S11 - Session O4 - Understanding and manipulating cold tolerance - Dissecting peach cold hardiness eco-physiology and metabolism

Authors: Ioannis Minas *, David Sterle, Brendon Anthony, Adam Heuberger, Jessica Prenni

Reduction in fruit production due to cold damage in floral tissues is the major limitation to profitability and ultimately survival of temperate fruit industries of North America, including Colorado. Understanding cold hardiness responses to abiotic conditions is key to improve stone fruit performance and productivity in a changing environment. The critical temperatures of the floral buds for two peach cultivars 'Sierra Rich' and 'Cresthaven' were developed in high resolution during the different phases of dormancy (acclimation, maximum hardiness, deacclimation) with differential thermal analysis (DTA). 'Sierra Rich' was the least hardy and exhibited minimum response to freezing events and deacclimated faster as a response to unseasonal warm temperatures, compared to 'Cresthaven' that was acclimated rapidly in response to freezing evens and slowly deacclimated in spring. Biochemical analysis of soluble sugars and starch in floral bud tissue demonstrated that the cold hardy peach cultivar 'Cresthaven' is accumulating higher levels of starch early in the dormancy, which might be responsible for the increased soluble sugar levels towards deacclimation compared to the cold-tender cultivar 'Sierra Rich'. Large scale and non-targeted metabolite profiling (GC-MS) was performed on peach buds from 'Cresthaven' and 'Sierra Rich' at five time points across the three phases of dormancy. Principal component analysis (PCA) of the 232 detected peach bud metabolites indicated distinct metabolite profiles at each of the three distinct dormancy phases. Further, the two cultivars differed at each time point, indicating a genotype x date source of variation in the metabolome which highlights that metabolite shifts during dormancy, and that the dynamics of the response are variable between cultivars with different frost tolerance. This further demonstrates that the active cross talk between the environment and the dormant reproductive organs is regulating metabolic pathways that might contribute to tree adoptability to environmental changes.