Vitis36 (2), 77-83 (1997)

Elicitation and accumulation of stilbene phytoalexins in grapevine berries infected by Botrytis cinerea*)

by

I) Istituto di Frutti-Viticoltura, Universita Cattolica S. Cuore, Piacenza, Italia 2l Istituto di Entomologia e Patologia vegetale, Sezione Patologia vegetale, Universita Cattolica S. Cuore, Piacenza, Italia 3l Istituto di Chimica Agraria ed Ambientale, Universita Cattolica S. Cuore, Piacenza, ltalia

S um m a r y : At three developmental stages berries of field-grown Castor (interspecific crossing) and Huxelrebe (V, vinifera L. crossing) werein vitro inoculated with two strains of Botrytis cinerea Pers. to investigate the response ofberries to fungal infection with respect to the time course of phytoalexin (trans-resveratrol, E-viniferin and pterostilbene) accumulation and visual disease symptoms. In infected berries the amounts of E-viniferin dominated over pterostilbene. The stilbene phytoalexin content decreased during berry development and sugar accumulation. Grape varieties reacted differently toB. cinerea strains with regard to stilbene response and visual symptoms. Mechanical darnage of the berry skin induced uninfected berries to synthesize low amounts of phytoalexins. It can be assumed that after extraction and degradation E-viniferin of mature berries is a source of resveratrol in wine.

K e y w o r d s : grapevine, berry, trans-resveratrol, E-viniferin, pterostilbene, Botrytis cinerea.

Introduction Materials and methods

Botrytis cinerea Pers., anamorph of Botryotinia P 1 an t m a t e r i a 1 : 15-year-old plants of Castor fuckeliana (De Bary) Whetzel, the causal agent of grey (Oberlin 595 F1 x Foster's White Seedling) and the mould, seriously reduces grape yield and quality by con­ V. vinifera L. variety Huxelrebe (Weißer Gutedel x verting sugar into glycerol and gluconic acid and by pro­ Courtillier musque), grown in an experimental vineyard ducing eniymes catalysing oxidation of phenolic com­ near Piacenza (northern Italy), were used for the trial. Cas­ pounds such as stilbene phytoalexins. Rapid accumulation tor was originally supplied by the Institut für Reben­ of phytoalexin (trans-resveratrol and €-viniferin) has been züchtung Geilweilerhof, Siebeldingen/Germany, while associated with the resistance of grapevines to B. cinerea Huxelrebe was obtained from the LA für Rebenzüchtung (LANGCAKE and Mc CARTHY 1979; BLAICH et al. 1982; Alzey, Germany. Castor is considered to be resistant to JEANDET and BESSIS 1989), which is normally observed in B. cinerea under German conditions (ALLEWELDT 1980), American species and interspecific crossings. Phytoalexins whilst Huxelrebe is susceptible (HILLEBRAND et al. 1984). represent only one mechanism involved in resistance These two varieties were chosen due to their different dis­ (FREGONI 1983; FARETRA and MAYER 1992), others are thick­ ease resistance and due to their phenological similarity in ness and structure of cuticular waxes (ROSENQUIST and the Piacenza area (BAVAREsco and BosELLI 1986). Grape MORRISON 1989; CoMMENIL et al. 1996), low number of cu­ berries from 20 clusters (chosen at random from 5 plants ticle perforations (BEssrs 1972 a; BLAICH et a/.1984 ), of each variety) were sampled about 25 d after fruit set, at polypbenals and glycolic acid (JEANDET and BEssis 1989; veraison and during ripening, i.e. in the first, second and PEZET and PoNT 1988 a), and probably PR proteins (RENAULT et al. 1996). On the other band, phytoalexin synthesis of Table 1 susceptible plants is reduced, and does not reach high con­ Average berry weight, soluble solids and pH of berry juice of centrations due to both, the genetic pattern traits of the Castor and Huxelrebe during berry development vines and the activity of fungallaccase-like enzymes (PEZET et al. 1991; JEANDET et al. 1993). The subject of stilbene Average Soluble pH phytoalexins and disease resistance has been recently re­ berry solids 0 weight (g) ( Brix) viewed by DERCKS et al. (1995). Trans- and cis-isomers of resveratrol are also present 25 d after fruit set 1.1 4.1 2.72 in wine (SIEMANN and CREASY 1992), and resveratrol is sup­ Castor at veraison 1.4 7.5 2.42 posed tobe the active principle of red wines reducing heart during ripening 2.7 19.4 3.39 deseases (SEIGNEUR et al. 1990; RENAUD and DE LoRGERIL 1992). 25 d after fruit set 1.0 4.0 2.66 The aim of this paper was to study the role of stilbene Huxelrebe at veraison 2.1 10.8 2.55 phytoalexins in the B. cinr;rea grapevine interaction, and during ripening 2.9 18.0 3.24 their significance for the origin of resveratrol in wine.

