Much of the highbush blueberry crop goes to fresh market and postharvest decay is an ongoing problem. The most important postharvest disease of blueberry is anthracnose fruit rot [causal agent Colletotrichum acutatum and, in some growing regions, C. gloeosporioides (Penz.) Penz. and Sacc.]. Losses resulting from anthracnose preharvest are typically 3% to 5%, and postharvest losses can reach 100% (Milholland, 1995).
Highbush blueberry fruit typically becomes infected in the field while still green. Spores germinate on infected fruit, form appressoria, and then become dormant until the fruit ripens (Daykin and Milholland, 1984). Highbush blueberry cultivars have shown a wide range of susceptibility to this disease (Polashock et al., 2005) and the mechanism of disease resistance among cultivars is not known.
Aromatic volatiles contribute to the aroma and flavor of fruit and vegetables, including highbush blueberry (Forney, 2001). Emitted volatiles from highbush blueberry fruit are primarily aldehydes and terpenes (Baloga et al., 1995; Overton and Manura, 1999). Aldehydes, organic compounds containing a terminal carbonyl (-CHO) group, are often derived from lipid peroxidation (Latrasse, 1991). Terpenes, primarily plant hydrocarbons formed from linked isoprene (C5H8) units, are derived from the mevalonate and methylerythritol pathways and specific terpene synthases (Dudareva et al., 2004). These and other volatiles emitted from highbush blueberry and other fresh produce are active against bacteria, fungi, and viruses (Cowan, 1999; Dorman and Deans, 2000; Gardini et al., 2001; Utama et al., 2002). The incorporation of high concentrations of various antimicrobial volatiles, including hexanal and trans-2-hexenal, into the storage atmosphere of fresh produce has been shown to reduce postharvest decay (Corbo et al., 2000; Lanciotti et al., 1999). Most, if not all, terpenes emitted from highbush blueberry have antifungal activities and include 1,8-cineole (Tabanca et al., 2006; Wilson et al., 1997), caryophyllene (Raintree Nutrition Inc., 2004), cadinene (Song et al., 2007), α-farnesene (Govinden-Soulange et al., 2004), 2- and 3-carene (Archbold et al., 1997; Cavaleiro et al., 2006; Himejima et al., 1992), limonene (Archbold et al., 1997; Himejima et al., 1992; Wilson et al., 1997), linalool (Carson and Riley, 1995; Fraternale et al., 2004; Plotto et al., 2003), terpinolene (Himejima et al., 1992), α-terpineol (Carson and Riley, 1995; Tepe et al., 2004), and α-terpinyl acetate (Peana et al., 1999). 8-Hydroxylinalool, another volatile emitted from highbush blueberry fruit, may have antifungal activity because oxygenated terpenes generally have more antifungal activity than nonoxygenated ones (Caccioni and Guizzardi, 1994; Knobloch et al., 1989). In addition, several essential oils with antifungal activities have as their major components the same terpenes as those emitted from highbush blueberry (Al-Howiriny, 2003; Sipailiene et al., 2006; Wilson et al., 1997). A few essential oils have been tested and shown to have specific antifungal activity against Colletotrichum Corda in Strum. species, including C. acutatum (Demirci et al., 2006; Tabanca et al., 2006, 2007).
Preliminary analysis of highbush blueberry volatiles showed that cultivars ‘Duke’ and ‘Bluecrop’ had similar volatile profiles, but ‘Duke’ had higher concentrations of emitted antimicrobial volatiles (N. Vorsa, personal communication). These two cultivars were shown to have significant differences in anthracnose fruit rot resistance with ‘Duke’ being more resistant (Polashock et al., 2005). In addition to direct antimicrobial activities, trans-2-hexenal and other emitted volatiles may induce expression of host defense-related genes (Bate and Rothstein, 1998; Ding et al., 2002).
