Damme, M.M.A., van

Faino, L.

Thomma, B.P.H.J.

Damme, van, M.M.A.

NARCIS 

Plant defence against Verticillium wilt disease through RNA silencing

Name not available

Wageningen Yield 

136 GEWASBESCHERMING | JAARGANG 44 | NUMMER 5 | NOVEMBER 2013
THE PROCESS TO PROGRESS ] 
Maaike van Agtmaal1, 
Maria Hundscheid1, 
Angela Straathof2 & 
Wietse de Boer1,2
1  Department of Microbial 
Ecology, Netherlands 
Institute of Ecology, 
P.O. Box 50, 6700 AB, 
Wageningen,  
The Netherlands
2 Department of Soil 
Quality, Wageningen 
University, P.O. Box 47, 
6700 AA, Wageningen, 
The Netherlands
function could be maintained, indicating that 
these were not functionally linked. We also looked 
into the effect of temperature on the ability to 
induce the resistance response. In general, 
dominant resistance genes are temperature 
sensitive, i.e. they are not functional above a 
certain temperature (Tsw: 32 °C). Besides this, 
a small group of TSWV isolates exhibited a 
temperature-dependent behaviour during 
induction of resistance, i.e they were able to 
induce (< 28 °C) or break the resistance (≥ 28 °C), 
depending on temperature. However, the 
underlying mechanism for this is unknown. 
Furthermore, we designed a diagnostic tool based 
on PCR to enable detection of resistance breaking 
isolates in the field.
Remote beneficials in soil; potential role 
of bacterial volatiles in suppression of 
soil-borne fungal pathogens
General disease suppression (GDS) in 
agricultural soils is attributed to nutrient 
competition within the microbial community. 
So far, the withdrawal of nutrients by non-
pathogenic microbes from soil or even from 
pathogen survival structures 
(e.g. spores) has been considered as the main 
mechanism by which pathogens are restricted 
in their ability to infect roots. However, besides 
nutrient deprivation (substrate competition), 
also inhibitory compounds released by microbes 
(interference competition), are found to 
contribute. As a consequence, not only the 
total soil microbial metabolic activity but also 
microbial species that produce inhibitory 
compounds, are involved in GDS. The relative 
importance of interference competition in GDS, 
and thus the relative importance of microbial 
community composition, is not yet known.
Antimicrobial volatile organic compounds, emit-
ted by soil bacteria, might be important candi-
dates based on their ability to diffuse through the 
soil network. Antifungal volatile production has 
been shown for a broad range of bacterial phyla; 
30-60% of the soil bacteria can produce inhibitory 
volatiles (Wheatley 2002; Zou 2007). Our experi-
ments aim to test the effect of these volatiles on 
the growth of fungal plant pathogens and the 
ability to infect plant roots.
Results of these experiments show a strong re-
duction of mycelial density of fungal pathogens 
by volatiles emitted by soil bacteria in suppres-
sive soils whereas in soils conducive to disease 
no growth reduction was observed. Bioassays 
were performed to link the observed reduction in 
pathogen growth to crop infection. These correlat-
ed with volatile growth reduction thus showing 
a potential role of volatiles in both pathogen 
suppression and reduction of disease incidence. 
GC/MS analysis and 454 sequencing and were 
performed to identify the inhibitory volatiles and 
potential volatile producing bacterial taxa.
Plant defence against Verticillium wilt 
disease through RNA silencing 
RNA silencing is the regulation of gene expression 
based on the accumulation of sequence-specific 
small RNAs (sRNAs) that target messenger RNAs 
(mRNAs) resulting in their degradation. Several 
genes controlling RNA silencing in plants have 
been identified. The plant RNA silencing 
pathway has previously been shown to mediate 
plant immunity against viruses and bacteria. We 
are using the model plant Arabidopsis as a host of 
Verticillium to unravel the role of RNA silencing in 
Verticillium wilt disease.
Mireille van Damme, 
Luigi Faino &  
Bart Thomma
Laboratory of 
Phytopathology, 
Wageningen University, 
Droevendaalsesteeg 1, 
6708 PB Wageningen, 
The Netherlands


Plant defence against Verticillium wilt disease through RNA silencing

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