Exogenous hydrogen sulphide alleviates copper stress impacts in Artemisia annua L.: Growth, antioxidant metabolism, glandular trichome development and artemisinin biosynthesis.

A supply of plant micronutrients (some of which are metals) is necessary to regulate many plant processes; their excess, however, can have detrimental consequences and can hamper plant growth, physiology and metabolism.Artemisia annua is an important crop plant used in the treatment of malaria. In this investigation, the physio‐biochemical mechanisms involved in exogenous hydrogen sulphide‐mediated (H2S) alleviation of copper (Cu) stress in A. annua were assessed..Two different levels of Cu (20, 40 mg·kg−1), one H2S treatment (200 µm) and their combinations were introduced while one set of plants was retained as control.Results showed that the presence of excess Cu in the soil reduced growth and biomass, photosynthetic parameters, chlorophyll content and fluorescence, gas exchange parameters and induced antioxidant enzyme activity. Copper stress enhanced the production of thiobarbituric acid reactive substances (TBARS) and increased Cu content in both roots and shoots of affected plants. Exogenous application of H2S restored the physio‐biochemical characteristics of Cu‐treated A. annua plants by reducing lipid peroxidation and enhancing the activity of antioxidant enzymes in Cu‐stressed plants as compared with the controls.Hydrogen sulphide also reduced the Cu content in different plant parts, increased photosynthetic efficiency, trichome density, average area of trichomes and artemisinin content. Therefore, our results provide a comprehensive assessment of the defensive role of H2S in Cu‐stressed A. annua. [ABSTRACT FROM AUTHOR]