Verticillium dahliae infects over 300 cultivated plants, including strawberry. The fungus destroys vascular tissues causing drought stress resembling foliar symptoms. The outer leaves wilt and turn brown and the inner wilt but remain bluish green. Brownish to bluish black streaks or blotches may also appear on the runners and/or petioles (Bielenin and Meszka, 2009; Meszka, 2013). New roots that grow from the infected crown are often dwarfed with blackened tips. Crowns when cut lengthwise may show blackening or browning of the vascular tissue. Daughter plants attached to the infected mother plants may also exhibit the disease symptoms [Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), 2009]. Infected plants cannot balance their water intake. The fungus also releases toxins causing further damage to leaves (Kiraly et al., 1977). In the case of severe infestation, strawberry plants die (Löckener, 1995).
V. dahliae overwinters in soil and plant debris as a dormant mycelium or black, speck-sized bodies (microsclerotia). Microsclerotia can survive in soil for 12 to 14 years (Bielenin et al., 1998; Wilhelm, 1955). When suitable conditions occur (high humidity and temperature of 23 to 25 °C), these microsclerotia germinate by putting forth one or more thread-like hyphae (Domsch et al., 1980). These hyphae may penetrate the root hairs directly, but more infection can occur through breaks or wounds in rootlets caused by insects, cultivation or transplanting equipment, frost injury, or root-feeding nematodes (OMAFRA, 2009). The severity of infestation depends on susceptibility of the host-plant genotype, source of infection (Harris and Yang, 1996), and environmental factors such as humidity and temperature (Bielenin et al., 1998). According to Gallegos (2011), as low as five microsclerotia per gram of soil can reduce yield of commercial strawberries by 24% and 10 or more from 47% to 63%. Control of verticillium wilt is difficult as a result of wide presence of the fungus in soils (Borecki, 1987) and then high cost of its control. The use of healthy stock plant material and soil disinfection before transplanting are the most common approaches to the controlling the fungus control (Duniway, 2002; Meszka, 2013). Planting cultivars tolerant to verticillium wilt, or with low susceptibility, would be more desirable from economic and environmental points of view. Examples of the currently available germplasm include cultivars Pegasus, Pandora, Calypso, Tango (Simpson et al., 1994), Senga Sengana, Elkat, Elianny, Vima Rina, Albion, Salsa, Evie II, Aga, Fara, Daroyal, Dukat, Filon, Salut, Vikat, Chandler, and Favette (Masny and Żurawicz, 2008, 2009a, 2009b). Shaw et al. (2005) state that plantations with susceptible cultivars can face up to 75% yield losses compared with 7% to 15% for tolerant or low susceptible. This makes expansion of strawberry breeding programs for tolerance to verticillium wilt a top priority to the small fruit industry. Although there are a number of tolerant strawberry cultivars available, none of them is fully resistant to V. dahliae (Bolda and Koike, 2013). Evaluation of candidate parental genotypes such as genetic indicators as general and specific combining ability for the resistance trait will undoubtedly significantly contribute to the efficacy of the breeding programs.
General combining ability of a parental genotype for the quantitative trait of interest describes the ability of that parent to pass the trait at some average level to its half-sib progeny (Baker, 1978; Griffing, 1956a, 1956b). Then, the GCA effect of a parent on a trait is a measure of the additive effect of the parent’s genes on that trait within the gene pool of the parental forms taking part in the planned mating design (Griffing, 1956a, 1956b). GCA of the parents for a trait determines their overall usefulness, with respect to that trait, for creating new cultivars. The most valuable hybrid progeny in terms of quantitative traits can be obtained by crossing parents that exhibit favorable GCA effects for these traits (Masny et al., 2005, 2008, 2009; Yashiro et al., 2002; Żurawicz et al., 2006).
Specific combining ability of a pair of parents for the quantitative trait of interest is the genetic interaction of both parents on that trait, manifested in the full-sib progeny. Therefore, the SCA effect of two parents on a trait is a measure of their genetic interaction effect on that trait and is the result of the non-additive action (dominance and epistasis) of the parents’ genes (Baker, 1978; Griffing, 1956a, 1956b).
