Antioxidant responses to drought and salinity in Lavandula angustifolia Mill.

Zsolt SZEKELY-VARGA,Oscar VICENTE,Monica BOSCAIU,Sara GONZÁLEZ-ORENGA,Maria CANTOR

doi:10.15835/nbha48412150

Abstract

Drought and salinity are amongst the most damaging environmental stressors that can affect a plant's life cycle, from germination to senescence. In the present study were analysed the responses to salinity and drought in greenhouse-controlled conditions of two varieties of Lavandula angustifolia. Three-month-old lavender seedlings were subjected to water deficit and salt stress (100, 200 and 300 mM NaCl) during a 30-day period. Complementing a previous analysis focused on stress tolerance mechanisms based on the regulation of ion transport and the synthesis of osmolytes, we have now evaluated the effects of the water deficit and salt treatments on the generation of secondary oxidative stress, by measuring malondialdehyde levels, and the activation of antioxidant systems, both non-enzymatic and enzymatic, determining total phenolic compounds and flavonoids contents and calculating superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase specific activities, respectively, in extracts of control and stressed plants. The results obtained confirm that both lavender varieties react in the same way to the applied stress treatments, activating the same antioxidant responses. However, some differences were observed when comparing the specific mechanisms triggered by each type of stress. Thus, the oxidative stress induced under drought conditions was counteracted by accumulation of phenolic compounds and flavonoids, without apparent involvement of antioxidant enzymes. Salt stress, on the other hand, in addition to an increase in flavonoid levels also induced superoxide dismutase and catalase activities. These antioxidant responses are likely to contribute to the relatively high tolerance (as compared to most crops) of lavender to drought and salinity.

Highlights

Drought is becoming a major environmental challenge in many areas of the world, imposing the need for irrigation, which is eventually causing soil salinisation (Fahad et al, 2017)
Complementing a previous analysis focused on stress tolerance mechanisms based on the regulation of ion transport and the synthesis of osmolytes, we have evaluated the effects of the water deficit and salt treatments on the generation of secondary oxidative stress, by measuring malondialdehyde levels, and the activation of antioxidant systems, both non-enzymatic and enzymatic, determining total phenolic compounds and flavonoids contents and calculating superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase specific activities, respectively, in extracts of control and stressed plants
Non-enzymatic antioxidants Total phenolic compounds (TPC) (Figure 2a) and total flavonoids (TF) (Figure 2b) were quantified in all leaf samples collected from the two lavender varieties in the presence of the indicated NaCl concentrations (100, 200 and 300 mM NaCl) or under water deficit stress (WS) for 30 days

Summary

Introduction

Drought is becoming a major environmental challenge in many areas of the world, imposing the need for irrigation, which is eventually causing soil salinisation (Fahad et al, 2017). Such environmental changes, Received: 09 Nov 2020. Received in revised form: 04 Dec 2020. Not Bot Horti Agrobo 48(4):1980-1992 which pose a serious threat to agriculture, have been reported in Romania (Croitoru et al, 2016; Irimia et al, 2018; Prăvălie et al, 2020)

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