PMID- 36867585
OWN - NLM
STAT- Publisher
LR - 20240216
IS - 0191-2917 (Print)
IS - 0191-2917 (Linking)
DP - 2023 Mar 3
TI - First identification of Xanthomonas nasturtii as the cause of black rot of
watercress in Hawaii.
LID - 10.1094/PDIS-05-22-1043-PDN [doi]
AB - Watercress (Nasturtium officinale) has been in continuous production in Hawaii
for over a century and is part of the local diet. Black rot of watercress was
first identified as caused by Xanthomonas nasturtii in Florida (Vicente et al.,
2017), but symptoms of this disease have also been regularly observed in Hawaii
production in all islands, mostly during the rainy season from December to April
in areas with poor air circulation (McHugh & Constantinides, 2004). Initially,
this disease was attributed to X. campestris due to similar symptoms to black rot
of brassicas. Samples of watercress with symptoms that could be attributed to a
bacterial disease including yellow spots and lesions on leaves and stunting and
deformation of plants in more advanced stages, were collected from a farm in Aiea
in the island of Oahu, Hawaii, in October 2017. Isolations were performed at the
University of Warwick. Fluid from macerated leaves was streaked into plates of
King's B (KB) medium and Yeast Dextrose Calcium Carbonate Agar (YDC). After 48-72
hrs incubation at 28 degrees C, the plates showed a range of mixed colonies. Single
cream-yellow mucoid colonies were sub-cultured several times and pure isolates
including WHRI 8984 were stored at -76 degrees C as previously described (Vicente et al.,
2017). Colony morphology was observed in KB plates and, in contrast to the type
strain from Florida (WHRI 8853 = NCPPB 4600), isolate WHRI 8984 did not cause
browning of the medium. Pathogenicity was tested on four-week old watercress and
Savoy cabbage cv. Wirosa F1 plants by inoculations on leaves as previously
described (Vicente et al., 2017). WHRI 8984 did not produce symptoms when
inoculated on cabbage but produced typical symptoms on watercress. A re-isolation
from a leaf showing a V-shaped lesion, produced isolates with the same
morphology, including isolate WHRI 10007A, that was also shown to be pathogenic
to watercress therefore completing the Koch's postulates. Fatty acid profiling
was performed on WHRI 8984 and 10007A and controls grown on trypticase soy broth
agar (TSBA) plates at 28 degrees C for 48 hrs as described by Weller et al. (2000).
Profiles were compared with the RTSBA6 v6.21 library; as the database does not
include X. nasturtii, the results were only interpreted at the genus level, and
both isolates were shown to be Xanthomonas sp. For molecular analysis, DNA was
extracted and the gyrB partial gene was amplified and sequenced as described by
Parkinson et al. (2007). Comparisons with sequences available in the National
Centre for Biotechnology Information (NCBI) databases using the Basic Local
Alignment Search Tool (BLAST) showed that partial gyrB of WHRI 8984 and 10007A
were identical to the type strain from Florida therefore confirming that they
belong to X. nasturtii. For whole genome sequencing, genomic libraries for WHRI
8984 were prepared using Illumina's Nextera XT v2 kit and sequenced on a HiSeq
Rapid Run flowcell. The sequences were processed as previously described (Vicente
et al., 2017) and the whole genome assembly has been deposited in GenBank
(accession QUZM00000000.1); the phylogenetic tree shows that WHRI 8984 is close,
but not identical to the type strain. This is the first identification of X.
nasturtii in watercress crops in Hawaii. Control of this disease generally
involves the use of copper bactericides and minimizing moisture on leaves by
reducing overhead irrigation and increasing air circulation (McHugh &
Constantinides, 2004); seed testing might help to select batches that are disease
free and, in longer term, breeding for disease resistance might produce cultivars
that can be part of management strategies.
FAU - Vicente, Joana G
AU - Vicente JG
AD - Fera Science Ltd, 16233, York, United Kingdom of Great Britain and Northern
Ireland.
AD - University of Warwick, 2707, School of Life Sciences, Coventry, United Kingdom of
Great Britain and Northern Ireland; joana.vicente@fera.co.uk.
FAU - McHugh, John
AU - McHugh J
AD - Plant Industry Division, Department of Agriculture, Honolulu, Hawaii, United
States; jjmchughjr@gmail.com.
FAU - Bryning, Adam
AU - Bryning A
AD - Fera Science Ltd, 16233, York, United Kingdom of Great Britain and Northern
Ireland; adam.bryning@fera.co.uk.
FAU - Carroll, Sarah
AU - Carroll S
AD - Fera Science Ltd, 16233, York, United Kingdom of Great Britain and Northern
Ireland; sarah.carroll@fera.co.uk.
FAU - Harrison, James
AU - Harrison J
AD - University of Exeter, 3286, College of Life and Environmental Sciences, Exeter,
United Kingdom of Great Britain and Northern Ireland; J.W.Harrison@exeter.ac.uk.
FAU - Studholme, David
AU - Studholme D
AD - University of Exeter, 3286, College of Life and Environmental Sciences, Exeter,
United Kingdom of Great Britain and Northern Ireland; d.j.studholme@exeter.ac.uk.
LA - eng
PT - Journal Article
DEP - 20230303
PL - United States
TA - Plant Dis
JT - Plant disease
JID - 9882809
SB - IM
OTO - NOTNLM
OT - Nasturtium officinale
OT - Xanthomonas nasturtii
OT - Fatty Acid Profiling
OT - black rot
OT - gyrB
OT - identification
OT - sequencing
OT - watercress
EDAT- 2023/03/04 06:00
MHDA- 2023/03/04 06:00
CRDT- 2023/03/03 13:13
PHST- 2023/03/03 13:13 [entrez]
PHST- 2023/03/04 06:00 [pubmed]
PHST- 2023/03/04 06:00 [medline]
AID - 10.1094/PDIS-05-22-1043-PDN [doi]
PST - aheadofprint
SO - Plant Dis. 2023 Mar 3. doi: 10.1094/PDIS-05-22-1043-PDN.