
logs of F. oxysporum, C. beticola, C. higginsianum 
and X. axonopodis, and tested for aggressiveness 
on tomato plants lacking Ve1. Remarkably, only 
homologs of C. higginsianum and X. axonopodis 
complemented virulence of V. dahliae Ave1 dele-
tion mutants. This suggests that there are different 
functions among the various Ave1 homologs. Ave1 
deletion mutants are generated in F. oxysporum, C. 
beticola and C. higginsianum to study their contri-
bution to virulence in these pathogens.
SESSION 1b. Fundamental research
Language: English. Tarthorst Hall
An in vitro infection system for studying 
Phytophthora-host interactions using 
tomato cell suspensions
One of the most devastating plant diseases world-
wide is late blight on potato and tomato caused by 
the oomycete pathogen Phytophthora infestans. 
During the early biotrophic phase of infection, 
Phytophthora penetrates host tissue and thereafter 
forms specialized feeding structures called haus-
toria. Here, effectors produced by the pathogen, 
are transferred into the host cells to manipulate 
the host cell machinery thereby suppressing plant 
defense. Therefore, studying the interface between 
the host and the pathogen at the early stages 
of infection is of great interest. An important 
drawback when studying the Phytophthora-host 
interaction in leaves is the lack of synchronization 
of the infection process. For this purpose, a new 
in vitro infection system was established, in which 
MsK8 tomato cell suspensions were challenged 
with zoospores of different Phytophthora species. 
Here we show that P. infestans infects MsK8 cells in 
a similar fashion as leaf tissue. In contrast, other 
Phytophthora species that are not pathogenic on 
tomato could not penetrate the MsK8 cells. The 
use of this novel infection system allows simplifi-
cation and synchronization of the infection pro-
cess, and is expected to provide a more detailed 
insight into Phytophthora-host interaction.
Charikleia Schoina, 
Klaas Bouwmeester & 
Francine Govers
Laboratory of 
Phytopathology, 
Wageningen University, 
Droevendaalsesteeg 1, 
6708 PB Wageningen, 
The Netherlands
Dominant resistance against the 
Tomato spotted wilt virus in Capsicum 
annuum is triggered by the RNA 
silencing suppressor protein 
Resistance against Tomato spotted wilt virus 
(TSWV) isolates in Capsicum annuum is based on 
the dominant resistance gene Tsw. Unfortunately, 
resistance breaking isolates are meanwhile emerg-
ing and require monitoring and detection of their 
presence. Previous research performed on the 
identification of the avirulence determinant, the 
viral component triggering the resistance, showed 
contradictory results and left the issue unsettled. 
The first aim in my project was to determine 
which TSWV viral protein triggered the 
hypersensitive response (HR). For this a suitable 
transient expression system in Capsicum 
annuum had to be established, and this allowed 
us to identify the NSs protein of TSWV as the 
avirulence determinant of Tsw-mediated 
resistance in Capsicum annuum. In a next study 
we investigated whether the ability of NSs to 
trigger the Tsw-mediated resistance was 
functionally linked to the other known function 
of the NSs protein; suppressing the antiviral 
RNAi response. We were able to show that one 
function could be disrupted while the other 
Dryas de Ronde
Laboratory of Virology, 
Wageningen University, 
Droevendaalsesteeg 1, 
6708 PB Wageningen


Some homologs of Verticillium dahliae effector Ave1 contribute to virulence in other plant pathogens

Abstract

Similar works

Full text

Available Versions

Wageningen Yield

NARCIS

Name not available