Ascorbic acid and prunasin, two candidate biomarkers for endodormancy release in almond flower buds identified by a nontargeted metabolomic study

Abstract

Temperate fruit trees belonging to Prunus species have the ability to suspend (induce dormancy) and resume growth periodically in response to environmental and seasonal conditions. Endodormancy release requires the long-term accumulation of chill. Upon accumulation of cultivar-specific chill requirements, plants enter the state of ecodormancy, which means the ability to grow has been restored, depending on the fulfilment of heat requirements. As many different metabolic pathways are implicated in endodormancy release, we have performed a metabolomic analysis, using the ultra-high-performance liquid chromatography–quadrupole time-of-flying (UPLC–QToF) technique. We assayed flower buds in different stages of endodormancy in four almond cultivars with different flowering times: the extra-early Desmayo Largueta, the late Antoñeta, the extra-late Penta, and the ultra-late Tardona. An orthogonal projection to latent-structure discriminant-analysis model was created to observe differences between endodormant and ecodormant flower buds. The metabolites showing the most significant variation were searched against the Metlin, HMDB, and KEGG libraries, which allowed us to identify 87 metabolites. These metabolites were subsequently assigned to specific pathways, such as abscisic acid biosynthesis, phenylpropanoid biosynthesis, and D-sorbitol metabolism, among others. The two metabolites that exhibited the most significant variations in all the cultivars studied with fold changes of up to 6.49 were ascorbic acid and prunasin. For the first time, these two metabolites have been proposed as potential biomarkers for endodormancy release in almond. Given the high synteny present between the Rosaceae species, these results could be extrapolated to other important crops like peach, plum, cherry, or apricot, among others.

Ethephon-Mediated Bloom Delay in Peach Is Associated With Alterations in Reactive Oxygen Species, Antioxidants, and Carbohydrate Metabolism During Dormancy

“…The ROS detoxification system is crucial for fatty acid unsaturation during dormancy ( Norman et al, 1991 , Erez et al, 1997 , Gabay et al, 2019 ). The elevated levels of non-enzymatic antioxidants, e.g., glutathione and ascorbate, are closely associated with the endodormancy release in deciduous species, including apple, peach, and almond ( Wang and Faust, 1990 ; Siller-Cepeda et al, 1992 ; Guillamón et al, 2020 ). In the present study, it was observed that ET treatment did not alter the GSH metabolism ( Figures 2C – E ) but maintained high H 2 O 2 levels for an extended period during endodormancy which could have a negative effect on fatty acid unsaturation.…”

“…Therefore, the balance between ROS production and scavenging is crucial for efficient fatty acid unsaturation and subsequently dormancy release and bud break. Indeed, higher levels of glutathione and ascorbate, the key scavengers of ROS, were found to be closely associated with the dormancy release in deciduous species, including peach and almond ( Siller-Cepeda et al, 1992 ; Guillamón et al, 2020 ). The upregulation of the oxidation-reduction process during the endodormancy release and bud break has also been demonstrated in many other deciduous species ( Beauvieux et al, 2018 ; Yu et al, 2020 ).…”

Identification of early and late flowering time candidate genes in endodormant and ecodormant almond flower buds

“…2019 ). Even more recently, phenylpropanoid compounds as cinnamic, p-coumaric, caffeic and ferulic acid have been described in the release of endodormancy in almond flower buds ( Guillamón et al. 2020 ).…”

Interaction of gibberellin and other hormones in almond anthers: phenotypic and physiological changes and transcriptomic reprogramming

“…A suitable temperature is a necessary condition for the survival of organisms, but the adaptability of various organisms to changes in temperature differs considerably 1 . A significant difference between plants and other multicellular complex organisms is that plants live in a fixed state.…”