Correspondence to: Dr. L. ßAVARESco, Universita Cattolica del Sacro Cuore, Facolta di Agraria, Istituto di Frutti-Viticoltura, Via Emilia Parmense, 84, 1-29100 Piacenza, Italy. Fax: (523) 599268. E-mail:[email protected] *) Research supported by the Ministery of Agriculture, Special Project: "Plant genetic resistance against biotic and abiotic stresses" (1992-1994). 78 L. BAVAREsco, D. PETEGOLLI, E. CANTÖ, M. FREGONI, G. CHIUSA and M. TREYISAN third stage of berry growth. After analysis of berry weight, gular metal net (6 rows of 8 berries each), with square soluble solids and pH (Tab. 1) the berries were artificially links, a small sterile aluminium basin and blotting paper inoculated with B. cinerea. on the bottom. Berry skins were pricked by a sterile nee­ dle close to the pedicel and a drop of inoculum (20 j..Ll) was P r e p a r a t i o n o f f u n g a I i n o c u 1 u m : Two placed upon. Contra! (uninoculated ) berries were treated B. cinerea strains (SAR 2116 and SAR 2228) supplied by with a suspension without conidia. The basins were F. FARETRA (Dept. Plant Protection, University of Bari) were wrapped up with a plastic bag and placed inside a growth obtained from crossings between monoascosporic isolates chamber (25±1 °C, 16 h of light per day, light intensity: collected from grapevine, rose and carnation in the Apu1ia 40 j..lmol m·2 s·1). region (southern Italy). Due to observations of 1eaf and berry symptoms at severa1 grape varieties at veraison and Extraction and identification of maturity, SAR 2116 is considered to be of 1ow and s t i l b e n e p h y t o a I e x ins : 0.5, 1, 2, 4, 8 and 16 d SAR 2228 to be of high virulence. after inoculation berries were analysed. All analytic val­ Fungal colanies were transferred and cultured in Petri ues are means of 3 replicates of 8 berries each. To analyse dishes containing 20 ml of 1.5 % Czapek (Dox) Agar (CZ), the stilbene phytoalexins trans-resveratrol, f-viniferin and according to SMITH and ÜNIONS (1983); they were incu­ pterostilbene berries were ground in a mortar with 30 ml bated at 25± 1°C and a 12 h photoperiod for 2 weeks. of 95 % methanol and vigorously shaken for 20 min. Seeds Conidial suspension was prepared from 14-day-old cul­ ofthe second (veraison) and third (maturity) sampling were tures by flooding the Petri dishes with a sterile solution discarded before maceration in order to avoid extraction (0.01 % Tween 20) and scraping the agar surface to dis­ of constitutive resveratrol. A filtration by GF/A Whatman lodge conidia. The suspension was filtered through a dou­ filters followed, the liquid was evaporated in vacuo at 40 °C ble layer cheese cloth and conidia concentration was meas­ and the water fraction was extracted twice with 5 ml 5 1 ured using a Bürker chamber and set to 5 x 10 conidia-mJ· • ethylacetate and 5 ml NaHC03 (5 %), by phase partition­ ing. The organic phase was evaporated to dryness and B e r r y i n o c u I a t i o n : Berries with pedicels stilbene compounds were recovered by 2 ml plus 2 x, 1 ml were carefully excised from the rachis in order to preserve methanol ( 100 %) and stored in adiactinic glass vials at their integrity and washed in running water for 2 h. After 4 oc. Just before stilbene analysis the samples were evapo­ surface sterilization (2 % NaOCI, 5 min ) and rinsing twice rated by a stream of dry N2 and dissolved in 2 ml of metha­ in sterile water, 48 berries were placed on a sterile rectan- nol 50 %. Stilbene analyses were done by HPLC as de-

