Evolution of Leaf Chlorophylls, Carotenoids and Phenolic Compounds during Vegetation of Some Croatian Indigenous Red and White Grape Cultivars.

During the ripening process of grapes, the grapevine leaves are the most active green organs that are important for photosynthesis, which is closely linked to the development and metabolism of the plant. The detection of plant pigments and phenolic compounds in grapevine leaves can be a good indicator of the ageing process, vine vigor and the plant's ability to respond to fungal attack. In a one-year study, the development of leaf chlorophylls, carotenoids and phenolic compounds during the ripening of six indigenous Croatian grape cultivars and the international cultivars Merlot and Chardonnay was investigated. The chlorophyll a/b ratio and total chlorophyll and total carotenoid concentrations were also investigated. PCA was used to highlight relevant information from the data with the aim of distinguishing individual compounds based on the cultivar and phenological stage. The leaf total hydroxycinnamic acid and flavan-3-ol concentrations decreased slowly during grape development, with the highest concentration immediately after flowering and the lowest during grape ripening. The concentrations of ß-carotene, lutein and xanthophylls tended to decrease during bunch closure or veraison, while the concentration of chlorophylls a and b peaked during veraison and then decreased during grape ripening. This research will provide an opportunity to select cultivars with the physiological adaptation to synthesize secondary metabolites that are important for managing stress conditions.

Biochemical Response and Gene Expression to Water Deficit of Croatian Grapevine Cultivars (Vitis vinifera L.) and a Specimen of Vitis sylvestris.

The biochemical response and gene expression in different grapevine cultivars to water deficit are still not well understood. In this study, we investigated the performance of four traditional Croatian Vitis vinifera L. cultivars ('Plavac mali crni', 'Istrian Malvasia', 'Grasevina', and 'Tribidrag'), and one wild (Vitis vinifera subsp. sylvestris) genotype exposed to water deficit (WD) for nine days under semi-controlled conditions in the greenhouse. Sampling for biochemical and gene expression analyses was performed at days six and nine from the beginning of WD treatment. The WD affected the accumulation of metabolites with a significant increase in abscisic acid (ABA), salicylic acid (SA), and proline in the leaves of the stressed genotypes when the WD continued for nine days. Lipid peroxidation (MDA) was not significantly different from that of the control plants after six days of WD, whereas it was significantly lower (297.40 nmol/g dw) in the stressed plants after nine days. The cultivar 'Istrian Malvasia' responded rapidly to the WD and showed the highest and earliest increase in ABA levels (1.16 ng mg-1 dw, i.e., 3.4-fold increase compared to control). 'Grasevina' differed significantly from the other genotypes in SA content at both time points analyzed (six and nine days, 47.26 and 49.63 ng mg-1 dw, respectively). Proline level increased significantly under WD (up to 5-fold at day nine), and proline variation was not genotype driven. The expression of aquaporin genes (TIP2;1 and PIP2;1) was down-regulated in all genotypes, coinciding with the accumulation of ABA. The gene NCED1 (9-cis-epoxycarotenoid dioxygenase) related to ABA was up-regulated in all genotypes under stress conditions and served as a reliable marker of drought stress. This work suggests that the stress response in metabolite synthesis and accumulation is complex, treatment- and genotype-dependent.

Differences in the levels of pesticides, metals, sulphites and ochratoxin A between organically and conventionally produced wines.

Organic products are generally recognized to be healthier and safer than conventional products. However, the actual scientific data regarding the importance of organic production on particular contaminant/additive content of wines is scarce. This study aimed to evaluate contents of pesticides, metals, sulphites and ochratoxin A in organically (org) and conventionally (conv) produced wines from eleven locations in different winegrowing regions of Croatia. All wines contained significantly lower levels of residues as compared to the maximum limits (MLs) with the exception of excessive amounts of Cu and Zn in one sample. Pb and Mg were mainly significantly less represented in org wines. There were no significant differences in the content of sulphite or ochratoxin A between org and conv wines. Significantly lower total pesticide concentrations and average number of pesticides per sample were obtained in org wines. The majority of ochratoxin A positive wines were from conv wine producers.