Based on the known presence of these antimicrobial volatiles in highbush blueberry and the differences in volatile concentrations of ‘Duke’ and ‘Bluecrop’, we hypothesized that volatiles naturally produced in highbush blueberry reduce postharvest decay caused by C. acutatum. To test this hypothesis, 10 (in 2004) and six (in 2005) highbush blueberry cultivars spanning the range from very susceptible to very resistant were surveyed for qualitative and quantitative differences in fruit volatile emissions when the fruit were harvested and kept in air at 20 °C for 0 to 6 d (to simulate market shelf conditions). Because many of the antimicrobial volatiles are produced when plant tissues are wounded (Chappell, 1995; Hatanaka, 1993; Mari and Guizzardi, 1998), we also measured volatile emissions from whole fruit inoculated with anthracnose (i.e., pathogen “wounded” as fungal hyphae penetrate the fruit surface) and from fruit extracts prepared from both noninoculated and C. acutatum-inoculated fruit.
Primary objectives were to: 1) determine the quantitative and qualitative differences in fruit volatile emissions across representative highbush blueberry cultivars with varying susceptibility to anthracnose fruit rot, 2) determine the qualitative and quantitative changes in fruit volatile emissions when fruit were kept in air at 20 °C for varying times postharvest, and 3) investigate if known fruit rot susceptibilities are determined by differences in fruit volatile emissions. Secondary goals were to 1) determine if volatiles, especially those known to be antimicrobial, could be induced by inoculation with anthracnose spores; 2) determine what genetic, environmental, and other factors affected fruit volatile emissions and to what degree; and 3) characterize correlations among volatiles.
Al-Howiriny, T.A. 2003 Composition and antimicrobial activity of the essential oil of Salvia lanigera Pakistan J. Biol. Sci. 6 133 135
Anderson, R.A., Hamilton-Kemp, T.R., Hildebrand, D.F., McCracken C.T. Jr, Collins, R.W. & Fleming, P.D. 1994 Structure–antifungal activity relationships among volatile C6 and C9 aliphatic aldehydes, ketones, and alcohols J. Agr. Food Chem. 42 1563 1568
Archbold, D.D., Hamilton-Kemp, T.R., Barth, M.M. & Langlois, B.E. 1997 Identifying natural volatile compounds that control gray mold (Botrytis cinerea) during postharvest storage of strawberry, blackberry, and grape J. Agr. Food Chem. 45 4032 4037
Azaz, D., Demirci, F., Satil, F., Kurkcuoglu, M. & Baser, K.H.C. 2002 Antimicrobial activity of some Satureja essential oils Zeitschrift fur Naturforschung 57c 817 821
Baloga, D.W., Vorsa, N. & Lawter, L. 1995 Dynamic headspace gas chromatography–mass spectrometry analysis of volatile compounds from wild diploid blueberry species 235 247 Rouseff R.L. & Leahy M.M. Fruit flavors. Amer. Chem. Soc Chicago
Bate, N.J. & Rothstein, S.J. 1998 C6-volatiles derived from the lipoxygenase pathway induce a subset of defense-related genes Plant J. 16 561 569
Burnham, K.P. & Anderson, D.A. 1998 Model selection and inference: A practical information-theoretic approach Springer-Verlag New York
Buttery, R.G. & Ling, L.C. 1993 Volatile components of tomato fruit and plant parts: Relationship and biogenesis 23 34 Teranishi R., Buttery R. & Sugisawa H. Bioactive volatile compounds from plants Amer. Chem. Soc Washington, DC
Caccioni, D.R.L. & Guizzardi, M. 1994 Inhibition of germination and growth of fruit and vegetable post-harvest pathogenic fungi by essential oil components J. Essential Oil Res. 6 173 179
