Differences in symptom development in subterranean clover infected with Kabatiella caulivora Race 1 and Race 2 are related to host resistance

2002 ◽  
Vol 53 (3) ◽  
pp. 305 ◽  
Author(s):  
K. L. Bayliss ◽  
J. Kuo ◽  
K. Sivasithamparam ◽  
M. J. Barbetti ◽  
E. S. Lagudah
Keyword(s):  
Subterranean Clover ◽  
Post Inoculation ◽  
Vascular Bundles ◽  
Incompatible Interaction ◽  
Mesophyll Cells ◽  
Starch Grains ◽  
Race 1 ◽  
Kabatiella Caulivora ◽  
Race 2 ◽  
Clover Scorch

Clover scorch (Kabatiella caulivora) is a severe fungal disease of Trifolium spp. contributing to the collapse of pasture swards across southern Australia during warm, humid spring weather. Host plant responses associated with resistance to the disease were determined in 2 cultivars of subterranean clover (T. subterraneum) separately inoculated with K. caulivora Race 1 or Race 2. Germination of conidia of both races reached a maximum 5 days post-inoculation on cv. Woogenellup (susceptible to both races) and 4 days post-inoculation on cv. Daliak (resistant to Race 1 but susceptible to Race 2). Germ tube growth of Race 1 was inhibited on cv. Daliak and the percentage of conidia penetrating leaf surfaces was lowest on this race–cultivar combination. Susceptibility was characterised by large petiole lesions, with invasive hyphae extending through the mesophyll tissue into the pith and then through the phloem tissue of vascular bundles, eventually causing the petioles to collapse. Resistance was characterised by small, black lesions with invasive hyphae extending no further than the fourth layer of mesophyll cells. A suberin-based material was observed beneath infected mesophyll cells in the incompatible interaction, beyond which no further growth of hyphae occurred. Race 2 caused a faster rate of host tissue necrosis than Race 1 and also the breakdown of starch grains in uninvaded petiole tissues. Starch grains in plants infected with Race 1 were evenly distributed in uninvaded tissue. Sporulation was rarely observed in the incompatible interaction but was common in compatible interactions within 15 days post-inoculation. These responses to K. caulivora can now be used as a breeding tool in evaluating and selecting improved resistance to clover scorch disease among breeding lines of subterranean clover.

Resistance to race 1 of Kabatiella caulivora in subterranean clover (Trifolium subterraneum L.) cultivars and breeding lines

2008 ◽  
Vol 59 (6) ◽  
pp. 561 ◽  
Author(s):  
P. G. H. Nichols ◽  
M. P. You ◽  
M. J. Barbetti
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Breeding Lines ◽  
Race 1 ◽  
Kabatiella Caulivora ◽  
Selection For ◽  
Race 2 ◽  
Resistant Progeny ◽  
Clover Scorch

Twenty-eight cultivars and 106 F6-derived breeding lines of subterranean clover (Trifolium subterraneum) were screened in the field for their response to clover scorch disease caused by race 1 of Kabatiella caulivora. Eleven of the cultivars, including Denmark and Goulburn, were classified as resistant. Breeding lines with Denmark parentage had 55% of progeny with resistance, while those of Goulburn had only 19% of resistant progeny, suggesting different modes of inheritance. Selection for resistance to race 2 of K. caulivora in the F4 generation markedly increased the probability of selecting F6-derived lines with resistance to race 1, suggesting linkage between genes for resistance to both races.

Variability within Kabatiella caulivora Race 1 and Race 2 revealed by cultural and molecular analyses

2003 ◽  
Vol 54 (1) ◽  
pp. 77 ◽  
Author(s):  
K. L. Bayliss ◽  
L. Spindler ◽  
E. S. Lagudah ◽  
K. Sivasithamparam ◽  
M. J. Barbetti
Keyword(s):  
Aflp Analysis ◽  
Similarity Coefficients ◽  
Breeding Lines ◽  
Disease Site ◽  
Race 1 ◽  
Kabatiella Caulivora ◽  
Race Comparison ◽  
New Races ◽  
Race 2 ◽  
Clover Scorch