Table 2 Effect of grape variety, berry development, fungus strain and incubation time on berry phytoalexin concentration and. infection index

Trans-res veratro I E-Viniferin Pterostilbene Infection ~gg - t FW ~gg·l FW ~gg·t FW index %

1 Grape variety ) Castor 5.00 6.64 0.13 5.3 Huxelrebe 2.11 3.30 0.06 7.1 LSDo.o; 1.07 1.84 n.s. n.s.

Stage of berry 25 d after fruit set 6.56 10.30 0.24 3.5 developmenf) at veraison 3.80 4.06 0.03 4.7 during ripening 0.30 0.54 0.01 10.4 LSDoos 1.32 2.26 0.10 6.0

2 Fungus strain ) control 1.64 1.37 0.04 0.5 SAR 2116 3.79 5.35 0.03 9.5 SAR 2228 5.24 8.19 0.21 8.7 LSDo.o; 1.32 2.26 0.10 7.1

3 Incubation time ) 0.5 d 0.96 0.49 0.17 0 1 d 2.52 1.79 0.25 0 2d 6.56 4.23 0.01 0 4d 7.31 11.69 0.06 2.7 8d 2.54 7.58 0.05 9.4 16 d 1.44 4.04 0.01 25.2 LSDOOS 1.86 3.19 0.14 4.7

1 3 ' ) Each stilbene value is the mean of 162 (I), I 08 (2) or 54 data (3). Phytoalexins in grapevine berries 79 scribed by PEZET et al. (1994), utilizing, as standard com­ pounds, trans-resveratrol (Sigma), c-viniferin (provided by ( • cont rol •sAA 2116 0SAR ~ - G. Hoos, formerly Institut für Rebenzüchtung Geil­ 25 daher du ring fruit aet at v eraiaon ripening weilerhof, Siebeldingen/Germany), and pterostilbene (pro­ 20 vided by R. PEZET, FARS Changins, Nyon, Switzerland). LSD0 0& I A liquid chromatograph (Hewlett Packard 1090 L, Waldbronn, Germany) with autosampler (1 0 111 of injec­ tion volume) and DAD (diode array detector, A. = 310 nm) and a Lichrospher column (100 RP, Merck, 125 x 4 mm, 5 11m particle size) were used. Elution: gradient of metha­ nol (from 20 to 80 % in 27 min) and formic acid (0.24 %); flow rate: 1.0 ml·min -1.

3 5 25 d after duri ng truit set rlpe n i ng V i s u a I in f e c t i o n s y m p t o m s : Symptoms 3 0 LSD 0. ~ I were classified according to the following scale: 0 =no symp­ ~ 25 u..: toms; 1 = partial berry infection; 2 = total infection with -b> 2 0 (1.1.) aerial mycelium. The infection index was cal­ · ~ 15 culated as: 'E ::::::: 10 \U I. 1.= [(.f n. X i) I (1 n. X 2)] X 100 t=O l t=O l GASTOR HUXIiöt..FI E BE where i = scale rating (0 to 2), n = number of berries in each 25 d alter lruit set scale rating. 0 .8 Statist i c a 1 an a I y s i s : A four-way-ANOVA ( considering genotype, berry growth stage, fungal strain, incubation time as main effects) with interactions was uti­ lized, and the means were compared by using the LSD test (5 % Ievel). Data of berry infection rate were submitted to angular transformation.

