Fusarium Resistance Research Articles

In vitro techniques for selecting wheat (Triticum aestivum L.) for Fusarium-resistance. I. Double-layer culture technique

Calluses of spring and winter wheats (Triticum aestivum L.) were selected for Fusarium resistance in vitro, using the double-layer culture technique. Potato-dextrose agar medium in vials was inoculated with mycelia of Fusarium graminearum and F. culmorum. After one week, fungal cells were killed by autoclaving and the agar medium containing the thermostable toxic metabolites was overlayered with MS callus-growing medium. Later, wheat calluses were placed on the upper medium for 4–5 weeks, and from the surviving calluses plants were regenerated. R2 seedling populations from self-fertilized R1 plants of 4 varieties were tested for Fusarium resistance by artificial infections in the greenhouse, and 3% of the regenerated R2 plants have been found to be more resistant than the original cultivars.

RFLP mapping of I1, a new locus in tomato conferring resistance against Fusarium oxysporum f. sp. lycopersici race 1

The inheritance and linkage relationships of a gene for resistance to Fusarium oxysporum f. sp. lycopersici race 1 were analyzed. An interspecific hybrid between a resistant Lycopersicon pennellii and a susceptible L. esculentum was backcrossed to L. esculentum. The genotype of each backcross-1 (BC1) plant with respect to its Fusarium response was determined by means of backcross-2 progeny tests. Resistance was controlled by a single dominant gene, I1, which was not allelic to I, the traditional gene for resistance against the same fungal pathogen that was derived from L. pimpinellifolium. Linkage analysis of 154 molecular markers that segregated in the BC1 population placed I1 between the RFLP markers TG20 and TG128 on chromosome 7. The flanking markers were used to verify the assignment of the I1 genotype in the segregating population. The results are discussed with reference to the possibility of cloning Fusarium resistance genes in tomato.

Diallel analysis of resistance to head blight caused by Fusarium culmorum in winter wheat

Ten homozygous winter wheat genotypes representing different levels of resistance to Fusarium head blight were crossed in all possible combinations excluding reciprocals. Parents, F1 and F2 were inoculated with one pathogenic strain of Fusarium culmorum. Data for head blight, observed 21 days after first inoculation (OBS-2), and for the area under the disease progress curve, based on observations 14, 21 and 28 days after first inoculation (AUDPC), were analyzed. The contrast between parents and F1 crosses indicated dommance effects of the resistance genes. Diallel analysis according to Griffing's Method 4, Model 1 showed significant general combining ability (GCA) effects for both F1 and F2; specific combining ability effects were not significant. With the exception of one genotype for which general performance for Fusarium resistance was not in agreement with its GCA, the resistance to F. culmorum was uniformly transmitted to all offspring, and the parents can be described in terms of GCA. It is suggested that in the progenies with one of the awned lines as parent, one resistance gene was linked with the gene coding for presence of awns, located on chromosome 4B. A single observation date, taken at the right time, was as effective in assessing resistance as the AUDPC.

Factors influencing establishment inVicia faba

SUMMARYTannin-containing and tannin-free members of two pairs of near-isogenic lines ofVicia fabawere studied in glasshouse experiments at Plant Breeding International Cambridge in 1989 to determine the cause of poor establishment of tannin-free lines in the field. Tests in field soils demonstrated marked differences in disease severity and growth, the tannin-containing lines being the more resistant toFusarium culmorumandF. solani, the principal pathogens isolated. Susceptibility was not attributable to testa damage in tannin-free lines. In further tests on a range of varieties, some tanninfree and low-tannin, coloured-flowered varieties were as resistant as standard high-tannin lines. The results indicate that it should be possible to select for resistance to seedling infection and to subseque1t poor establishment among tannin-free lines and varieties.

The Development of a Host‐Pathogen System for Evaluating Fusarium Resistance in Early Growth Stages of Wheat

AbstractControlled environment studies revealed significant genetic variation in resistance of wheat seedlings to Fusarium culmorum by using a new developed test system which affords a reproducible inoculation and a precise measurement of the infection rate. A nutrient solution and a conidial suspension in a defined amount are added to agar after autoclaving and the germinated seed are incubated under sterile conditions. With this in vitro‐culture technique F. culmorum infected the whole root system of all tested plants during 12 days and caused significant reduction of root and shoot dry weights. Therefore, escape reactions, depending on the different rapidity of root development, were eliminated. The loss of root dry matter ranged from 12 to 89 %, thus allowing a selection for Fusarium resistance even in the early developmental stages of wheat.

Fusarium Root Rot-resistant Snap Bean Breeding Line FR-266

Abstract The ARS/USDA and the Agricultural Experiment Station of Washington State Univ. announce the release of germplasm line, FR (Fusarium Resistant)-266, a bush snap bean (Phaseolus vulgaris L.) line, which is resistant to Fusarium root rot caused by Fusarium solani (Mart.) Appel & Wr. f. sp phaseoli Burkh. Snyd. & Hans. FR-266 also is resistant to bean common mosaic virus (dominant I gene)(l), curly top virus, and is tolerant to white mold caused by Sclerotinia sclerotiorurn (Lib.) deBary. FR-266 is the only known green-podded, white-seeded, bush snap bean line that has this unique combination of multiple disease resistance factors.

