EFFECTS OF ABA ON BERRY PHYSIOLOGY, QUALITY, AND POSTHARVEST STORAGE OF CRIMSON SEEDLESS TABLE GRAPES

Transcription

1 25 EFFECTS OF ABA ON BERRY PHYSIOLOGY, QUALITY, AND POSTHARVEST STORAGE OF CRIMSON SEEDLESS TABLE GRAPES Matthew Fidelibus, Cecilia Peppi, and Kimberley Cathline. Department of Viticulture and Enology, University of California-Davis, One Shields Ave, Davis, CA 95616, USA ABSTRACT Good berry color is an important characteristic of quality table grapes but the grapes are typically grown in warm climate regions where they are exposed to high temperatures during the ripening period, which inhibits berry coloring. Others have shown that the natural plant hormone abscisic acid (ABA) accumulates in berry skins at the onset of ripening, and application of ABA at that time may hasten coloring. These observations prompted several studies to determine the effects of the plant growth regulator ProTone, the active ingredient of which is ABA, on Crimson Seedless grapes. Using this formulation of ABA, we found that application at veraison rapidly upregulated expression of a critical gene in the anthocyanin biosynthesis pathway, and the berries colored soon thereafter. Crimson Seedless was responsive to ABA at veraison, and for several weeks thereafter. Efficacy generally improved with the quantity of ABA applied and coverage of the clusters. The most striking effect of treatment was improved berry color, but sometimes ABA also increased berry size, decreased acidity, and resulted in some berry softening. In a post-harvest study, treatment improved appearance, perhaps because the treated fruit colored more quickly, and therefore were harvested sooner, than non-treated fruit. INTRODUCTION Table grapes are generally grown in warm-climate regions where high temperatures inhibit anthocyanin accumulation, thereby preventing adequate color development of some red and black fruited grapes (Peppi et al. 2006). Common table grape cultural practices, including the use of vigorous rootstocks (Hashim, personal communication), and the application of gibberellic acid (GA 3 ), forchlorfenuron (CPPU), or both, to increase berry size, may further suppress berry color (Peppi and Fidelibus 2008). For several decades, table grape growers have relied on ethephon applied at veraison, 10-20% berry color, to improve berry color (Szyjewicz et al. 1984, Greyling 2007), but the results are often dissatisfying and, recently, the European Union has expressed concern about ethephon residues on grapes and other fruits. Moreover, late or excessive applications of ethephon can result in soft berries with a poor shelf life (Greyling 2007). Thus, there has been a need for an alternative table grape coloring agent. ABA STIMULATES ANTHOCYANIN ACCUMULATION IN SOME GRAPE TISSUES It has been known for decades that ABA naturally accumulates in grape skins at the onset of ripening, a time when anthocyanins and other phenolic compounds also increase (Coombe and Hale, 1973). This naturally led to the hypothesis that ABA stimulates anthocyanin accumulation, 30

