Accelerated ageing induces physiological and biochemical changes in tomato seeds involving MAPK pathways

Abstract

This study was performed to explore the accelerated ageing induced biochemical changes in tomato seeds, as little is known about its regulatory mechanisms. Arrays of factors were explored including Physiological parameters (Germination percentage, seedling vigour, Vigour index), Biochemical parameters (Determination of reducing sugar and soluble protein analysis, lipid peroxidation assay, enzymatic antioxidant system) and DNA extraction and analysis. Vigour and germination index declined with increased ageing period, whereas germination loss became more accentuate depicted by mean germination times. Growth parameters as length of root/shoot and weight (fresh/dry) also decreased with ageing. In aged seeds, increased glucose content indicated the occurrence of sugar hydrolysis. Consequently, Amadori products increased during ageing. Thiobarbituric acid-reactive products (TBA) increased as a sign of the lipid peroxidation. Decrease in the antioxidant enzyme activity and soluble protein content suggested increased protein oxidation and loss of functional properties. DNA degradation was also illustrated by quantitative and qualitative analyses. Analysis of pivotal factor involved in stress signaling i.e. Mitogen-Activated Protein Kinases (MAPKs) was done for the first time in tomato seeds. Results showed the upregulation of two MAPKs i.e. MPK-3 and -6. The outcomes of the study suggest that network of various redox factors and signals contributes to the ageing in tomato seeds with the involvement of the MAPK pathway.