Kabatiella caulivora is the causal agent of clover scorch, a fungal disease of clover (Trifolium) species. Variability within and between K. caulivora Race 1 and Race 2 was determined by cultural characteristics, isozymes, and amplified fragment length polymorphisms (AFLP). Cultural studies indicated isolates from both races were highly variable. No differences were identified within or between races by isozyme analysis. Similarity coefficients, determined from AFLP analysis, indicated that isolates from different races were often more similar than isolates from the same race. Comparison of single representative isolates from Race 1 and Race 2, collected at a Denmark (Western Australia) disease site, with isolates collected from another site of clover scorch outbreak at Esperance, 300 km east of Denmark, indicated most of the isolates causing the second outbreak were similar to Race�2, confirming previously conducted pathogenicity tests. It is hypothesised that Race 2 may have evolved from Race 1, and that the level of variability in the pathogen indicates the potential for development of further new races of K. caulivora. The requirement for improved selection strategies, including the screening of new cultivars and breeding lines with multiple isolates of the pathogen, is discussed in relation to these findings.

Resistance to clover scorch disease (Kabatiella caulivora) among accessions of purple clover (Trifolium purpureum) and its relationship to the eco-geography of collection sites

2010 ◽  
Vol 61 (1) ◽  
pp. 44 ◽  
Author(s):  
P. G. H. Nichols ◽  
R. Snowball ◽  
M. F. D'Antuono ◽  
M. J. Barbetti
Keyword(s):  
Mediterranean Basin ◽  
Subterranean Clover ◽  
Disease Reaction ◽  
Severity Scores ◽  
Kabatiella Caulivora ◽  
Field Plots ◽  
Disease Severity Scores ◽  
Clover Scorch ◽  
The Mediterranean Basin ◽  
Collection Sites

Visual ratings of disease reaction to a mixture of races 1 and 2 of clover scorch (Kabatiella caulivora) were conducted on inoculated field plots of 206 accessions of Trifolium purpureum (191 var. purpureum and 15 var. pamphyllicum) collected from the Mediterranean basin and surrounding regions. Disease severity scores of the resistant check, cv. Denmark subterranean clover (T. subterraneum), were clearly differentiated from the susceptible check, cv. Paratta purple clover. Nearly 33% of the accessions were resistant to both races. Resistant plants tended to flower later and originate from higher latitudes, where K. caulivora is more widespread. The results of this investigation led to development of ELECTRA™, the first cultivar of purple clover with resistance to both races of K. caulivora.

Breakdown in resistance of subterranean clovers to clover scorch disease (Kabatiella caulivora)

1995 ◽  
Vol 46 (3) ◽  
pp. 645 ◽  
Author(s):  
MJ Barbetti
Keyword(s):  
Western Australia ◽  
Subterranean Clover ◽  
Improvement Program ◽  
Kabatiella Caulivora ◽  
New Race ◽  
Field Plots ◽  
Clover Scorch ◽  
Disease Testing

In spring 1990, in the Australasian Subterranean Clover and Alternative Legume Improvement Program field plots at Denmark, Western Australia, subterranean clover cultivars and crossbred lines normally highly resistant to clover scorch disease caused by Kabatiella caulivora, were severely affected by this disease. Testing the response of subterranean clover varieties to Kabatiella isolates taken from plants from these plots indicates the arrival of a new race of the fungus. The new race differs from all other isolates in overcoming the previously outstanding resistance of cultivars Green Range, Junee, Daliak and Esperance.

Variation in pathogenicity and virulence of Phytophthora clandestina on four cultivars of subterranean clover

1995 ◽  
Vol 35 (6) ◽  
pp. 717 ◽  
Author(s):  
A Purwantara ◽  
SP Flett ◽  
PJ Keane
Keyword(s):  
Growth Rate ◽  
Agar Medium ◽  
Sandy Loam ◽  
Severe Disease ◽  
Subterranean Clover ◽  
Race 1 ◽  
Pathogenicity Tests ◽  
Loam Soil ◽  
Race 2 ◽  
Cultivar Specificity

The pathogenicity of 6 isolates of Phytophthora clandestina on seedlings of 4 cultivars of subterranean clover was studied. There was a highly significant isolate x cultivar interaction in pathogenicity tests on axenic seedlings and seedlings grown in pasteurised potting mix or untreated sandy loam soil, indicating the existence of race-cultivar specificity. The isolates showed differences in virulence against the cultivars. Three isolates (race 0) caused severe disease only on Woogenellup; 2 isolates (race 1) caused severe disease on Larisa, Trikkala, and Woogenellup, but not on Meteora; one isolate (race 2) caused severe disease on Meteora and Woogenellup, but not on Larisa and Trikkala. As well as differing in virulence (the ability of a race to attack a range of cultivars), the races also differed in their aggressiveness on Woogenellup, with race 2 being the most, and race 0 the least, pathogenic. The isolates varied in their growth rate on agar medium, but this was not related to virulence or aggressiveness.