2 and Pirie and Mullins (1976) confirmed that the feeding of excised grape berries with ABA and sucrose independently and synergistically increased anthocyanin content in skins from excised grape berries. Abscisic acid also stimulated anthocyanin accumulation in cultured grape leaf discs, and was more effective than ethephon at enhancing pigment accumulation in the leaf disc system (Pirie and Mullins, 1976). Further studies showed that exogenous application of ABA to grapes also enhanced anthocyanin accumulation (Kataoka et al., 1982; Lee and Tomana, 1980; Lee et al., 1997; Matsushima et al., 1989), even under high temperature regimes that reduced the pigment accumulation in untreated grapes (Tomana et al., 1979). Jeong et al. (2004) provided a physiological basis for ABA activity by showing that the hormone stimulated the accumulation of mrna of several genes involved in anthocyanin biosynthesis including that coding for the UDP-glucose: flavonoid 3-O-glucosyltransferase (UFGT) enzyme that catalyzes a critical step in anthocyanin biosynthesis in grape. Increased UFGT mrna levels were noted two to four weeks after application of ABA (Jeong et al., 2004). Together, these studies suggested that ABA might be a useful active ingredient in a plant growth regulator intended as a coloring agent of grapes, but the high cost of ABA prohibited such uses, and ABA was never tested on internationally important seedless or seeded table grape cultivars. THE DEVELOPMENT OF ABA AS AN AGROCHEMICAL Several years ago, ABA production methods improved such that S-ABA could considered for potential use as an agrochemical. Thus, Valent BioSciences developed a formulated product containing S-ABA, and we tested it on Flame Seedless, Redglobe and Crimson Seedless, table grapes grown in the San Joaquin valley of California. Different ABA concentrations and application times were tested and fruits were evaluated for maturity, firmness, anthocyanins and color. The most striking effect of ABA was an improvement in berry color, with treatments generally having little if any effect on soluble solids or titratable acidity (Peppi et al., 2006, 2007, 2008). For Flame Seedless (Peppi et al. 2006) and Redglobe (Peppi et al., 2007), ABA concentrations around 300 mg/l applied at or shortly after veraison were the most effective at increasing skin anthocyanin content and red berry color. Similarly, the color of Crimson Seedless which is particularly resistant to coloring, was improved by ABA applications between 150 and 300 mg/l at or after veraison (Peppi et al., 2008; Figure 1). Grapes treated with ABA at veraison colored more quickly than those treated with ethephon, allowing them to be harvested sooner (Cantin et al. 2007), a finding that was confirmed by others (Lurie et al. 2009). The appearance of grapes treated with ABA was superior to that of non-treated grapes or grapes treated with ethephon, even after weeks of postharvest cold storage (Cantin et al. 2007). Forchlorfenuron (CPPU) can increase berry size, a desirable response, but it also suppresses color development, an undesirable side effect that limits its use on red and black table grapes. Flame Seedless is particularly sensitive to CPPU-induced color deficiency, therefore it was of interest to evaluate the effect of CPPU and ABA on the fruit quality. Application at fruit set of 8 g/acre of CPPU increased berry size but also delayed maturity and reduced color. Clusters treated with CPPU and ABA (300 or 600 mg/l at veraison) had higher soluble solids, lower acidity, higher anthocyanins and better color than clusters treated only with CPPU (Figure 2; 31

3 Peppi and Fidelibus, 2008). Further work is necessary to establish optimal concentrations of CPPU and ABA to increase berry size and obtain good berry color, but these preliminary findings suggest that ABA can at least partially overcome the suppressive effects of CPPU on berry color. The physiological activity of ABA sprays was confirmed by measuring mrna levels of the key anthocyanin gene UFGT from the skins of Crimson Seedless grapes treated with solutions containing 0, 150 or 300 mg/l ABA applied at veraison. The level of UFGT mrna increased markedly within one day after application but effects were short-lived, diminishing within three weeks. Rapid changes in UFGT mrna levels were reflected in concurrent color changes in ABA treated fruit, particularly lightness and hue, which decreased after ABA application but were relatively stable after one week post-application in contrast with the lightness and hue of control fruit which decreased gradually throughout the season. Our studies, and those of others (Amiri et al., 2009; Lurie et al., 2009), showed that ABA is an effective alternative to ethephon for improving the color of table grapes. Abscisic acid may also enhance the color of red wines made from treated fruit, so such treatments may be of commercial importance in the future (Anderson et al. 2008; Gu et al., 2011). Together, these studies contributed to the development of ProTone, the first commercial plant growth regulator containing abscisic acid as the active ingredient. Lurie et al. 2009, LITERATURE CITED Amiri, M.E., E. Fallahi and M. Mirjalili Effects of abscisic acid or ethephon at veraison on the maturity and quality of 'Beidaneh Ghermez' grapes. J. Hort. Sci. Biotech. 84: Coombe, B.G. and C.R. Hale The hormone content of ripening grape berries and the effects of growth substances treatments. Plant Physiol. 51: Cantin, C.M., M.W. Fidelibus, and C.H. Crisosto Application of abscisic acid (ABA) at veraison advanced red color development and maintained postharvest quality of 'Crimson Seedless' grapes. Postharv. Biol. Technol. 46: Greyling, M Guidelines for preparing export table grapes. Capespan Exports (Pty) Limited, Bellville, South Africa. 77 p. Gu, S., S. Jacobs and G. Du Efficacy, rate and timing of applications of abscisic acid to enhance fruit anthocyanin contents in 'Cabernet Sauvignon' grapes. J. Hort. Sci. Biotech. 86: Jeong, S.T., N. Goto-Yamamoto, S. Kobayashi, and M. Esaka Effects of plant hormones and shading on the accumulation of anthocyanins and the expression of anthocyanin biosynthetic genes in berry skins. Plant Sci. 167: Kataoka, I., A. Sugiura, N. Utsunomiya, and T. Tomana Effect of abscisic acid and defoliation on anthocyanin accumulation in Kyoho grapes (Vitis vinifera L. x V. labruscana Bailey). Vitis 21: Lee, J.C., and T. Tomana Phsyiological study on anthocyanin development in grapes. II. Effect of sucrose, abscisic acid, and inoleacetic acid on the anthocyanin development of Kyoho grape (Vitis labruscana). J. Kor. Soc. Hort. Sci. 21: Lee, K.S., J.C. Lee, Y.S. Hwang, and I.B. Hur Effects of natural type (S)-(+)-abscisic acid on anthocyanin accumulation and maturity in Kyoho grapes. J. Kor. Soc. Hort. Sci. 38:717:

