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.

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.

Novel Disease Host Resistances in the World Core Collection of Trifolium subterraneum

Plant Disease ◽  
2020 ◽  
Author(s):  
Ming Pei You ◽  
Phillip Nichols ◽  
Roseline Katusiime ◽  
Martin John BARBETTI
Keyword(s):  
Core Collection ◽  
Morphological Traits ◽  
Phenotypic Expression ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Damping Off ◽  
Pythium Irregulare ◽  
Breeding Programs ◽  
Foliar Diseases ◽  
Disease Parameters

Glasshouse and field investigations were undertaken into the phenotypic expressions of resistance of a 97-member World Core Collection of subterranean clover (Trifolium subterraneum), collected from its native Mediterranean habitat and representing around 80% of the total genetic diversity within the known 10,000 accessions of the species, against the most important damping-off and root rot (Phytophthora clandestina, and Pythium irregulare) and foliar (Kabatiella caulivora, Uromyces trifolii-repentis and Erysiphe trifoliorum)pathogens. An additional 28 diverse cultivars were also included. Associations were also examined for these genotypes between 18 disease parameters and 17 morphological traits and between these disease parameters and 24 climatic and eco-geographic variables from their collection sites. Many genotypes showed strong phenotypic expression of novel host disease resistance(s) against one or more pathogens, enabling their potential deployment as disease resistant parents into subterranean clover breeding programs. These new sources of resistance enable future ‘pyramiding’ of different resistance genes to improve resistance against these pathogens. Of particular value were genotypes with multiple disease resistances across soilborne and/or foliar diseases, as many of these pathogens co-occur. All diseases had some parameters significantly correlated with one or more morphological traits and with one or more site of origin variables. In particular, there were significant negative correlations between damping-off (i.e., germination) and eight of the 17 morphological characters. The outcome of these studies provides crucial information to subterranean clover breeding programs, enabling them to simultaneously select genotypes with multiple resistances to co-occurring soilborne and foliar diseases, in addition to desirable traits, to offer renewed hope for re-establishing a more productive subterranean clover livestock feedbase despite multiple diseases prevailing widely.

Genetic improvement of subterranean clover (Trifolium subterraneum L.). 2. Breeding for disease and pest resistance

2014 ◽  
Vol 65 (11) ◽  
pp. 1207 ◽  
Author(s):  
P. G. H. Nichols ◽  
R. A. C. Jones ◽  
T. J. Ridsdill-Smith ◽  
M. J. Barbetti
Keyword(s):  
Plant Breeding ◽  
Mosaic Virus ◽  
Pest Resistance ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Yellow Mosaic Virus ◽  
Genotypic Differences ◽  
Pythium Irregulare ◽  
Halotydeus Destructor ◽  
Subterranean Clover Stunt Virus

Subterranean clover (Trifolium subterraneum L.) is the most widely sown pasture legume in southern Australia and resistance to important diseases and pests has been a major plant-breeding objective. Kabatiella caulivora, the cause of clover scorch, is the most important foliar fungal pathogen, and several cultivars have been developed with resistance to both known races. Screening of advanced breeding lines has been conducted to prevent release of cultivars with high susceptibility to other important fungal foliar disease pathogens, including rust (Uromyces trifolii-repentis), powdery mildew (Oidium sp.), cercospora (Cercospora zebrina) and common leaf spot (Pseudopeziza trifolii). Several oomycete and fungal species cause root rots of subterranean clover, including Phytophthora clandestina, Pythium irregulare, Aphanomyces trifolii, Fusarium avenaceum and Rhizoctonia solani. Most breeding efforts have been devoted to resistance to P. clandestina, but the existence of different races has confounded selection. The most economically important virus diseases in subterranean clover pastures are Subterranean clover mottle virus and Bean yellow mosaic virus, while Subterranean clover stunt virus, Subterranean clover red leaf virus (local synonym for Soybean dwarf virus), Cucumber mosaic virus, Alfalfa mosaic virus, Clover yellow vein virus, Beet western yellows virus and Bean leaf roll virus also cause losses. Genotypic differences for resistance have been found to several of these fungal, oomycete and viral pathogens, highlighting the potential to develop cultivars with improved resistance. The most important pests of subterranean clover are redlegged earth mite (RLEM) (Halotydeus destructor), blue oat mite (Penthaleus major), blue-green aphid (Acyrthosiphon kondoi) and lucerne flea (Sminthurus viridis). New cultivars have been bred with increased RLEM cotyledon resistance, but limited selection has been conducted for resistance to other pests. Screening for disease and pest resistance has largely ceased, but recent molecular biology advances in subterranean clover provide a new platform for development of future cultivars with multiple resistances to important diseases and pests. However, this can only be realised if skills in pasture plant pathology, entomology, pre-breeding and plant breeding are maintained and adequately resourced. In particular, supporting phenotypic disease and pest resistance studies and understanding their significance is critical to enable molecular technology investments achieve practical outcomes and deliver subterranean clover cultivars with sufficient pathogen and pest resistance to ensure productive pastures across southern Australia.

scholarly journals Suitability of new subterranean clovers in the Canterbury region

2000 ◽  
pp. 161-165 ◽  
Author(s):  
K. Widdup ◽  
C. Pennell
Keyword(s):  
New Zealand ◽  
Seed Set ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Late Winter ◽  
Summer Drought ◽  
Seedling Regeneration ◽  
Breeding Lines ◽  
Herbage Yield ◽  
Late Maturity

