A leaf spot disease of brassicas caused by Xanthomonas campestris pv. raphani
J. G. Vicente, B. Everett
Warwick HRI, The University of Warwick, Wellesbourne, Warwick CV35 9EF, UK
and S. J. Roberts
Current address: Plant Health Solutions, 20 Beauchamp Road, Warwick CV34 5NU, UK
Leaf-spot disease of Brassicaceae crops and other hosts
● Attributed to either X. campestris pv. armoraciae (McCulloch) Dye or X. campestris pv. raphani (White) Dye
● Other pathovars of X. campestris including X. campestris pv. campestris, the cause of black rot, can produce leaf
●
●
spots, but the host range of this disease is narrower and the symptoms are distinct
X. campestris leaf-spot isolates are sometimes obtained from commercial brassica seed
The aim of this study was to clarify the nomenclature of X. campestris leaf spot isolates
Pathogenicity
Identification of races
● Inoculation methods:
1. spray inoculation of bacterial suspension followed by 24-48h high humidity
2. pin inoculation with entomological pin charged with bacterial growth
● Results recorded after one and two weeks
● Isolates received as either X. campestris pv. raphani and pv. armoraciae that
caused leaf spots and dark sunken lesions in the middle vein, petiole and/or stem
when spray and pin inoculated into a susceptible B. oleracea cultivar (Wirosa F1)
were selected
● Twenty-five leaf-spot isolates were inoculated into a range of hosts
Examples of reactions of plant accessions to Xanthomonas campestris pv. raphani
Reaction
Hosts
Cultivar/line
Very susceptible
to all races
Savoy cabbage (B. oleracea var. sabauda)
Ethiopian mustard (B. carinata)
Radish (Raphanus sativus)
Tomato (Lycopersicon esculentum)
Wirosa F1
Selection of PI 199947
French Breakfast 3
Moneymaker
Susceptible
Pumpkin (Cucurbita maxima)
Cucumber (Cucumis sativus)
Tobacco (Nicotiana tabacum)
F1 Becky
Telegraph Improved
White Burley
Weakly susceptible
Horseradish (Armoracia rusticana)
Resistant to race 1
(and susceptible to 2 and 3)
Oilseed rape (B. napus var. oleifera)
Mustard (B. juncea)
Turnip (B. rapa var. rapifera)
Wallflower (Cheiranthus cheiri)
Cobra line 14R
Florida Broad Leaf
Just Right Hybrid
Cloth of Gold
Resistant to race 2
(and susceptible to 1 and 3)
Cauliflower (B. oleracea var. botrytis)
Radish (R. sativus)
Pepper (Capsicum annuum)
Miracle F1
Mino Early
Worldbeater
Variable
Candytuft (Iberis sp.)
White Empress
Resistant to all races
Stock (Matthiola incanae)
Brompton mixed colours
Radish Mino Early
Spray inoculated
Pin inoculated
HRI 6496 (race 1)
HRI 6490 (race 1)
Tomato
HRI 8305 (race
(race 2)
Frequency of occurrence, host of origin and geographical distribution of
Xanthomonas campestris pv. raphani races amongst 25 isolates
Race Host of origin
type (number of isolates)
Geographical origin
(number of isolates)
Total number
of isolates
1
Brassica oleracea (5)
Raphanus sativus (2)
Unknown (3)
France (3)
Southern Hemisphere (2)
US (2)
Unknown (3)
10
2
Brassica rapa (3)
Unknown (1)
Japan (2)
USA (1)
Unknown (1)
4
3
Brassica oleracea (4)
Brassica rapa (2)
Raphanus sativus (1)
Lycopersicon esculentum (1)
Unknown (3)
France (2)
Japan (1)
Canada (1)
USA (4)
E. Asia (1)
Unknown (2)
11
Host (Resistance genes)
Wirosa
Cobra
Miracle
Race
(R1)
(R2)
(Avirulence
genes)
3
2
(A2)
1
(A1)
Leaves (adaxial
(adaxial side) of Savoy cabbage cv.
cv. Wirosa F1,
B. napus Cobra line 14R and cauliflower cv.
cv. Miracle F1
spray inoculated with X. campestris pv.
pv. raphani
isolates HRI 8297 (race 1), 6520 (race 2) and 8303 (race
3) together with a postulated genegene-forfor-gene model.
