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Rachel P. Naegele

Botrytis cinerea is a generalist nectrophic fungus capable of infecting more than 200 species of plants ( Droby and Lichter, 2007 ). In Vitis spp., B. cinerea can incite bunch rot, also known as gray mold, in addition to cane and leaf spot

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Imed Dami, Said Ennahli and David Scurlock

typically have a propensity to overcrop, resulting in reduced growth and fruit and wine quality. ‘Vidal blanc’ ( Vitis spp.), a French–American hybrid, also belongs to the group of overcropping hybrids ( Howell et al., 1987 ). The propensity to overcrop has

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Omar Franco-Mora, Edgar Jesús Morales-Rosales, Andrés González-Huerta and Juan Guillermo Cruz-Castillo

( Vitis spp.)” ( IPGRI, UPOV, and OIV, 1997 ) and included 32 vegetative characters related to young (YS), mature (MS), and woody shoot (WS) and young (YL) and mature leaf (ML) ( Tables 4 – 8 ). After vegetative determinations, data were first correlated

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Mageed Abass and C.B. Rajashekar

Heat tolerance and endogenous ABA levels in leaves and cultured grape cells (Vitis spp., cultivars Venus and Veeblanc) were evaluated during beat acclimation. Plants and cultured cells were acclimated at 38 and 36C, respectively. Heat tolerance increased rapidly after exposing plants or cells to acclimation temperatures, reaching a maximum after 10 to 16 hours and 10 to 12 hours for leaves and cultured cells, respectively. Free and bound ABA levels increased sharply during the first hour of heat acclimation, before leaves and cultured cells reached their maximum beat tolerance. The increase in ABA during heat acclimation was 2- to 3-fold that of the nonacclimated control, and the time of the ABA accumulation peak in tissue roughly corresponded to the maximum heat tolerance in leaves and cultured cells. Heat tolerance was induced in cultured cells by exogenous ABA application. Heat tolerance increased significantly after 24 hours of ABA application at 7.6 or 9.5 μm. The results suggest that ABA may be a factor in high-temperature acclimation and beat-tolerance induction in grapes. Chemical name used: abscisic acid (ABA).

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K.A. Roubelakis-Angelakis and S.B. Zivanovitc

A modified culture medium is presented that promotes in vitro rooting of grapevine rootstock and Vitis vinifera L. cultivars even in the absence of plant growth regulators. Study of 15 Vitis genotypes indicated a strong genotype-dependent response to culture medium and growth regulators with respect to formation of roots in onenode shoot segments.

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David M. Hunter and John T.A. Proctor

A system was developed to evaluate the response of grapes (Vitis spp. `Seyval') to soil-applied paclobutrazol. The youngest fully expanded leaf, and its axillary bud, on single shoots 6 to 9 nodes long developing on rooted softwood cuttings, were retained for use in a bioassay. The shoot that developed from the axillary bud exhibited a dosage-dependent growth inhibition following soil applications of paclobutrazol at 4 dosages between 1 and 1000 μg·g-1 soil. Other aerial components showed no response to paclobutrazol. This test plant system has potential for use in physiological studies with soil-applied plant growth regulators. Chemical name used: β -[(4-chlorophenyl)methyl]- α -(1,1-dimethylethyl)1H-1,2,4-triazole-1-ethanol (paclobutrazol).

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D.J. Gray, J.A. Mortensen, CM. Benton, R.E. Durham and G.A. Moore

Ovules of seedless bunch grapes (Vitis spp.) fertilized by controlled pollination increased in size during berry development. More ovules cultured 10 days or 60 to 70 days after pollination became brown compared to those cultured at 20 to 40 days. Cultured ovules developed with and without endosperm. Globular to torpedo stage embryos were recovered. More embryos and plants were recovered from ovules cultured at 40 or 60 days than at 10 or 20 days after pollination. Pollen parent significantly affected both embryo and plant recovery at certain sampling times. BA incorporated into medium significantly increased embryo germination percentage. Electrophoretic analysis of glucosephosphate isomerase in progeny showed that 67% to 88% were hybrids of controlled crosses. Of four vines that fruited thus far, two were seedless. Seedless progeny had smaller seed traces than either parent. Chemical name used: N-(phenylmethyl) -1H-purin-6-amine (BA).