scholarly journals Incidence of Fusarium oxysporum f. sp. lycopersici Races in Tomato in Sinaloa, Mexico

Plant Disease ◽  
2010 ◽  
Vol 94 (11) ◽  
pp. 1376-1376 ◽  
Author(s):  
P. Sánchez-Peña ◽  
S. O. Cauich-Pech ◽  
J. Núñez-Farfán ◽  
R. D. Núñez-Cebreros ◽  
S. Hernández-Verdugo ◽  
...  
Keyword(s):  
Fusarium Oxysporum ◽  
Fusarium Wilt ◽  
Vascular Bundles ◽  
Potato Dextrose Broth ◽  
Solanum Lycopersicum L ◽  
Differential Cultivars ◽  
Differential Cultivar ◽  
Race 1 ◽  
Production Area ◽  
Race 2

Sinaloa State is the main producer of tomatoes (Solanum lycopersicum L) in Mexico where production attained 15,784 ha in 2008 (3). Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici (Sacc) Snyder & Hansen causes significant yield losses in Sinaloa each year (2). Three pathotypes or races of F. oxysporum f. sp. lycopersici have been described: races 1, 2, and 3 (1). The purpose of this study was to determine the races of F. oxysporum f. sp. lycopersici present in Sinaloa and distribution of these races in the region. F. oxysporum f. sp. lycopersici isolates were obtained from plants showing symptoms of yellowing and necrosis of vascular bundles. Plants were sampled from 50 fields throughout the production area in Sinaloa from November 2008 to March 2009. Four differential cultivars were used to identify the races of 26 F. oxysporum f. sp. lycopersici isolates collected across Sinaloa: Bonny Best (susceptible to all races), UC-82-L (susceptible to races 2 and 3), F1 MH-1 (susceptible to race 3), and IR-3 (resistant to all races). A microconidial suspension was prepared for each isolate (1 × 106 CFU/ml) from cultures grown in potato dextrose broth with constant agitation (110 rpm) at 28°C for 7 days. Five 25-day-old seedlings (three fully expanded true leaves) from each differential cultivar were immersed in the appropriate microconidial suspension for 10 min, then individually transplanted into a pot containing 1 kg of sterilized commercial potting mix, and grown in a growth chamber at 25 to 28°C and 60 to 75% relative humidity for 5weeks with 14-h light/10-h darkness. Control plants (root dipped for 10 min in sterile water) were grown similarly and remained asymptomatic. Susceptible cv. Bonny Best showed typical symptoms of Fusarium wilt including epinasty, yellowing, defoliation, vascular necrosis, and wilt. None of these plants survived 25 days postinoculation for any of the isolates. All UC-82-L plants inoculated with each of the 26 isolates died before 35 days, indicating that none of the isolates was of race 1. F1 MH-1 plants only survived inoculation with 3 of the 26 isolates (11.5%), indicating that the 23 isolates that killed these plants (88.5% of the 26 isolates) were of race 3, and only 3 isolates were of race 2. All IR-3 plants inoculated with the 26 isolates survived. The isolates showed variation in response to the differential cultivar UC-82L in duration from inoculation to when the plants died (variation in isolate aggressiveness). The three F. oxysporum f. sp. lycopersici race 2 isolates were restricted to the Culiacan Valley, whereas the 23 F. oxysporum f. sp. lycopersici race 3 isolates were widely distributed across Sinaloa. Koch's postulates were confirmed by reisolating the fungus from the roots and stem base of each dead, inoculated plant (4). This study provides baseline data for future surveys to monitor changes in distribution of F. oxysporum f. sp. lycopersici races in Sinaloa, Mexico. References: (1) G. Cai et al. Phytopathology 93:1014, 2003. (2) P. Sánchez-Peña. Programa de Fomento y Apoyo a Proyectos de Investigación (PROFAPI), Universidad Autónoma de Sinaloa, México, 2007. (3) Secretaría de Agricultura, Ganadería, Desarrollo Rural, Pesca y Alimentación, Servicio de Información Agroalimentaria y Pesquera, México. www.siap.gob.mx , 2009. (4) B. A. Summerell et al. Plant Dis. 87:117, 2003.