The annual legume, subterranean clover, is adapted to permanent pastures in the summer drought-prone areas of eastern New Zealand. Dry summers over the last decade in Canterbury have renewed the interest from farmers in the use of sub clover. As the previously used cultivars Mt Barker and Tallarook are no longer available, a trial was established at AgResearch Templeton to evaluate a new series of cultivars and breeding lines from Australia together with recent New Zealand selections. The lines were sown in rows in May 1993 and assessed for seed set, autumn seedling regeneration and spring growth under sheep grazing for 4 years. The new Australian cultivars had improved seed set and consistently better seedling regeneration and herbage yield compared with older cultivars. The late-flowering, small-leaved and densely branched types were best adapted to the Canterbury environment. The late-maturity cultivars Denmark and Leura, selected from Sardinian germplasm, re-established 50% more seedlings and produced 25% greater late winter/ spring growth than Mt Barker and Tallarook in the third year. The New Zealand selection Ak 948 had similar performance to Denmark and Leura but the remaining selections were mediocre by the fourth year. The Sardinian ecotype breeding material appeared well-adapted to Canterbury conditions and future cultivars based on this material may be most suitable. Further trials are required in harsher sites to confirm these cultivar recommendations. Keywords: Australian cultivars, dry regions, herbage yield, seedling regeneration, subterranean clover, Trifolium subterraneum

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.

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.

Humidity, free water and light in relation to development of Kabatiella caulivora (Kirchn.) Karak in Trifolium subterraneum L. cv.Yarloo

1975 ◽  
Vol 26 (3) ◽  
pp. 511
Author(s):  
K Helms
Keyword(s):  
Light Intensity ◽  
Plant Growth ◽  
Free Water ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Disease Development ◽  
Kabatiella Caulivora ◽  
Spread Of Infection ◽  
Moisture Conditions ◽  
And Control

The effects of moisture conditions on disease development and plant growth were examined in subterranean clover plants which were inoculated with K. caulivora 4 weeks after sowing and were maintained after inoculation at 20°C and with a light intensity of 2000 f.c. In plants which received 100% relative humidity (RH) with free water on leaves, for at least 4 days after inoculation, 15–20% of leaves developed lesions within 11 days. In plants which received continuously 90% RH with free water on leaves, or 100% RH without free water on leaves, less than 1.5% of leaves developed lesions within 11 days. There was no evidence of spread of infection in plants maintained for 11 or 25 days after inoculation. The effects of light intensities of 2000, 500 and 125 f.c. on disease development and plant growth were examined in plants which received 100% RH with free water on leaves and were grown for 25 days after inoculation, either in simulated swards or in standard pots. In most treatments a reduction in light intensity from 2000 to 500 f.c. reduced the growth of plants but had no effect on the percentage of diseased leaves, whereas a reduction in light intensity from 500 to 125 f.c. reduced growth and increased the percentage of diseased leaves of plants grown in swards from 30 to 70% and in standard pots from 10 to 35%. There were mortalities among both inoculated and control plants grown under 125 f.c. : in swards, 80–90% of inoculated plants and 30–40% of control plants died, whereas in standard pots 20–30% of inoculated plants and only occasional control plants died. The data show that environmental conditions favourable for the development of the disease were unfavourable for growth of control plants.

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.

Corrigendum - Humidity, free water and light in relation to development of Kabatiella caulivora (Kirchn.) Karak in Trifolium subterraneum L. cv.Yarloo

1975 ◽  
Vol 26 (3) ◽  
pp. 511
Author(s):  
K Helms
Keyword(s):  
Light Intensity ◽  
Plant Growth ◽  
Free Water ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Disease Development ◽  
Kabatiella Caulivora ◽  
Spread Of Infection ◽  
Moisture Conditions ◽  
And Control

The effects of moisture conditions on disease development and plant growth were examined in subterranean clover plants which were inoculated with K. caulivora 4 weeks after sowing and were maintained after inoculation at 20°C and with a light intensity of 2000 f.c. In plants which received 100% relative humidity (RH) with free water on leaves, for at least 4 days after inoculation, 15–20% of leaves developed lesions within 11 days. In plants which received continuously 90% RH with free water on leaves, or 100% RH without free water on leaves, less than 1.5% of leaves developed lesions within 11 days. There was no evidence of spread of infection in plants maintained for 11 or 25 days after inoculation. The effects of light intensities of 2000, 500 and 125 f.c. on disease development and plant growth were examined in plants which received 100% RH with free water on leaves and were grown for 25 days after inoculation, either in simulated swards or in standard pots. In most treatments a reduction in light intensity from 2000 to 500 f.c. reduced the growth of plants but had no effect on the percentage of diseased leaves, whereas a reduction in light intensity from 500 to 125 f.c. reduced growth and increased the percentage of diseased leaves of plants grown in swards from 30 to 70% and in standard pots from 10 to 35%. There were mortalities among both inoculated and control plants grown under 125 f.c. : in swards, 80–90% of inoculated plants and 30–40% of control plants died, whereas in standard pots 20–30% of inoculated plants and only occasional control plants died. The data show that environmental conditions favourable for the development of the disease were unfavourable for growth of control plants.

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