Plant breeders must be aware of sources of resistance to pathogens that affect their crops. Fusarium wilt caused by Fusarium oxysporum Schl. f. sp. pisi Snyd. & Hans. is a fungal disease that affects peas and is important worldwide. Resistance to the different races of the pathogen has been identified in adapted germplasm and from specific accessions in the United States World Collection of peas (Pisum sativum L.). The goal of this study was to evaluate the resistance to fusarium wilt race 2 in the Pisum core collection. Of the 452 accessions screened, 62 (14%) were resistant. The resistant accessions included accessions from P.s. ssp. elatius that were collected from 24 different countries. The wide distribution of resistance around the world precludes the identification of any single country or region as a source of resistance. Of the 62 accessions resistant to race 2, 39 are also resistant to race 1 based on data obtained from GRIN. One of the wild progenitors, PI 344012, possessed resistance to races 1 and 2.
A chitinase gene (pcht28), isolated from Lycopersicon chilense, was transferred into `Joliette' strawberry using a stipule regeneration method and Agrobacterium-mediated gene transfer technique. Stipules showed a high rate of shoot regeneration (>90%) through direct or indirect organogenesis. Stipules were cocultured with a transformation plasmid in which pcht28 was under the control of the CAMV 35S promoter. A high tendency in production of chimaeric shoots was observed. Shoots which did not show any sign of bleaching after several subcultures in kanamycin containing medium were considered as stable transformants. These shoots were successfully rooted in the presence of 50 μg·mL-1 kanamycin. Transgenic nature of the plants was confirmed by PCR as well as Southern blot analysis. Constitutive expression of the chitinase gene was demonstrated by Northern analysis. In growth chamber studies, the transgenic strawberry plants which expressed pcht28 had significantly higher resistance to Verticillium dahliae as compared to nontransgenic controls. These results demonstrate that pcht28 plays a role in defense against this fungal disease in strawberry.
Eastern filbert blight is an economically significant disease in European hazelnut (Corylus avellana L.) production in the United States. Since genetic resistance is the only viable disease control strategy to this fungal disease caused by Anisogramma anomala (Peck) E. Müller, greenhouse and field screening of germplasm was undertaken to study the inheritance from known resistant sources and to identify new sources for inclusion in the breeding program. We confirmed that `Gasaway' resistance to this disease is conferred by a single dominant gene. No major gen was identified in the field-resistant cultivar Gem. Representatives of six Corylus species were screened to identify new resistant germplasm. Corylus cornuta Marshall var. cornuta, C. cornuta var. californica (A.DC.) Sharp, C. heterophylla Fischer, and C. sieboldiana Blume were highly resistant, as were most C. americana Marshall genotypes and one C. colurna L. clone tested, but C. jacquenontii Decaisne was highly susceptible. In several cases, hybrids of these species with susceptible C. avellana were also resistant. These new sources of resisstance are being incorporated in the resistance breeding effort.
Eastern filbert blight (EFB) is a serious fungal disease of european hazelnut (Corylus avellana) in North America. The causal agent is the pyrenomycete Anisogramma anomala, which is native in the eastern United States where it occasionally produces small cankers on the wild american hazelnut (C. americana). However, most commercial cultivars of european hazelnut are susceptible. Infection leads to perennial cankers, girdling of branches, and premature tree death. Cultural practices including scouting, pruning out infected branches, and fungicide applications are recommended to slow disease spread but are expensive and not completely effective. EFB resistance from ‘Gasaway’ is conferred by a dominant allele at a single locus and has been extensively used in the Oregon State University hazelnut breeding program, but there is concern that this resistance could be overcome by isolates now present in the eastern United States or that a new race of the pathogen could arise in Oregon. Segregation for EFB resistance from ‘Uebov’, a new source from Serbia, was studied in three progenies by a combination of structure exposure and greenhouse inoculation. The frequency of resistant seedlings following structure exposure was about 20% in all three progenies. The ratios failed to fit the expected 1:1 ratio but did fit a ratio of 1 resistant:3 susceptible, which would be expected if resistance were conferred by dominant alleles at two independent loci. Seedlings from a cross of susceptible selection OSU 741.105 and ‘Uebov’ were used to study correlation of disease response and presence of alleles at microsatellite marker loci. Resistance was highly correlated with the presence of alleles at marker loci on linkage group 6 (LG6), and these markers also showed segregation distortion. We conclude that EFB resistance from ‘Uebov’ maps to a single locus on LG6 in the same region as resistance from ‘Gasaway’, although only about 20% of the seedlings are resistant because of segregation distortion. ‘Uebov’ has large, well-filled, round nuts and is suitable as a parent in breeding for the in-shell market, but its low nut yields and a high frequency of shells with split sutures are the drawbacks. Its use would expand options for breeding and ‘Uebov’ resistance could be combined with other resistance alleles with an expectation of more durable EFB resistance. Durable resistance would not only sustain the hazelnut industry in Oregon but would also allow expansion of plantings to new areas.
are also discussed. Methods and Materials Experimental material. Ten parental gooseberry cultivars ( Table 1 ), originating from different countries and differing in horticultural traits of plant and fruit morphology and reaction to fungal diseases
Zeszyty Problemowe Postępów Nauk Rolniczych 539 483 490 Masny, A. Żurawicz, E. 2009b Yielding of new dessert strawberry cultivars and their susceptibility to fungal diseases in Poland J. Fruit Ornamental Plant Res. 17 191 202 Meszka, B. 2013 Występowanie
beneficial effects of E. festucae fungal endophyte infection on strong creeping red fescue regarding insect and fungal disease tolerance are well established ( Bonos et al., 2005 ; Clarke et al., 2006 ; Saha et al., 1987 ; Yue et al., 2000 ). However
et al., 2015 ). Phytophthora sojae isolates were preserved at 12 °C at the Mycology and Plant Fungal Disease Laboratory of Anhui Agricultural University (Hefei, China). The P. sojae strains used in this study were cultured on 10% V 8 medium at 25
host plant resistance to a fungal disease is generally affected by environmental factors such as temperature, humidity, and soil pH. In the clubroot disease evaluation, both the humidity level in the soil and the temperature can influence the pathogen
is of global significance and is one of the most serious fungal diseases affecting apple in Japan ( Saito et al., 2001 ; Sawamura, 1990 ; Sekiguchi, 1976 ), Korea ( Lee and Lee, 1972 ), the United States ( Filajdic and Sutton, 1991 ), and China