Fig. I: Concentration of trans-resveratrol, E-viniferin and ptero­ Results stilbene in benies as a function of grape variety, berry develop­ ment and fungus strain. On the average, berries of the Botrytis-resistant vari­ 1 25 days alter veraison ripening ety Castor synthesized more trans-resveratrol (5!lg g- FW) fruit-set 20 and c-viniferin (6.6 11g g- 1 FW) compared to the suscepti­ ble variety (2.1 and 3.3 11g g -1 FW, respectively). The amount of pterostilbene was much lower than the other LSD, " control ___ stilbenes (no significant difference between the two varie­ 15 •sAR 2116 ties, Tab. 2). The concentrations of the three compounds 0 SAR 2228 decreased from the first to the third stage of berry growth ~---····-·- indicating very Iow Ievels at ripening. Also uninoculated berries produced stilbenes (Tab. 2), even though to a much Iower extent than the inoculated ones; SAR 2228 elicited a higher stilbene synthesis than SAR 2116. The trans-resveratrol and c-viniferin accumulation was enhanced up to the fourth day after inoculation and then dropped till day 16. The values of trans-resveratrol were 0 higher than those of c-viniferin until the second day after Cu.ASTOR~ --HUXELAEBE~----- Cw.r~ASTOR ~-~HUXELREBE~ ----CASTOR~"- -J!HUXELAEBE~ inoculation, while afterwards more c-viniferin than trans­ Fig. 2: Berry infection index as a function of grape variety, berry resveratrol was found. A maximum of 0.25Jlg g- 1 FW of development and fungus strain. pterostilbene was reached 1 d after inoculation (Tab. 2). Castor was less infected than Huxelrebe, and the in­ synthesized the highest Ievels of the three stilbenes, while fection index increased with berry development and with in Huxelrebe the two Botrytis strains elicited the same incubation time; B. cinerea strains induced similar symp­ amount of phytoalexins (Fig. 1). At veraison, on the other toms (Tab. 2). hand, the SAR 2116 strain induced higher Ievels of trans­ During the first stage of berry growth, the effect of the resveratrol and c-viniferin than SAR 2228 in both varie­ SAR 2228 strain on Castor was significant; this variety ties; no significant differences were found at ripening. 80 L. BAVAREsco, D. PETEGOLLI, E. CANTÖ, M. FREGONI, G. CHIUSA and M. TREVISAN

control lnoculation wi1h inoculation wi1h (uninoculated berries) SAR 2116 SAR 2226

80 80 80

Q)~ -(/), "-oo ·-"'--::JOI -=.3..... 0 (J) iä 40 40 ~i ctS .,~ "0 ..'r <::!:) 20 L!)l! C\1""

4 8 10 12 14 1e 2 e 10 12 14 2 4 6 10 12 14 16 incubation time (d) lncubation time (d) lncubation time (d)

control inoculation with inoculation with (uninoculated berries) SAR 2116 SAR 2228

20 20

3i c ~15 15 0 (/) ·- -'3."' ~ e1o 10 (J)l! > ..!: ..... 1ti ~ 5 !!:. ... 0 6 10 12 14 16 0 10 12 1~ 16 2 6 10 12 14 16 incubation time (cl) incubation time (cl) lncubation time (d)

control inoculation with inoculation with (uninoculated berries) SAR 2116 SAR 2228

0>3i C u.: o.e o.e 0.8 ·- t" c 01 (J)-'3, .~ a. 0 0,6 0,6 0.6 ·c -Ii Ii •• 0,4 0> i 0,4 0,4 c ~ ·-.,.... <: ::J 1!! "0 ""0,2 0,2 ... ·~ . . ~0.2....