Resistance to verticillium wilt is inherited polygenetically and depends on genetic additive effects and dominant effects (Bringhurst et al., 1968; Maas et al., 1989). However, so far combining abilities of strawberry germplasm for tolerance to verticillium wilt have not been comprehensively documented. Evaluation of the GCA and SCA effects of 10 strawberry genotypes used in breeding programs (Capocasa and Mezzetti, 2012; Faedi et al., 2009) was the primary objective of this study.
Bielenin, A., Cieślińska, M. & Łabanowska, B.H. 1998 Atlas chorób i szkodników truskawki. Instytut Sadownictwa i Kwiaciarstwa, Skierniewice, Poland
Bielenin, A. & Meszka, B. 2009 Choroby krzewów owocowych. Plantpress, Krakow, Poland
Bolda, M. & Koike, S. 2013 Verticillium wilt in strawberries: California 2013 update. 6 Aug. 2013. <http://ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=10993>
Borecki, Z. 1987 Nauka o chorobach roślin. Państwowe Wydawnictwo Rolnicze i Leśne, Warsaw, Poland
Bringhurst, R.S., Hansche, P.E. & Voth, V. 1968 Inheritance of verticillium wilt resistance and the correlation of resistance with performance traits Proc. Amer. Soc. Hort. Sci. 92 369 375
Capocasa, F. & Mezzetti, B. 2012 Romina and Cristina: Two new strawberry varieties released by Marche Polytechnic University. VII Intl. Strawberry Symp., Intl. Soc. Hort. Sci., China Agriculture Press, Beijing, China. p. 218 (abstr.)
Domsch, K.H., Gams, W. & Anderson, T.H. 1980 Compendium of soil fungi. 1st Ed. Academic Press, London, UK
Dossett, M., Lee, J. & Finn, C.E. 2008 Genetics and breeding inheritance of phenological, vegetative and fruit chemistry traits in black raspberry J. Amer. Soc. Hort. Sci. 133 408 417
Dressler, A., Scheewe, P., Lentzsch, P. & Olbricht, K. 2010 Evaluation of strawberry cultivars for resistance to Verticillium dahliae Kleb, p. 350–352. In: Ecofruit Conf. Proc. 2010. 6 Aug. 2013. <http://www.ecofruit.net/2010>
Faedi, W., Baruzzi, G., Lucchi, P. & Sbrighi, P. 2009 Monografia di cultivar di fragola. VII Convegno Nazionale La Fragola: Presente e Futuro, Marsala, Italy, 25–30 Mar. 2009. Regione Siciliana Assessorato Agricoltura e Foreste, Rome, Italy
Gallegos, L. 2011 Effects of a range of inoculum densities of Verticillium dahliae on strawberry in California. MS thesis, University of California, Davis, CA
Garretsen, F. & Keuls, M. 1978 A general method for the analysis of genetic variation in complete and incomplete diallels and North Carolina II (NC II) designs. Part II. Procedures and general formulas for the fixed model Euphytica 27 49 68
Giménez, G. & Ballington, J.R. 2002 Inheritance of resistance to Colletotrichum acutatum Simmonds on runners of garden strawberry and its backcrosses HortScience 37 686 690
Harris, D.C. & Yang, J.R. 1996 The relationship between the amount of Verticillium dahliae in soil and the incidence of strawberry wilt as a basis for disease risk prediction Plant Pathol. 45 106 114
Hortyński, J.A. 1987 Dziedziczenie niektórych cech ilościowych truskawki (Fragaria × ananassa Duch.). Metody i problemy oszacowań. Monografie i rozprawy. Akademia Rolnicza, Lublin, Poland
Kiraly, Z., Klement, Z., Solymosy, F. & Voros, J. 1977 Fitopatologia: Wybór metod badawczych. Państwowe Wydawnictwo Rolnicze i Leśne, Warsaw, Poland
