Metabolic pathways operating in deteriorating versus germination-competent cyanide-primed walnut kernels

ABSTRACT: Incubation of physiologically dormant walnut kernels at warm and moist conditions leads to reduced germination and lower viability associated with triacylglycerol depletion, lipase activation and fatty acid accumulation. Cyanide however, releases kernel dormancy and improves germination accompanied with enhanced gluconeogenesis. The hypothesis that the viability loss in aging kernels is mainly due to lipid catabolism-induced oxidative stress and higher respiration was tested in a proteomic study. We used kernels with 15% moisture content aged by controlled deterioration, physiologically dormant non-aged and cyanide-treated germination primed; having low, medium and high germination potentials, respectively. We revealed 155 differentially abundant proteins out of 930 identified ones compared to dry (6% moisture content) kernels. Proteins accumulated in deteriorated kernels mainly belonged to protein folding, translation and degradation, defense, stress response and detoxification, glycolysis and fermentation but less abundant ones were related to gluconeogenesis and amino acid metabolism. Contrastingly, accumulated proteins belonged to gluconeogenesis and oxidative pentose phosphate pathway in germination-primed kernels. Deteriorated kernels also showed increased levels of H2O2, lipid peroxidation, free fatty acids, protein carbonylation, and amino acids, particularly proline but, a lower amount of sucrose and enhanced lipase, catalase, peroxidase and glutamate dehydrogenase activities. Of note, we revealed accumulation of various chaperons and proteins related to detoxification in deteriorated kernels, unlike reports on other aging seeds. Suppressed amino acid metabolism and gluconeogenesis enhanced respiration and oxidative stress in deteriorated kernels, while optimized carbon/energy metabolism promoted germination of primed kernels.

INSTRUMENT(S): LTQ Orbitrap Elite

ORGANISM(S): Juglans Regia (english Walnut)

TISSUE(S): Plant Cell, Seed

SUBMITTER: Maksym Danchenko  

LAB HEAD: Peter Baráth

PROVIDER: PXD040462 | Pride | 2024-02-23

REPOSITORIES: Pride