Outbreak of tomato wilt caused by Ralstonia solanacearum
in Tamil Nadu, India and elucidation of its genetic relationship
using multilocus sequence typing (MLST)
A. Balamurugan
&
A. Kumar
&
M. Muthamilan
&
K. Sakthivel
&
M. Vibhuti
&
M. Ashajyothi
&
N. Sheoran
&
A. Kamalakannan
&
A. Shanthi
&
T. Arumugam
Accepted: 25 December 2017 /Published online: 15 January 2018
#
Koninklijke Nederlandse Planteziektenkundige Vereniging 2018
Abstract High incidence of wilt disease (35–45%) of
tomato (Solanum lycopersicum L.) was recently ob-
served in two different locations of Tamil Nadu state
of India. Infected plants showed typical wilt symptoms
which include sudden green wilting of foliage followed
by drooping of leaves downwards. The characteristic
white milky ooze observed on the cut end of infected
stem indicated bacterial etiology. Upon isolation,
bacterium produced white fluidal irregular colonies with
characteristic pink center on 2, 3, 5 triphenyl tetrazolium
chloride amended nutrient medium. The bacterium
caused typical green wilting 4–5 days post inoculation
(dpi) on one month old tomato plants. The identity of
bacterium was confirmed as Ralstonia solanacearum
using 16S rRNA gene sequences as well as by
R. solanacearum specific PCR. Further studies con-
firmed that the bacterium belonged to race 1 and biovar
3. In depth genetic characterization using multilocus
sequence typing (MLST) revealed that the wilt out-
breaks in Tamil Nadu were caused by genetically dis-
tinct race 1 strains of R. solanacearum. While the iso-
late, TRsR found clustered with R. solanacearum iso-
lates previously reported from Andaman and Nicobar
Islands-India, TRsP is clustered with isolates reported
from Kerala, India. The results of our MLST based
genetic analysis clearly indicated horizontal spread of
bacterial wilt disease of tomato as a consequence of
pathogen migration with the expansion of cultivation
in India.
Keywords MLST
.
Ralstonia solanacearum
.
Tomato
bacterial wilt
.
Tamil Nadu
.
Phylotype I
Tomato is an important vegetable crop worldwide and
bacterial wilt disease caused by Ralstonia solanacearum
is one of the most devastating disease all over the world
(Singh et al. 2015). Ralstonia solanacearum is a widely
distributed bacterial pathogen in tropical, sub-tropical
and certain temperate countries which cause vascular
Eur J Plant Pathol (2018) 151:831–839
https://doi.org/10.1007/s10658-017-1414-3
Electronic supplementary material The online version of this
article (https://doi.org/10.1007/s10658-017-1414-3) contains
supplementary material, which is available to authorized users.
A. Balamurugan
:
M. Muthamilan
:
A. Kamalakannan
Department of Plant Pathology, Centre for Plant Protection
Studies, Tamil Nadu Agricultural University, Coimbatore, Tamil
Nadu 641003, India
A. Kumar (*)
:
M. Vibhuti
:
M. Ashajyothi
:
N. Sheoran
Division of Plant Pathology, ICAR-Indian Agricultural Research
Institute, New Delhi 110012, India
e-mail: kumar@iari.res.in
K. Sakthivel
Division of Field Crop Improvement and Protection,
ICAR-Central Island Agricultural Research Institute, Port Blair,
Andaman and Nicobar Islands 744101, India
A. Shanthi
Department of Nematology, Centre for Plant Protection Studies,
Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu
641003, India
T. Arumugam
Department of Vegetable Crops, Tamil Nadu Agricultural
University, Coimbatore, Tamil Nadu 641003, India
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