In vitro acclimation to prolonged metallic stress is associated with modulation of antioxidant responses in a woody shrub Daphne jasminea

Abstract

The study aimed at distinguishing antioxidant responses conditioning acclimation status to metallic stress in a shoot culture of a woody plant Daphne jasminea. Growth, organogenesis, metal accumulation, oxidative stress level and antioxidant responses were compared in the long-term treated shoots (Lt lines) and short-term treated (St lines) with Cd, Ni and Pb in relation to control shoots. Growth rate and organogenic potential were higher in the long-term treated Lt Cd and Lt Pb lines than in respective short-term treated St lines. Lt Ni line proliferated less effectively than St Ni line, whereas biomass accretion was similar in both Ni lines. All heavy metal (HM)-exposed shoots suffered from oxidative stress, however, it was more severe in St than in Lt lines. In the long-term treated lines three major factors were associated with the acclimation status: activity of peroxidase (POD) and accumulation of anthocyanins and carotenoids. POD activity was 4-1.5-times higher in Lt lines than in the control one. Anthocyanin content nearly tripled, while carotenoid content doubled in Lt lines. Other elements of antioxidant system, CAT and SOD, glutathione, ascorbic acid and proline, complemented the action of the "major players" in long-term treated Lt lines depending on heavy metal type. Short-term treated lines responded by accumulation of proteins and a decline in catalase activity. The study demonstrated that long-term heavy metal treatment can be considered acclimation strategy, during which substantial modulation of the antioxidant system occurs. Due to orchestrated action of cytosolic POD, vacuolar anthocyanins and membrane-bound carotenoids HM toxicity could be counteracted in various cellular compartments. Key message Acclimation to heavy metal exposure in D. jasminea shoot cultures involves modulation of antioxidant activity and is conditioned by an orchestrated action of cellular peroxidases, vacuolar anthocyanins and membrane-bound carotenoids.

Phytoremediation of soils polluted with heavy metals in the vicinity of the Zenica steel mill in Bosnia and Herzegovina: potential for using native flora

“…The majority of studies report that ion homeostasis in plasmatic compartments is of great importance for the acclimation of plants to heavy metals stress conditions (Wiszniewska et al 2019;Anwar and Kim 2020). Low toxic heavy metal ion activities in cytosol, nucleoplasm, mitochondria and other plasmatic compartments ensure regular functioning of metabolic processes and may be achieved mainly by vacuolar compartmentalization.…”

Response of physiological parameters in Dionaea muscipula J. Ellis teratomas transformed with rolB oncogene

“…To support this hypothesis, the carotenoid and phenolic acid content of Venus flytrap teratomas was examined, which together with glutathione are an important element of the non-enzymatic antioxidant system in plants [ 34 ]. Both examined clones had an increased carotenoid content compared to the control.…”

“…SOD activity was measured according to Hwang et al [ 54 ], with modifications [ 34 ]. The enzyme extract was mixed with methionine, nitro blue tetrazolium, and riboflavin.…”

Priming Strategies for Benefiting Plant Performance under Toxic Trace Metal Exposure

“…In studies on plant physiology, the term priming usually means short-lasting preconditioning or pretreatment with specific compounds, biological agents or physical factors in order to achieve enhanced survivability and efficient action of defense mechanisms under subsequently encountered stress [ 17 , 18 ]. In contrast, defense responses developed during long periods of stress duration (chronic stress, often of a gradually increasing intensity), to which plant metabolism adjusts, are attributed to the acclimation phenomenon [ 15 , 19 ]. Acclimated plants maintain a higher content of stress-protective compounds and therefore are well equipped for subsequent stress episodes.…”

“…Considering metallic stress, in vitro culture systems focus on developing plant tolerance to chronic exposure to trace metals, contributing to the acquisition of an acclimation status. As a result of prolonged selection in the presence of stress agents, such as salinity or toxic elements, functioning of plant cells and regenerated plantlets is modified in comparison with non-exposed ones [ 19 , 61 , 62 ]. A hypothetical “priming agent” that induces acclimation to heavy metals in such culture systems has not been identified.…”