Among- and within-population variability for forage yield and Fusarium resistance in birdsfoot-trefoil

Polycross families of birdsfoot-trefoil, Lotus corniculatus L., were evaluated in the greenhouse for number of live plants 120 days after inoculation with Fusarium oxysporum (Schlecht) Snyd. & Hans, and in the field for forage yield and stand scores. The parents of the polycross progenies came from 11 different birdsfoot-trefoil cultivars. The objective of the experiment was to determine relative importance of source population and parents within source population as sources of variability for reaction for F. oxysporum, forage yield, and stand score. Expected values for means of polycross families within source populations and for source populations were expressed in terms of parameters from a previously developed autotetraploid genetic model. All genetic effects were present in the equations, but variation among source populations would be important only if the source populations differed in gene frequencies. Source populations were the only significant source of variation for the number of live plants 120 days after inoculation with F. oxysporum and the stand score. A significant year by source population interaction was observed for total season yield. The correlation between number of live plants in the greenhouse and the stand score was significant. We concluded (i) selection of source population was important when breeding for resistance to F. oxysporum or improved stand but not for total season yield, and (ii) successful breeding for resistance to F. oxysporum would contribute to improved persistence in birdsfoot-trefoil. Key words: Lotus corniculatus L., Fusarium oxysporum, polycross progeny, selection.

Involvement of Ethylene in Herbicide-Induced Resistance toFusarium oxysporumf. sp.melonis

Involvement of Ethylene in Herbicide-Induced Resistance to<i>Fusarium oxysporum</i>f. sp.<i>melonis</i>

Site of Action of Factors for Resistance toFusarium moniliformein Maize

Site of Action of Factors for Resistance to<i>Fusarium moniliforme</i>in Maize

The mechanism of preferential fertilization in tomatoes carrying the I-Allele for fusarium resistance

Preferential fertilization of ovules by male gametes carrying the dominant I allele for Fusarium resistance occurred when heterozygous Ii plants served as male parent. Pollination with a mechanical l:l mixture of I and i pollen gave the normally expected Mendelian ratio. No significant differences were found in vivo in growth rate or in final length of pollen tubes of genotypes I and i. The experiments indicated that preferential fertilization was mainly caused by prepollination events leading to production of unequal amounts of fertile pollen grains of the two types.

Inheritance of Fusarium resistance in a jointless tomato as affected by the X gametophytic factor

Hybridization between tomato with xx and XX gametophytic genotypes exhibited in segregating generations, deviations from the expected monogenic inheritance of Fusarium wilt resistance conditioned by gene I. These deviations resul ted from gametophytic preference, linkage and the presence of modifying loci associated with the gene I. Although information on the inheritance of Fusarium wilt resistance is based on backcross data, information obtained from the pedigree procedure and testcrosses made with BC1S2 plants all supports the presence of modifiers.

Synthesis of a Jointless Fusarium Resistant Strain of Tomato by Circumvention of the X Gametophytic Factor1

Abstract The development of a jointless, Fusarium resistant tomato strain was complicated by a gametophytic factor. The backcross was made using the F1 as the female parent with the recessive parent as the male to eliminate competition. The backcross population was screened for Fusarium resistance. Survivors were selected for the jointless character and selfed to obtain progenies to test for Fusarium resistance. One plant family showing the predicted 4:1 ratio was recovered but no plant family showing the predicted 3:1 ratio was recovered.

Non-random segregation of gene I for Fusarium resistance in the tomato

Significant deviations from the ratios expected, according to the single dominant gene hypothesis for resistance to Fusarium wilt, were found in crosses involving several susceptible and resistant tomato lines. The susceptible class was the deficient one in F2 and F3 populations, as well as in backcrosses in which the heterozygotic resistant F1 served as the male parent. The reciprocal backcross, with the F1 as the female and the homozygous susceptible as the male, gave segregations better approximating or consistent with the single gene hypothesis. Reciprocal F1 and F2 generations did not give any evidence of cytoplasmic effects.

Penetrance of gene I for Fusarium resistance in the tomato

Tomato seedlings were inoculated, from one to ten days after emergence, with the tomato Fusarium wilt fungus race 1. The penetrance of gene I for Fusarium resistance in the homozygous resistant variety Homestead 24 was almost complete. In the F1 (Ii) between Homestead 24 and the susceptible Marmande penetrance was incomplete and ranged between 66.3% and 100% in different experiments. The age of seedlings at time of inoculation did not affect the final percentage of diseased plants while it influenced the nature and the time of appearance of disease symptoms. Possible consequences of incomplete penetrance for the resistance of F1 hybrids are discussed.

Infection of first-year potato seedlings with fusarium solani var. eumartil

The testing of first-year seedlings for fusarium wilt resistance in the greenhouse has proved to be a satisfactory method of eliminating susceptibles. It overcomes the disadvantages of the high expense of growing plants from tubers in the greenhouse and reduces the large number of escapes that often occur in the field. The symptoms of the disease are as clearly defined in the small seedling plants as in plants grown from tubers. Although seedlings of desirable horticultural quality may be lost, the high percentage of infection obtained in all crosses tested to date would indicate that the chances of obtaining resistant seedlings after selection has been made for other characters would be slight. The number of tests to date has been limited but the results indicate that the desirability of parent stock for fusarium resistance can be rapidly determined by this method.