Editing VvDXS1 for the creation of muscat flavour in Vitis vinifera cv. Scarlet Royal.

Muscat flavour represents a group of unique aromatic attributes in some grape varieties. Biochemically, grape berries with muscat flavour produce high levels of monoterpenes. Monoterpene biosynthesis is mainly through the DOXP/MEP pathway, and VvDXS1 encodes the first enzyme in this plastidial pathway of terpene biosynthesis in grapevine. A single-point mutation resulting in the substitution of a lysine with an asparagine at position 284 in the VvDXS1 protein has previously been identified as the major cause for producing muscat flavour in grapes. In this study, the same substitution in the VvDXS1 protein was successfully created through prime editing in the table grape Vitis vinifera cv. 'Scarlet Royal'. The targeted point mutation was detected in most of the transgenic vines, with varying editing efficiencies. No unintended mutations were detected in the edited alleles, either by PCR Sanger sequencing or by amplicon sequencing. More than a dozen edited vines were identified with an editing efficiency of more than 50%, indicating that these vines were likely derived from single cells in which one allele was edited. These vines had much higher levels of monoterpenes in their leaves than the control, similar to what was found in leaf samples between field-grown muscat and non-muscat grapes.

Growing season moisture drives interannual variation in woody productivity of a temperate deciduous forest.

The climate sensitivity of forest ecosystem woody productivity (ANPPstem ) influences carbon cycle responses to climate change. For the first time, we combined long-term annual growth and forest census data of a diverse temperate broadleaf deciduous forest, seeking to resolve whether ANPPstem is primarily moisture- or energy-limited and whether climate sensitivity has changed in recent decades characterised by more mesic conditions and elevated CO2 . We analysed tree-ring chronologies across 109 yr of monthly climatic variation (1901-2009) for 14 species representing 97% of ANPPstem in a 25.6 ha plot in northern Virginia, USA. Radial growth of most species and ecosystem-level ANPPstem responded positively to cool, moist growing season conditions, but the same conditions in the previous May-July were associated with reduced growth. In recent decades (1980-2009), responses were more variable and, on average, weaker. Our results indicated that woody productivity is primarily limited by current growing season moisture, as opposed to temperature or sunlight, but additional complexity in climate sensitivity may reflect the use of stored carbohydrate reserves. Overall, while such forests currently display limited moisture sensitivity, their woody productivity is likely to decline under projected hotter and potentially drier growing season conditions.

Role of tree size in moist tropical forest carbon cycling and water deficit responses.

Drought disproportionately affects larger trees in tropical forests, but implications for forest composition and carbon (C) cycling in relation to dry season intensity remain poorly understood. In order to characterize how C cycling is shaped by tree size and drought adaptations and how these patterns relate to spatial and temporal variation in water deficit, we analyze data from three forest dynamics plots spanning a moisture gradient in Panama that have experienced El Niño droughts. At all sites, aboveground C cycle contributions peaked below 50-cm stem diameter, with stems ≥ 50 cm accounting for on average 59% of live aboveground biomass, 45% of woody productivity and 49% of woody mortality. The dominance of drought-avoidance strategies increased interactively with stem diameter and dry season intensity. Although size-related C cycle contributions did not vary systematically across the moisture gradient under nondrought conditions, woody mortality of larger trees was disproportionately elevated under El Niño drought stress. Thus, large (> 50 cm) stems, which strongly mediate but do not necessarily dominate C cycling, have drought adaptations that compensate for their more challenging hydraulic environment, particularly in drier climates. However, these adaptations do not fully buffer the effects of severe drought, and increased large tree mortality dominates ecosystem-level drought responses.

Phenological diversity in wild and hybrid grapes (Vitis) from the USDA-ARS cold-hardy grape collection.

Wild grape relatives and hybrids have been useful in breeding for tolerance to biotic and abiotic stress, however, few studies have emphasized wild and hybrid grapevines for phenological diversity. Utilization of phenological diversity in grapevine breeding could facilitate expansion of grape production into more varied climate regions. Budbreak, bloom, and veraison observations for 1583 accessions from 20 taxa from the United States Department of Agriculture Vitis collection in Geneva, New York, USA. Genotypic and species variation were estimated. Vitis vinifera ancestry was estimated in Vitis hybrids using principal components analysis. Observations ranged 26.6-162.1 (79-141 JD) with an average of 82.6 GDD (118 JD) for budbreak, 206.8-1055.2 (141-222 JD) with an average of 371.9 GDD (163 JD) for bloom, and 849.9-1627.0 (202-290 JD) with an average of 1207.9 GDD (235 JD) for veraison. Seasonal correlations were high for bloom and veraison (0.85-0.95) and moderate for budbreak (0.61-0.65). Moderate heritability was estimated for veraison (0.62) and bloom (0.49), and weak heritability for budbreak (0.2). The species effect was greatest in bloom and explained 42% of the variation, with increasing bloom GDD associated with increasing contribution of V. vinifera in Vitis hybrids.