4 Lurie, S., R. Ovadia, A. Nissim-Levi, M. Oren-Shamir, T. Kaplunov, Y. Zutahy, H. Weksler, and A. Lichter Abscisic acid improves colour development in Crimson Seedless grapes in the vineyard and on detached berries. J. Hort. Sci. Biotech. 84: Pirie, A., and M.G. Mullins Changes in anthocyanin and phenolics content of grapevine leaf and fruit tissues treated with sucrose, nitrate, and abscisic acid. Plant Physiol. 58: Peppi, M.C., and M.W. Fidelibus Effects of Forchlorfenuron and abscisic acid on the quality of 'Flame Seedless' grapes. HortScience 43: Peppi, M.C., M.A. Walker, and M.W. Fidelibus Application of abscisic acid rapidly upregulated UFGT gene expression and improved color of grape berries. Vitis 47:11-14 Peppi, M.C., M.W. Fidelibus, and N. Dokoozlian Abscisic acid application timing and concentration affect firmness, pigmentation, and color of 'Flame Seedless' grapes. HortSci. 41: Peppi, M.C., M.W. Fidelibus, and N.K. Dokoozlian, Application timing and concentration of abscisic acid affect the quality of 'Redglobe' grapes. J. Hort. Sci. Biotech. 82: Peppi, M.C., M.W. Fidelibus, and N.K. Dokoozlian Timing and Concentration of Abscisic Acid Applications Affect the Quality of 'Crimson Seedless' Grapes. Int. J. Fruit Sci. 7: Szyjewicz, E., N. Rosner, and W.M. Kliewer Ethephon ((2-Chloroethyl) Phosphonic Acid, Ethrel, CEPA) in viticulture- a review. Am. J. Enol. Vitic. 35: Szyjewicz, E., N. Rosner, and W.M. Kliewer Ethephon ((2-Chloroethyl) Phosphonic Acid, Ethrel, CEPA) in viticulture- a review. Am. J. Enol. Vitic. 35: Tomana, T., N. Utsunomiya, and I. Kataoka The effect of environmental temperatures on fruit ripening on the tree. II. The effect of temperatures around whole vines and clusters on the coloration of Kyoho grapes. J. Jap. Soc. Hort. Sci. 48:

5 Figure 1. Crimson Seedless table grapes nine weeks after being treated at veraison (berry softening) with solutions containing 0, 150, or 300 mg/l ABA, from left to right, respectively. 34

6 Figure 2. Effect of CPPU and ABA on the color of Flame Seedless grapes; non-treated grapes, grapes treated with 8 g/acre CPPU and no ABA, and grapes treated with 8 g/acre CPPU and 600 mg/l ABA. 35