Enzyme activity in the micropylar region of Melanoxylon brauna Schott seeds during germination under heat stress conditions

Abstract

Recent studies indicate that global temperatures will rise substantially in the 21st century, leading to the extinction of several plant species, as plant metabolism and germination are greatly affected by temperature. Melanoxylon brauna, a tree species native to the Atlantic Forest that occurs from northeastern to southeastern Brazil, is one of the many species threatened by global warming. Despite the economic and ecological importance of M. brauna, studies investigating the influence of heat stress on seed germination and biochemical responses are still incipient. This study aimed to evaluate enzyme activity in the micropylar region of M. brauna seeds during germination under heat stress conditions. Endo-β-mannanase, α-galactosidase, polygalacturonase, pectin methylesterase, pectin lyase, total cellulase, 1,3-β-glucosidase, and 1,4-β-glucosidase activities were determined in micropyles of seeds imbibed for 24, 48 and 72 h at 25, 35 and 45 °C. Seed germination was highest at 25 °C. Endo-β-mannanase activity was not detected under any of the experimental conditions, but imbibition temperature had a significant effect on the activity of all other enzymes.

Response Mechanisms of Woody Plants to High-Temperature Stress

“…Some woody plant seeds have dormancy mechanisms to ensure that seeds germinate under suitable environmental conditions; high-temperature stress may interrupt or change the dormancy state of seeds, resulting in the abnormal germination of seeds [10]. In addition, high-temperature stress can also lead to lipid peroxidation and protein inactivation and affect the enzyme activity of seeds, thus, increasing the seed mortality [11]. To avoid the negative impact of high-temperature stress on the seed germination and seedling growth of woody plants, some measures can be taken, such as maintaining appropriate temperature and humidity conditions at the seed germination stage, providing sufficient water and nutrients and avoiding exposure to a high-temperature environment.…”

Mobilization of Storage Reserves in Dalbergia spruceana Benth. (Fabaceae) Seeds During Germination at Different Temperatures

“…Temperature stress conditions, in contrast, may reduce the activity of enzymes involved in reserve degradation and affect membrane selectivity, precluding the use of essential metabolites for germination (Santos et al, 2019). Temperature can also have an effect on the metabolites used in the germination process as an adaptive strategy to survive thermal variations (Félix et al, 2020;Santos et al, 2020).…”