Carson, C.F. & Riley, T.V. 1995 Antimicrobial activity of the major components of the essential oil of Melaleuca alternifolia J. Appl. Bacteriol. 78 264 269
Cavaleiro, C., Pinto, E., Goncalves, M.J. & Salgueiro, L. 2006 Antifungal activity of Juniperus essential oils against dematophyte, Aspergillus and Candida strains J. Appl. Microbiol. 100 1333 1338
Corbo, M.R., Lanciotti, R., Gardini, F., Sinigaglia, M. & Guerzoni, M.E. 2000 Effects of hexanal, trans-2-hexenal, and storage temperature on shelf life of fresh sliced apples J. Agr. Food Chem. 48 2401 2408
Delaquis, P.J., Stanich, K., Girard, B. & Mazza, G. 2002 Antimicrobial activity of individual and mixed fractions of dill, cilantro, coriander and eucalyptus essential oils Int. J. Food Microbiol. 74 101 109
DeMarsay, A. 2005 Anthracnose fruit rot of highbush blueberry: Biology and epidemiology Rutgers, The State University of New Jersey New Brunswick PhD Diss
Demirci, B., Baser, K.H., Tabanca, N. & Wedge, D.E. 2006 Characterization of volatile constituents of Haplopappus greenei and studies of the antifungal activity against phytopathogens J. Agr. Food Chem. 54 3146 3150
Ding, C.K., Wang, C.Y., Gross, K.C. & Smith, D.L. 2002 Jasmonate and salicylate induce the expression of pathogenesis-related protein genes and increase resistance to chilling injury in tomato fruit Planta 214 895 901
Dorman, H.J.D. & Deans, S.G. 2000 Antimicrobial agents from plants: Antibacterial activity of plant volatile oils J. Appl. Microbiol. 88 308 316
Fraternale, D., Ricci, D., Epifano, F. & Curini, M. 2004 Compositional and antifungal activity of two essential oils of Hyssop (Hyssopus officinalis L.) J. Essential Oil Res. 16 617 622
Gardini, F., Lanciotti, R. & Guerzoni, M.E. 2001 Effect of trans-2-hexenal on the growth of Aspergillus flavus in relation to its concentration, temperature and water activity Lett. Appl. Microbiol. 33 50 55
Govinden-Soulange, J., Magan, N., Gurib-Fakim, A., Gauvin, A., Smadja, J. & Kodja, H. 2004 Chemical composition and in vitro antimicrobial activities of the essential oils from endemic Psiadia species growing in Mauritius Biol. Pharmaceutical Bul. 27 1814 1818
Hamilton-Kemp, T.R., McCrackin C.T. Jr, Loughrin, J.H., Anderson, R.A. & Hildebrand, D.F. 1992 Effects of some natural volatile compounds on the pathogenic fungi Alternaria alternata and Botrytis cinerea J. Chem. Ecol. 18 1083 1091
Himejima, M., Hobson, K.R., Otsuka, T., Wood, D.L. & Kubo, I. 1992 Antimicrobial terpenes from oleoresins of Ponderosa pine tree Pinus ponderosa: A defense mechanism against microbial invasion J. Chem. Ecol. 18 1809 1818
Knobloch, K., Pauli, A., Iberl, B., Weis, N. & Weigand, H. 1989 Antibacterial and antifungal properties of essential oil components J. Essential Oil Res. 1 119 128
Lambert, R.J.W., Skandamis, P.N., Coote, P.J. & Nychas, G.-J.E. 2001 A study of the minimum inhibitory concentration and mode of action of oregano essential oil, thymol and carvacrol J. Appl. Microbiol. 91 453 462
Lanciotti, R., Corbo, M.R., Gardini, F., Sinigaglia, M. & Guerzoni, M.E. 1999 Effect of hexanal on the shelf life of fresh apple slices J. Agr. Food Chem. 47 4769 4776
Mari, M. & Guizzardi, M. 1998 The postharvest phase; emerging technologies for the control of fungal diseases Phytoparasitica 26 59 66
Milholland, R.D. 1995 Anthracnose fruit rot (ripe rot) 17 Caruso F.L. & Ramsdell D.C. Compendium of blueberry and cranberry diseases American Phytopathological Society St. Paul, MN
Overton, S. & Manura, J.J. 1999 Volatile organic composition in blueberries 27 Apr. 2006 <http://www.sisweb.com/referenc/applnote/app-43.htm>.
