Biology subjects

Cadle-Davidson, L.

Publications and source records attributed to Cadle-Davidson, L..

2 recordsLinked to original sources

bioRxiv2020

Stable QTL for malate levels in ripe fruit and their transferability across Vitis species

Malate is a major contributor to the sourness of grape berries (Vitis spp.) and their products, such as wine. Excessive malate at maturity, commonly observed in wild Vitis grapes, is detrimental to grape and wine quality and complicates the introgression of valuable disease resistance and cold hardy genes through breeding. This study investigated an interspecific Vitis family that exhibited strong and stable variation in malate at ripeness for five years and tested the separate contribution of accumulation, degradation, and dilution to malate concentration in ripe fruit in the last year of study. Genotyping was performed using transferable rhAmpSeq haplotype markers, based on the Vitis collinear core genome. Three significant QTL for ripe fruit malate on chromosomes 1, 7, and 17, accounted for over two-fold and 6.9 g/L differences in ripe fruit malate, and explained 40.6% of the phenotypic variation. QTL on chromosomes 7 and 17 were stable in all and in three out of five years, respectively. Variation in pre-veraison malate was the major contributor to variation in ripe fruit malate (39%) and their associated QTL overlapped on chromosome 7, indicating a common genetic basis. However, use of transferable markers on a closely related Vitis family did not yield a common QTL across families. This suggests that diverse physiological mechanisms regulate the levels of this key metabolite in the Vitis genus, a conclusion supported by a review of over a dozen publications from the past decade, showing malate-associated genetic loci on all 19 chromosomes.

genetics↗

bioRxiv2019

Epiphytic Microbiome of Grapes Berries Varies Between Phenological Timepoints, Growing Seasons and Regions

Extensive research into the microbial ecology of grapes near harvest, with a primary focus on yeasts, has improved our understanding of some components of variation that influence grapevine terroir. Metagenomic tools enable a broader exploration of the plant microbiome and components of variability due to such factors as year, location, management, and phenological stage. In 2014, to characterize the microbial changes of the grape surface over the course of the growing season in the Finger Lakes region of New York, we examined the epiphytic microbiome of grapes at five key phenological stages: pea-sized, bunch closure, Veraison, 15 Brix and harvest. This experiment was repeated in two subsequent years in the Finger Lakes, New York in 2015, and in Tasmania, Australia in 2016, to examine variability of regional terroir. We found significant shifts in taxa presence and relative taxa abundance between phenological timepoints, and determined that the epiphytic microbiome differed significantly not just between regions but also within a single region from one year to the next. These findings call into question the role of the phytobiome in the expression of terroir, as the phytobiome is dynamically responding to its environment, within and between years and locations. On the berry surface in particular, these dynamics are complicated by weather and management. Understanding that the grape surface microbiome is consistently changing may influence how we manage the berry epiphytic microbiome, potentially affecting disease management and vinification decisions.

microbiology↗