rep-PCR fingerprinting
● High variability between X. campestris pv. raphani isolates even within the same race
● But X. campestris pv. raphani isolates clustered separately from pv. campestris
100
95
90
85
80
75
70
65
Species Pathovar Race Isolate
5235
X. vesicatoria
8302
X. vesicatoria
Radish French Breakfast 3 spray
inoculated with HRI 8298 (race 1)
Pepper
Tobacco
Spray inoculated with HRI 6490 (race 1)
Comparison with other pathovars
● Causes a non-vascular disease
● Has a wide host range including most brassicas, ornamental crucifers, radish
and tomato
● Causes leaf spots and dark sunken lesions as described by White (1930)
● X. campestris pv. campestris, X. axonopodis pv. vesicatoria and X. vesicatoria
(syn. X. campestris pv. vesicatoria) have narrower host ranges
● X. campestris pv. armoraciae symptoms include leaf spots, but no sunken
lesions and is strongly pathogenic on horseradish and only weakly pathogenic on
some brassicas (McCulloch, 1929)
References:
McCulloch L. (1929) J. Agric. Res. 38: 269-287
8300
X. vesicatoria
White H.E. (1930) Phytopathology 20: 653-662
8301
X. axonopodis
pv. vesicatoria
X. campestris
pv. iberis
X. campestris
pv. campestris
6
6181
X. campestris
pv. campestris
6
6185
X. campestris
pv. campestris
1
3811
X. campestris
pv. campestris
1
3818A
X. campestris
pv. campestris
1
6195
X. campestris
pv. campestris
3
6412
X. campestris
pv. campestris
5
3880
X. campestris
pv. campestris
3
3851A
X. campestris
pv. campestris
3
5212
X. campestris
pv. campestris
5
6382
X. campestris
pv. campestris
5
3883
X. campestris
pv. campestris
2
3849A
X. campestris
pv. campestris
4
6189
X. campestris
pv. campestris
4
1279A
X. campestris
pv. campestris
4
6312A
X. campestris
pv. armoraciae
X. campestris
pv. raphani
2
6497
X. campestris
pv. raphani
2
6518
X. campestris
pv. raphani
2
8305
X. campestris
pv. raphani
3
8304
X. campestris
pv. raphani
3
8308
X. campestris
pv. raphani
2
6520
X. campestris
pv. raphani
3
6498
X. campestris
pv. raphani
3
6499
X. campestris
pv. raphani
3
8299
X. campestris
pv. raphani
3
8303
X. campestris
pv. raphani
1
6490
X. campestris
pv. raphani
1
6493
X. campestris
pv. raphani
1
6491
X. campestris
pv. raphani
1
7974
X. campestris
pv. raphani
1
7979
X. campestris
pv. raphani
3
6492
X. campestris
pv. raphani
3
6494
X. campestris
pv. raphani
1
8079
X. campestris
pv. raphani
1
8298
X. campestris
pv. raphani
1
6489
X. campestris
pv. raphani
1
6496
X. campestris
pv. raphani
1
8297
X. campestris
pv. raphani
3
8309
X. campestris
pv. raphani
3
6519
X. campestris
pv. raphani
3
8307
X. campestris
pv. incanae
6377
X. campestris
pv. incanae
6378
X. campestris
pv. cheiranthi
3777A
X. campestris
pv. cheiranthi
5219A
6375
6376
Dendrogram of genetic similarity of Xanthomonas campestris pv. raphani and other Xanthomonas isolates. Similarities were calculated from the
combined data of REP, ERIC and BOX primer sets using Dice’s coefficient. The dendrogram was obtained using the UPGMA method.
a The isolate HRI 6375 from candytuft (Iberis sp.) and the isolates HRI 3777A and HRI 5219A from wallflower (Cheiranthus cheiri) should be included in new
X. campestris pathovars.
Conclusions
The X.campestris leaf-spot isolates studied here were identified as pv. raphani and not pv. armoraciae
A new type-strain (HRI 6519) and race-type-strains (HRI 6490, 8305, 6519) were assigned for X. campestris pv. raphani
Acknowledgements
This work was funded by the UK Defra.
We thank the following researchers for supplying some of their isolates: Margreet Asma, Hacène Bouzar, Diane A. Cuppels, John P.
Damicone and Katsunori Tamura. We also thank Bio-Rad Laboratories Ltd for the use of FingerprintingTM II.