Variation in, and inheritance of seedling and adult-plant resistance in subterranean clover (Trifolium subterraneum L.) to leaf scorch (Kabatiella caulivora) (Kirch.) Karak

1990 ◽  
Vol 41 (1) ◽  
pp. 115 ◽  
Author(s):  
M Chandrashekar ◽  
GM Halloran
Keyword(s):  
Dominant Gene ◽  
Recessive Gene ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Single Recessive Gene ◽  
Seedling Resistance ◽  
Kabatiella Caulivora ◽  
The Cross ◽  
Clover Scorch ◽  
Adult Plants

The disease reaction of seedlings (2 weeks old) from a field collection of subterranean clover (Trifolium subterraneum) to clover scorch (Kabatiella caulivora (Kirch.) Karak), revealed 89 immune plants out of a total of 1530. However, with adult plants (15-16 weeks old) only one plant remained immune. In the F2 population of the cross of the cultivars (Daliak X Woogenellup (D X W), seedling resistance was conditioned by a single dominant gene and in the cross (Enfield X Woogenellup) (EX W) by a single recessive gene. However, with adult plants, resistance in the (D X W) F2 was conditioned by a single recessive gene and that in the (EX W) F2 by two recessive genes. The effect of increasing age in reducing the proportion of plants resistant to clover scorch in both studies indicates that caution is needed in evaluating resistance to clover scorch in epidemiological, breeding and genetic studies.

Sources of variation in the resistance of subterranean clover to clover scorch (Kabatiella caulivora) in the field

1975 ◽  
Vol 15 (75) ◽  
pp. 541 ◽  
Author(s):  
DL Chatel ◽  
CM Francis
Keyword(s):  
Regression Analysis ◽  
Multiple Regression Analysis ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
North African ◽  
Test Conditions ◽  
South West ◽  
Sources Of Variation ◽  
Kabatiella Caulivora ◽  
Clover Scorch

The resistance of 307 varieties of subterranean clover (Trifolium subterraneum) to the clover scorch disease pathogen was assessed in three locations in south west Australia. Disease intensity as measured by visual ratings of sward damage was found to vary with variety and location. Resistance was independent of subspecies groupings but dependent on country of origin. Spanish and Portugese varieties were generally less susceptible than North African selections. Disease severity was also related to plant characters by correlation and multiple regression analysis. Late maturing varieties were most resistant under the test conditions and rapidly growing earlier varieties, with large pale leaves and thick petioles, were least resistant.

New Trifolium subterraneum genotypes identified with resistance to race 2 of Kabatiella caulivora and cross-resistance to fungal root rot pathogens

2005 ◽  
Vol 56 (10) ◽  
pp. 1111 ◽  
Author(s):  
M. P. You ◽  
M. J. Barbetti ◽  
P. G. H. Nichols
Keyword(s):  
Coastal Region ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Cross Resistance ◽  
Pythium Irregulare ◽  
Breeding Lines ◽  
Root Pathogens ◽  
Kabatiella Caulivora ◽  
Breeding Selection ◽  
Race 2

One hundred subterranean clover genotypes including 72 advanced breeding lines from Trifolium subterraneum ssp. subterraneum and Trifolium subterraneum ssp. yanninicum and 28 Trifolium subterraneum commercial cultivars were screened in the field for resistance to race 2 of Kabatiella caulivora, and the resistances found were related to known resistance to major root pathogens in the region. Race 2 of K. caulivora causes severe damage on subterranean clover in the south-eastern coastal region of Western Australia and 72 of the 100 genotypes tested were resistant to this race, with levels similar to those shown by the cultivar Denmark. The unique importance of this study was that, for 12 genotypes of subterranean clover, these resistances were related to those shown to major root pathogens, viz. one or more of Phytophthora clandestina, Pythium irregulare, and Fusarium avenaceum. Availability of genotypes with such resistances to multiple pathogens is expected to be particularly valuable for the breeding/selection of subterranean clover in relation to the development of new cultivars with effective resistance to a range of pathogens that commonly occur in southern Australian annual legume pastures.

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