Maas, J.L., Galletta, G.J. & Draper, A.D. 1989 Resistance in strawberry to races of Phytophthora fragariae and to isolates of Verticillium from North America Acta Hort. 265 521 526
Masny, A., Mądry, W. & Żurawicz, E. 2005 Combining ability analysis of fruit field and fruit quality in ever-bearing strawberry cultivars using an incomplete diallel cross design J. Fruit Ornamental Plant Res. 13 5 17
Masny, A., Mądry, W. & Żurawicz, E. 2008 Combining ability for important horticultural traits in medium- and late-maturing strawberry cultivars J. Fruit Ornamental Plant Res. 16 133 152
Masny, A., Mądry, W. & Żurawicz, E. 2009 General combining ability of ten strawberry cultivars for ripening time, fruit quality and resistance to main leaf diseases under Polish conditions Acta Hort. 842 601 604
Masny, A. & Żurawicz, E. 2008 Podatność nowych odmian deserowych truskawki na wertycyliozę w warunkach polowych Zeszyty Naukowe Instytutu Sadownictwa i Kwiaciarstwa 16 249 255
Masny, A. & Żurawicz, E. 2009a Porażenie wybranych odmian truskawki (Fragaria × ananassa) przez Verticillium dahliae 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 Verticillium dahliae Kleb. w uprawach truskawki w Polsce oraz możliwości ich ochrony przed wertycyliozą. Monografie i Rozprawy. Instytut Ogrodnictwa, Skierniewice, Poland
Olbricht, K. & Hanke, M.V. 2008 Strawberry breeding for disease resistance in Dresden, p. 144–147. In: Boos, M. (ed.). Ecofruit—13th Intl. Conf. on Cultivation Technique and Phytopathological Problems in Organic Fruit-Growing, 18–20 Feb. 2008, Weinsberg, Germany. 10 Feb. 2014. <http://orgprints.org/13660/>
Ontario Ministry of Agriculture, Food and Rural Affairs 2009 Verticillium wilt. 6 Aug. 2013. <http://www.omafra.gov.on.ca/IPM/english/strawberries/diseases-and-disorders/verticillium-wilt.html>
Shaw, D.V., Gordon, T.R., Larson, K.D. & Kirkpatrick, S.C. 2005 The effect of Verticillium infection in runner plant propagation nurseries on resistant and susceptible strawberry genotypes J. Amer. Soc. Hort. Sci. 130 707 710
Shaw, D.V., Gubler, W.D., Larson, K.D. & Hansen, J. 1996 Genetic variation for field resistance to Verticillium dahliae evaluated using genotypes and segregating progenies of California strawberries J. Amer. Soc. Hort. Sci. 121 625 628
Simpson, D.W., Bell, J.A. & Harris, D.C. 1994 Breeding for resistance to fungal diseases in strawberry, p. 63–66. In: Schmidt, H. and M. Kellerhaus (eds.). Progress in temperate fruit breeding. Kluwer, Dordrecht, The Netherlands
Yashiro, K., Tomita, K. & Ezura, H. 2002 Is it possible to breed strawberry cultivars which confer firmness and sweetness? Acta Hort. 567 223 225
Żebrowska, J.I. 2011 Efficacy of resistance selection to verticillium wilt in strawberry (Fragaria x ananassa Duch.) tissue culture Acta Agrobotanica 64 3 12
Żurawicz, E. 1990 Odziedziczalność najważniejszych cech użytkowych truskawki (Fragaria × ananassa Duch.). Monografie i rozprawy. Instytut Sadownictwa i Kwiaciarstwa, Skierniewice, Poland
Żurawicz, E. & Masny, A. 2005 Uprawa truskawek w polu i pod osłonami. Plantpress, Krakow, Poland
Żurawicz, E., Masny, A. & Mądry, W. 2006 Usefulness of selected strawberry (Fragaria × ananassa) genotypes for breeding late ripening cultivars Acta Hort. 708 501 505