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Bruce P. Bordelon and J.N. Moore

Plant growth regulators (PGRs) [antigibberellins (mepiquat chloride, uniconazole, ancymidol, daminozide, chlormequat, ethephon, methazole), cytokinins (BAP, kinetin, BTP, 2iP), and ABA] were evaluated at various concentrations and timings for promotion of seed trace development and germination of four stenospermic grape cultivars (Vitis spp.): `Venus', `Mars', `Reliance', and `Saturn'. Data include seed trace number per berry, percent of seed traces with endosperm (sinkers), sinker fresh weight, and percent seed trace germination. Several PGRs effectively increased seed number and percent sinkers over control treatments. PGRs had little effect on seed fresh weight and percent germination. PGRs promoted greater increases in percent sinkers than seed number on all cultivars. The number of viable seeds per sample (seed number × percent sinkers) was increased over controls by up to 802% on `Reliance', 239% on `Saturn', 154% on `Mars', and 153% on `Venus'. A moderate percentage of viable seeds from treatments and controls of `Mars', `Venus', and `Saturn' germinated and established normal seedlings. The very small seed traces of `Reliance' did not germinate from either controls or treatments. The results indicate that PGRs can stimulate seed trace formation in some stenospermic cultivars and therefore may be useful tools in grape breeding programs. Chemical names used: abscisic acid (+/-)cis-trans isomer (ABA); a-cyclopropyl-a-(4-methoxy-phenyl)-5-pyrimidinemethanol (ancymidol); 6-benzylaminopurine (BAP); 6-benzylamino-9-(2 tetra-hydropropanyl)-9H-purine (BTP); (2-chloroethyl) trimethyl-ammonium chloride (chlormequat); succinic acid 2,2 dimethyl-hydrazide (daminozide); (2-chloroethyl) phosphonic acid (ethephon); 6-(dimethyl-allylamino) purine (2iP); 6-furfurylaminopurine (kinetin); N,N-dimethyl-piperidinium chloride (mepiquat chloride); [2-(3,4-dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione] (methazole); E-1-(4-chlorophenyl)-4,4-di-methyl-2-(1,2,4-triazol-1-yl)-1-pentan-3-ol (uniconazole).

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Hong Lin and M. Andrew Walker

The DNA extracted from cambium tissues of grape (Vitis spp., Muscadinia rotundifolia Small) rootstocks was found to be suitable for molecular analysis. Its quality was equivalent to that of DNA extracted from leaf tissues, although the yield was higher from leaves. The use of cambium tissue allows DNA extractions during dormancy or from grafted rootstocks where leaves are not available. The DNA extracted was suitable for restriction enzyme digestion and for analysis by restriction fragment length polymorphism (RFLP), randomly amplified polymorphic DNA (RAPD), and simple sequence repeats.

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David M. Hunter and John T.A. Proctor

Paclobutrazol applied as a soil drench at 0, 1, 10, 100, or 1000 μg a.i./g soil reduced vegetative growth of `Seyval blanc' grapevines (Vitis spp.). At all rates, there was a reduction in internode length, while at rates higher than 10 μg a.i/g soil, there was also a reduction in node count. Leaf area produced following treatment declined in response to increasing rates, but specific leaf weight increased. Treatment with paclobutrazol delayed senescence and increased the retention of basal leaves that were nearly fully expanded at the time of treatment. Paclobutrazol application had no effect on fruit set or berry size, but the reduction in vegetative growth following treatment decreased the ability of the vine to supply sufficient photoassimilates for fruit maturation. Chemical name used: ß[(4-chlorophenyl)-methyl]-a-(1,1-dimethylethyl)1H-1,2,4-triazole-1-ethanol (paclobutrazol).