Peana, A.T., Moretti, M.D.L. & Juliano, C. 1999 Chemical composition and antimicrobial action of the essential oils of Salvia desoleana and S. sclarea Planta Med. 65 752 754
Plotto, A., Roberts, D.D. & Roberts, R.G. 2003 Evaluation of plant essential oils as natural postharvest disease control of tomato (Lycopersicon esculentum) Acta Hort. 628 737 741
Polashock, J.J., Ehlenfeldt, M.K., Stretch, A.W. & Kramer, M. 2005 Anthracnose fruit rot resistance in blueberry cultivars Plant Dis. 89 33 38
Raintree Nutrition Inc 2004 Biological activities for compounds of jatoba (Hymenaea courbaril) 27 Apr. 2006 <http://www.rain-tree.com/jatoba-activity.pdf>.
Saftner, R.A. 1999 The potential of fruit coating and film treatments for improving the storage and shelf-life qualities of ‘Gala’ and ‘Golden Delicious’ apples J. Amer. Soc. Hort. Sci. 124 682 689
Saftner, R.A., Abbott, J.A., Conway, W.S., Barden, C.L. & Vinyard, B.T. 2002 Instrumental and sensory quality characteristics of ‘Gala’ apples in response to prestorage heat, controlled atmosphere, and air storage J. Amer. Soc. Hort. Sci. 127 1006 1012
Sipailiene, A., Venskutonis, P.R., Beranauskiene, R. & Sarkinas, A. 2006 Antimicrobial activity of commercial samples of thyme and marjoram oils J. Essential Oil Res. 18 1 7
Song, L., Ding, J.Y., Tang, C. & Yin, C.H. 2007 Compositions and biological activities of essential oils of Kadsura longepedunculata and Schisandra sphenanthera Amer. J. Chin. Med. 35 353 364
Tabanca, N., Demirci, B., Baser, K.H., Aytac, Z., Ekici, M., Khan, S.I., Jacob, M.R. & Wedge, D.E. 2006 Chemical composition and antifungal activity of Salvia macrochlamys and Salvia recognita essential oils J. Agr. Food Chem. 54 6593 6597
Tabanca, N., Demirci, B., Baser, K.H., Mincsovics, E., Khan, S.I., Jacobs, M.R. & Wedge, D.E. 2007 Characterization of volatile constituents of Scaligeria tripartite and studies on the antifungal activity against phytopathogenic fungi J. Chromatogr. B 850 221 229
Tepe, B., Daferera, D., Sökmen, M., Polissiou, M. & Sökmen, A. 2004 In vitro antimicrobial and antioxidant activities of the essential oils and various extracts of Thymus eigii M. Zohary et P.H. Davis J. Agr. Food Chem. 52 1132 1137
Utama, I.M.S., Wills, R.B.H., Ben-Yehoshua, S. & Kuek, C. 2002 In vitro efficacy of plant volatiles for inhibiting the growth of fruit and vegetable decay microorganisms J. Agr. Food Chem. 50 6371 6377
Wilson, C.L., Solar, J.M., El Ghaouth, A. & Wisniewski, M.E. 1997 Rapid evaluation of plant extracts and essential oils for antifungal activity against Botrytis cinerea Plant Dis. 81 204 210
Zeringue, H.J., Brown, R.L., Neucere, J.N. & Cleveland, T.E. 1996 Relationships between C6-C12 alkanal and alkenal volatile contents and resistance of maize genotypes to Aspergillus flavus and aflatoxin production J. Agr. Food Chem. 44 403 407