3.3 Leaves
A selection of leaves harvested from the 15 selected vines is given in figure 1G. Morphological and physiological features were strongly affected by phenological phases, fungal presence, symptoms development and their interactions (Table 3).
Fresh and dry weight, moisture content and surfaces of leaves collected during the four phenological phases are presented in figure 2.
During the collections, Lfw (Fig 2A) increase from HV and BWSWRV symptomless leaves. Symptomatic leaves showed always the lowest Lfw.
The highest Ldw (Fig 2B) was recorded from symptomatic leaves collected from BWSWRV at BR phenological phase.
No significant differences were verified on the moisture content of the leaves that range from 89.53 to 94.56% of Lfw.
No differences were shown on leaf surfaces (Fig. 2C) at SL phenological phases, while leaves of HV were significantly smaller than those of diseased plants during the other phenological phases.
Chlorophyll, H2O2 and MDA concentrations in leaves collected during the four phenological phases are given in figure 3. During the SL and FS phases, no significant differences were recorded on chlorophyll content (Fig. 3A) among diseased and HV. At CC and BR phenological phases, diseased plants reduce the chlorophyll concentrations. Symptomatic leaves collected from BWSV and BWSWRV showed the lowest chlorophyll content.
During the four phenological phases, HV vines showed the lowest H2O2 concentrations (Fig. 3B).
Diseased plants increased MDA level (Fig. 3C) in leaves. At CC and BR phases, diseased plants presented a sharp rise in lipid peroxidation level. A further increment in MDA levels also occurred in symptomatic leaves (Fig. 3C).
The ranges of AsA, DHA, GSH and GSSG on leaves collected during the four phenological phases are reported in figure 4.
During the four phenological phases (Fig. 4A), AsA level in leaves collected from HV was similar and was always higher to those found in leaves from diseased vines.
The DHA concentrations were related to vine phenology and fungal presence (Fig. 4B, Tab. 3). At SL and FS phases, leaves collected from BWSWRV showed the highest concentrations of DHA. During CC and BR, symptomless leaves from diseased vines reached the highest DHA levels (Fig. 4B). The content of GSH on leaves collected from HV was higher than diseased plants (Fig. 4C). The GSSG levels on leaves collected from BWSV were lower than HV (Fig. 4D). The GSSG levels on leaves collected from BWSWRV showed the highest concentration at SL, then decrease and reached the lowest-level at BR.
A-RS and G-RS (Tab. 4) decrease in the leaves collected from diseased vines. The lowest redox states were recorded in all symptomatic leaves.
The activities of enzymes involved in ascorbate regeneration are shown in Figure 5. No significant changes were noted in APX activity (Fig. 5A) during the four phenological phases and between healthy and diseased vines. DHA-R activity increase in symptomatic leaves collected from BWSWRV at CC and BR phases (Fig. 5B). AFR-R (Fig. 5C) and G-R (Fig. 5D) activities were lower in leaves collected from diseased vines.