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In grapevine, the defense regulator ENHANCED DISEASE SUSCEPTIBILITY (EDS) is present as a multimember gene family and plays a role in basal defense in plants. EDS1 is highly conserved and functional in both, Vitis vinifera cv. 'Cabernet Sauvignon' and Vitis aestivalis cv. 'Norton'; hence, the regulation of EDS1 - regarding tissue specificity and transcript level - may be a key for powdery mildew (PM) resistance in cv. 'Norton', while cv. 'Cabernet Sauvignon' is susceptible. Besides PM resistance, also salicylic acid (SA) signaling and the degree of accumulation in leaves is thought to be associated with EDS1 expression. By preliminary analysis the SA content was determined in leaves of several resistant and susceptible accessions from both species, V. vinifera and V. aestivalis, which corroborates a tendency that SA accumulation and PM resistance may be linked. Further, the putative promoter sequences of the EDS1 genes (pEDS1) from cv. 'Cabernet Sauvignon' and cv. 'Norton' were bioinformatically analyzed with the Genomatix software suite to predict transcription factor binding sites (TFBS) and higher order regulatory models. The analysis revealed that the promoter sequences contain some conserved but also highly variable regions as well as a different set of TFBS and regulatory models. In pEDS1 from cv. 'Cabernet Sauvignon' higher order models containing AHBP, DOFF, L1BX, MYBL, OPAQ and WRKY motifs are predicted. In contrast, in pEDS1 from cv. 'Norton' other putative models are present containing OPAQ and DOFF motifs only. The variations within the regulatory regions of pEDS1 are presumably responsible for specific EDS1 expression and associated SA signaling. [ABSTRACT FROM AUTHOR]

Dormancy in temperate fruit trees is a mechanism of temporary growth suspension, which is vital for tree survival during winter. Studies on this phenomenon frequently employ scientific methods that aim to detect the timing of dormancy release. Dormancy release occurs when trees have been exposed to sufficient chill, allowing them to resume growth under conducive conditions. This study investigates dormancy dynamics in two apple (Malus × domestica Borkh.) cultivars, 'Nicoter' and 'Topaz', by sampling branches in an orchard over 14 weeks (2019 to 2020) and over 31 weeks (2021 to 2022) and subjecting them to a 42-day budbreak forcing period in a growth chamber. Temporal changes in budbreak percentages demonstrated dormancy progression in the studied apple cultivars and allowed the three main dormancy phases to be distinguished: paradormancy (summer dormancy), endodormancy (deep dormancy) and ecodormancy (spring dormancy), along with transition periods between them. Using these data, we explored the suitability of several alternative methods to determine endodormancy release. Tabuenca's test, which predicts dormancy release based on the differences in dry weights of buds with and without forcing, showed promise for this purpose. However, our data indicated a need for considerable adjustments and validation of this test. Bud weight and water content of buds in the orchard did not align with budbreak percentages under forcing conditions, rendering them unsuitable for determining endodormancy release in 'Nicoter' and 'Topaz'. Shoot growth cessation did not seem to be connected with either dormancy progression or dormancy depth of the studied cultivars, whereas leaf fall coincided with the beginning of the transition from endo- to ecodormancy. This work addresses methodological limitations in dormancy research and suggests considering the mean time to budbreak and budbreak synchrony as additional criteria to assess tree dormancy status., (© The Author(s) 2024. Published by Oxford University Press.)