Profiling as method to identify relevant metabolites for phenological modelling purposes
Final Report Abstract
The aim of this research project was to identify metabolites in cherry buds that are involved in the induction, maintenance and release of dormancy and that confirm the end of dormancy and the beginning of ontogenetic development. To this end, tiered metabolite profiling (untargeted, targeted) was carried out to determine which groups of substances show significant and physiologically justified changes in buds between dormancy phases. Representatives of these groups of compounds were used to gain a deeper understanding of the processes during dormancy and to investigate their relevance for phenological modelling. As an example, cherry flower buds of the cultivar Summit were sampled weekly from October to April over a period of nine years. As a result of the "untargeted global metabolite profiling", 445 metabolites were identified in cherry buds that could be assigned to different groups of substances, including phytohormones, amino acids, carbohydrates, lipids, nucleotides and peptides. The temporal increase and decrease in the number of metabolites during the observation period could indicate both anabolic and catabolic metabolic processes. A differentiated view of the number of metabolites confirmed the cessation of biological activity (e.g. energy metabolism) before and during ecodormancy and the resumption of metabolic activity with the onset of ontogenetic development. Abscisic acid, chrysin, arabonic acid, pentose acid, sucrose and isoleucine were selected for concentration determination, as they showed significant changes in their intensity between phenological stages, including the unobserved dates for t1 and t1*. Only the phytohormone abscisic acid (ABA), which has a growth and thus developmental inhibitory function during winter dormancy in sweet cherry buds, has been identified as a metabolite that allows physiologically based modelling of ecodormancy. However, knowledge on the establishment, maintenance and release of dormancy is limited. The results of this project provide new insights. The investigations showed that the amount of heat available during ecodormancy (t1-t1*) varies strongly from year to year (998 ± 699 GDH, cv=70 %) and has no significant influence on the flowering date in spring. In addition, it was shown that under controlled conditions during ecodormancy, the heat requirement until flowering is reduced as a function of ABA content in the buds. In contrast, the accumulation of chill units (CP) during ecodormancy does not lead to a reduction in ABA content and is therefore not physiologically supported. The chilling/forcing compensation assumed in parallel phenology models is thus only the physiological expression of a decreasing ABA content in the buds, which reduces on average by about 50 % between t1 and t1*. In summary, the accumulation of chilling units after t1 is not physiologically justified. This approach must lead to erroneous results when using the models under changing climatic conditions, since either the chilling requirement (C*) of the trees to release endodormancy is overestimated, or a non-physiologically justified chilling/forcing compensation is assumed. The results of the project provide some important hints for improving phenological modelling and show a new, physiologically based way to develop a sequential 3-phase phenology model. Although the results of this project should lead to a rethinking of phenological modelling, some aspects related to the environmental control of ABA levels, such as the depth of dormancy, modelling of ABA levels in buds and cultivar differences, need to be further investigated.
Publications
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Response of sweet cherry buds and twigs to temperature changes - evaluated by the determination of the degradation and synthesis of sucrose. Horticultural Science, 48(4), 149-157.
Götz, Klaus-Peter & Chmielewski, Frank-Michael
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ABA and Not Chilling Reduces Heat Requirement to Force Cherry Blossom after Endodormancy Release. Plants, 11(15), 2044.
Chmielewski, Frank-M. & Götz, Klaus-Peter
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Ecodormancy modelling - some new clues after 8 years of research. Phenology Conference, Avignon 20-24 June 2022, Abstract Book
Chmielewski FM, Götz KP
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Metabolites in Cherry Buds to Detect Winter Dormancy. Metabolites, 12(3), 247.
Chmielewski, Frank-M. & Götz, Klaus-P.
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Phytohormones in Sweet Cherry Buds During Winter Rest and Bud Development. Journal of Plant Growth Regulation, 42(4), 2519-2529.
Götz, Klaus-Peter; Chmielewski, Frank-M.; Tarkowská, Danuše; Pěnčík, Aleš & Novák, Ondřej
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A physiological model for cherry blossom, Oral presentation on the International Congress of Biometeorology in Tempe, Arizona, 14-17 May 2023
Chmielewski FM, Götz KP
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Metabolites That Confirm Induction and Release of Dormancy Phases in Sweet Cherry Buds. Metabolites, 13(2), 231.
Götz, Klaus-P. & Chmielewski, Frank-M.
