Browsing by Person "Hoffmann, Petra"

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Lockerbeerigkeit bei Klonen von Spätburgunder (Pinot noir) : Analyse von molekularen Markern und der Einfluss von Gibberellin auf die Traubenmorphologie
(2014) Hoffmann, Petra; Blaich, Rolf
In viticulture, the architecture of the grape cluster affects the quality of the grapes. Compact grape clusters are more prone to B. cinerea infection, which reduces yield (Vail et al. 1998, Vail et al. 1991). Loose clusters have longer pedicel and rachis structures (Alleweldt 1959) and are less susceptible to B. cinerea. For this reason, the cultivation of clones with the loose cluster trait is of great interest. Loose clusters can result from the application of phytohormones, the spacing of the flower clusters, the thinning of fruit, or a reduced pruning. These treatments reduce berry set and promote pedicle elongation when applied to clones with compact clusters (Alleweldt 1959). Genetically based loose clustered grape phenotypes occur among grapevine cultivars. In this study we are able to differentitate between losse and compact clones using the marker FlExp2 on the basis of sequence data. The loose cluster clones show a 4 bp deletion at 219-222 bp and a C/T transition at 231 bp, unlike the compact cluster clones. In all tested Pinot ssp. clones, the sequence correlated to the phenotype. The marker was tested on other varieties such as Riesling, Gewurztraminer, Chardonnay, Chenin blanc, Cardinal and White Chasselas. The phenotypes were again consistent with the sequence. In the case of loose clustered table grapes, a deletion occurs instead of the transition at 231 bp. Additionally, the variety White Gutedel demonst- rated a C/T transition at 217 bp. These results were confirmed by sequencing 30 clo- nes (loose and compact clusters) in two repetitions in both directions. Both markers shwoed two fragments with a four bp difference. The amplification products are a In- del/SNP mutation for loose cluster and a „CTTT“ mutation for copmact cluster grapes.The CAPS and the SCAR marker identified that the trait of bunch architecture is heterozygous. The sequence of the amplification products was distinct for loose and compact cluster types. The SCAR marker shows two amplification products at 162 bp and 166 bp and the CAPS marker at 283 bp and 287 bp. The heterozygosity didn ́t produce a molecular marker for the MAS. In silico, analysis shows that the identified locus is in the Exon in the Vlexp1 gene. This gene is an expansin gene which is responsible for cell elongation (McQueen- Mason 1992). A part of the role which the hormones play in grape Morphology was analyzed in this study. The inflorescences of the genetically loose clustered clone 1-84 Gm did not show increased gibberellin concentration, indicating that gibberellin does not have a influence on the genetic based loose clone (1-84 Gm). However, the auxin concentra- tion in inflorescences of loose cluster clones increases earlier and remains high lon- ger than in those of the compact cluster clone 18 Gm. After a treatment with gib- berellin, the clone 1-84 Gm exhibited increased concentration of both gibberellin and auxin and formed even looser clusters. Similarly, the same treatment applied to the compact clone 18 Gm resulted in looser clusters and increased concentration of gib- berellin and auxin with a higher concentration of auxin for a longer period of time. It remains unclear precisely how the gibberellin treatment induces looser clusters. It may be that there is an interaction between gibberellin and auxin or that the auxin alone causes the cell extension. It remains an open question whether expansin toge- ther with gibberellin or auxin is responsible for the development of loose clusters, or if it is caused by a gibberellin auxin interaction. The growth pattern of the stalks and inflorescences were identified in order to put these results in context with the results of the hormone and genetic analysis. The stalks and inflorescences of the treated and untreated clones were measured weekly before GA3-application and continued four weeks after application. The growth of the flower clusters ended three weeks af- ter anthesis while the stalks grew continuously. In the loose cluster clone 1-84 Gm, the growth of stalks and flower clusters was significantly larger than in the compact cluster clone 18 Gm. The growth behavior of the peclone 18 Gm when treated with gibberellin was identical to the clone 1-84 Gm without gibberellin treatment. Gib- berellin treatment caused a significant increase in the growth of the stalk and flower clusters. The treated loose cluster clones formed the largest stalks while the untrea- ted compact cluster clone 18 Gm the smallest. Such clone growth behavior results in loose cluster architecture.