_j_...... L__J 0 0 0 2 4 6 10 12 14 16 0 0 6 e 10 12 14 16 0 4 10 12 14 16 incubation time (d) incubation time (cl) incubation time (d)

Fig. 3: Time course of trans-resveratrol accumulation in berries of two varieties and the effect of fungus strain. Each value is the mean of three replicates.

During the frrst stage of beny growth no differences of stage of beny development and fungal strain (Figs. 3, 4). infection syrilptoms between the two strains were observed At the early stage of berry development and when infec­ with Castor while with Huxelrebe the SAR 2116 strain in­ tion was done with SAR 2228, Castor showed a more rapid duced more symptoms than SAR 2228 (Fig. 2). At veraison response to elicitation than Huxelrebe. It is interesting to no infection differences between the two strains were re­ note that berries sarnpled at veraison still had a consistent corded, whereas at maturity the effect was different depend­ stilbene content 16 d after inoculation; even at ripening ing on the variety. the phytoalexins were not completely degradated 16 d af­ The time course of trans-resveratrol and E-viniferin ter the treatment. accumulation differed distinctly depending on the variety, Phytoalexins in grapevine berries 81

control inoculation wlth inoculation with (uninoculated berries) SAA 2116 SAA 2228

150 150

100 100

50 50

o.~~~~~~~~ ~~~~~6~~8==1~0~12==1~~~16 8 10 12 1~ 16 0 8 10 12 1~ 16 incubation time (d) incubation time (d) incubation time (d)

control inoculation with inoculation with (uninoculated berries) SAA 2116 SAA 2228

20 20

15

~10"' 10 e ! .5 >. 111 5 ...... 6 10 12 1~ 16 10 12 .. 16 incubation time (d) incubation time (d) inoubation time (d)

control inoculation with inoculation with (uninoculated berries) SAA2116 SAA 2228

3

0> c 2.5 2,5 2.5 c ~ Q)a.o. - 2 1 "i:: ~15 1,5 •• 0) -~' c ! "i:: ~ 1 ::J 'II "'0 0,5

10 12 14 16 incubation time (d) incubation time (d) incubation time (d)

Fig. 4: Time course of E-viniferin accumulation in berries of two varieties and the effect of fungus strain. Each value is the mean of three replicates.

Discussion been obtained for the capability of interspecific varieties and American species to accumulate high stilbene Ievels This paper reports for the first time appreciable in elicited leaves (STEIN and Hoos 1984; STEIN and BLAICH amounts of trans-resveratrol and f.-viniferin in berries of 1985; ßAVARESCO and EISACH 1987; BAVARESCO 1993; two genotypes which had been infected with two B. cinerea BAVAREsco et al. 1994), while only few data are available strains at different developmental stages. As expected, the for elicitation in berries (CREASY and CoFFEE 1988; JEANDET interspecific crossing Castor synthesized more stilbenes et al. 1991 and 1995 b ). The average Ievels of trans­ than the intraspecific crossing Huxelrebe, especially in the resveratrol were always lower than those reported in the early stages of berry development. Evidence has already Iiterature for UV-elicited berries of V. vinifera cv. Pinot 82 L. BAVARESCO , D. PETEGOLLI , E. CANTÖ , M. FREGONI, G. CHIUSA and M. TREVISAN noir and V. labrusca (JEANDET et al. 1991). This is likely strains were observed. This may partly be due to changes of due to berry colour, since there is some evidence that wines virulence of the fungal strains (SBAGHI et al. 1996). from red varieties have twice as high trans-resveratrol con­ The time course of trans-resveratrol and e-viniferin centrations than white ones (JEANDET et al. 1995 a). This is accumulation in berries was similar, with the maximum not always true, because, according to SoLEAS et al. (1995), amounts 4 d after inoculation. The late e-viniferin data some white grape varieties had higher trans-resveratrol skin being higher than those of trans-resveratrol confirm the concentrations than red varieties. role of the latter as precursor of viniferins. On the other Quantitatively e-viniferin seems to be the most im- · hand, pterostilbene showed a more rapid response to portant stilbene of B. cinerea berry interactions. After the elicitation with the highest value 24 h after inoculation. finding of e-viniferin as new phytoalexin by LANGCAKE and Besides synthesizing higher total amounts of stilbenes, PRYCE ( 1977) very few data have been obtained on its con­ Castor showed also a faster accumulation of trans­ centration in berries (LANGCAKE 1981 ). Like trans­ resveratrol and e-viniferin than Huxelrebe. The response resveratrol, the interspecific crossing synthesized more of ripe berries was very fast with regard to trans-resveratrol. e-viniferin than the V. vinifera cultivar. No correlations between the time course of the three Finally, in both varieties the concentration of ptero­ stilbenes and the infection index was found, except 4, 8, stilbene in the berries was much lower than that of the and 16 d after infection, when decreasing stilbene Ievels other stilbenes. This compound is considered to be an im­ were related to increasing rates of infection. portant resistance factor of unripe berries to grey mould (PEZET and PüNT 1988 a). The decrease of stilbene concentration from early Acknowledgements stages of berry development till ripening confirms data in Iiterature (CREASY and CoFFEE 1988; JEANDET etal. 1991). The authors want to thank Dr. G. Hoos, forrnerly Institut für The high stilbene Ievel before veraison is considered to be Rebenzüchtung Geilweilerhof, Siebeldingen/Germany, for sup­ one of the factors explaining the often recorded rate of plying E-viniferin Standard; Dr. R. PEZET, Federal Agricultural grey mould resistance (HILL et al. 1981). According to Research Station Changins, Nyon, Switzerland, for supplying JEANDET et al. (1995 d) the decreasing stilbene concentra­ pterostilbene standard; Prof. F. FARETRA, Department of Plant tion from veraison to maturity could be explained by a Protection, University ofBari, Italy, for supplying Botrytis cinerea competition between chalcone ~ynthase and stilbene strains and for helpful advice. synthase, since the former is involved in the flavonoid syn­ thesis, and the latter in the stilbene biochemical pathway. Low stilbene concentrations in Botrytis-e!icited berries at References ripening, could also be due to a detoxification of phyto­ alexins andlor a laccase-like stilbene oxidase activity, which ALLEWELDT, G.; 1980: The breeding of fungus- and phylloxera-resistant has been investigated by PEZET et al. (1991), JEANDET et al. grapevine varieties. Proc. 3rd Int. Symp. Grape Breed. June 15-18, 242-250 Davis (California). University of California Press. (1993) and SBAGHI et al. (1996) (for further discussion see BAVAREsco, L.; 1993: Effect of potassium fertilizer on induced stilbene also Hoos and BLAICH 1988). synthesis in different grapevine varieties. Bull. O.I.V. 66, 674-689. Even stilbene concentration of uninoculated berries --; BosELLI, M.; 1986: Caratteristiehe produttive e qualitative di aleuni decreased during berry growth, reaching at ripening simi­ nuovi incroci ed ibridi tedeschi coltivati in climi temperati sub­ eontinentali. C.R. 4eme Symp. Intern. Genet. Vigne. l3-18Avril1985, lar values as Botrytis-infected ones. Stilbene production Verone. Vignevini 13 (suppl. 12), 234-239. in control berries can be explained by an elicitation due to - -; EIB ACH, R.; 1987: Investigations on the influence of N fertilizer on needle pricking, or by an accidental infection with fungi resistanee to powdery mildew (Oidium tuckeri) downy mildew other than B. cinerea, since unelicited berries normaliy do (Plasmopara viticola) and on phytoalexin synthesis in different grape­ vine varieties. Vitis 26, 192-200. not produce stilbenes. BESSIS ( 1972 b) has reported the pres­ - -; FREGONI, M.; PETEGOLLI, D.; 1994: Effect of nitrogen and potassium ence of B. cinerea on berries which did not exhibit disease fertilizer on indueed resveratrol synthesis·in two grapevine genotypes. symptoms, thus stilbene synthesis might have been induced Vitis 33, 175-176. (JEANDET et al. 1995 c), even though the berries are appar­ BESS IS , R.; 1972 a: Etude de l'evolution des stomates et des tissus peristomatiques du fruit de la vigrte. C.R. Aead. Sei. Paris 274, ently healthy. According to EcroR et al. (1996) many Vitis 2158-2161. rotundifolia varieties accumulate resveratrol in unelicited --; 1972 b: :Etude en mieroseopie electronique a balayage des rapports berries while ÜKUDA and YOKOTSUKA ( 1996) found very entre l'höte et Je parasite dans Je cas de Ia pourriture grise. C.R. Aead. low Ievels of resveratrol in ripe and apparently healthy Sei. Paris 274,2991-2994. BLAICH, R.; BACHMANN, 0.; STEIN, U. ; 1982: Causes biochimiques de Ia berries of V. vinifera and interspecific varieties growing in resistance de Ia vigne a Botrytis cinerea. Bull. OEPP 12, 167-170. Japan. - -;STEIN, U.; WJND, R.; 1984: Perforationen in der Cuticula von Weinbeeren The e-viniferin concentration of both control and in­ als morphologischer Faktor der Botrytisresistenz. Vitis 23, 242-256. oculated berries at ripening, was higher than trans­ CoMMENIL, P.; BELJNGHERI, L.;AuDRAN, J. C.; CoLLAs,A.; DEHORTER, B.; 1996: Mise en evidence d'une activite anti-Botrytis dans !es cires epi­ resveratrol and pterostilbene; this oligo-stilbene is a possi­ eutieulaires de jeunes baies de Vitis vinifera, variete Pi not noir. 1. In­ ble source of resveratrol in wine (GoLDBERG et al.1995). tern. Sei. Vigne Vin 30, 7-13. The effect of the fungal strain on phytoalexin Ievel CREASY, L. L.; CoFFEE, M.; 1988: Phytoalexin produetion potential of grape was evident in the early stage of berry growth in Castor. berries. J. Amer. Soc. Hort. Sei. 113, 230-234. DERCKS, W.; CREASY, L. L. ; LuczKA-BAYLES, C. J.; 1995: Stilbene During ripening, no significant differences between the phytoalexin and di sease resistance in Vitis. In: DA NIEL, M .; Phytoalexins in grapevine berries 83

PuRKAYASTA, R. P. (Eds.): Handbook of Phytoalexin Metabolism - -; Mc CARTHY, W. V.; 1977: The relationship of resveratrol produc­ and Action, 287-315. Marcel Dekker lnc., New York. tion to infection of grapevine leaves by Botrytis cinerea. Vitis EcroR, B. J. ;MAeEE, J. B.; HEewooo,C. P.; CoieN, M. J.; 1996: Resveratrol 18, 244-253. concentration in Museactine berries, juice, pomace, purees, seeds and - -; PRYCE, R. J.; 1977: A new class of phytoalexins from grapevines. wines. Amer. J. Enol. Viticult. 47, 57-62. Experientia 33, 151-152. FARETRA, F.; MAYER,A. M.; 1992: Genelies of cream mutants of Botryotinia ÜKUDA, T.; YoKOTSUKA, K.; 1996: Trans-resveratrol concentrittion in berry fuckeliana ( Botrytis cinerea) with aberrant production of laccase en­ skins and wines from grapes grown in Japan. Amer. J. Enol. Viticult. zyme. In: VERHOEFF, K. ; MALATHRAKIS, N. E.; Wn.LIAMSON, B. (Eds.): 47, 93-99. RecentAdvances in Botrytis Research, 25-29. 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