Water deficit‐induced oxidative stress affects artemisinin content and expression of proline metabolic genes in Artemisia annua L.

Abstract

Water stress is one of the most critical abiotic stresses that restricts growth, development, and alters physiological and biochemical mechanisms of plant. The effects of long‐term water shortage‐induced oxidative stress on morphophysiological parameters, proline metabolic genes, and artemisinin content were studied in Artemisia annua L. under greenhouse conditions. Plant growth, biomass accumulation, relative water content, and chlorophyll content were reduced under drought. Leaf water potential ranged from −0.3248 MPa to −1.22 MPa in stress conditions. Increased levels of proline accumulation, protein concentration, and lipid peroxidation were detected in water‐stressed plants. Stage‐dependent increases in activity of antioxidants including superoxide dismutase, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase, and dehydroascorbate reductase were observed. The expression of proline biosynthetic genes including pyrroline‐5‐carboxylase synthase1, 1‐pyrroline‐5‐carboxylase synthase2, and 1‐pyrroline‐5‐carboxylase reductase was induced, while the ornithine aminotransferase transcript showed a variable response and the expression of proline catabolic genes including proline dehydrogenase1, proline dehydrogenase1, and proline 5‐carboxylate dehydrogenase was reduced by water stress. Our results indicate that the glutamine pathway is predominant under drought stress in A. annua and a reduction of catabolic gene expression is adopted as a defense strategy in adverse conditions. Higher expression of biosynthetic genes and lower expression of catabolic genes at the preflowering stage confirmed the important role of proline in flower development. Artemisinin content decreased owing to water stress, but the slightly higher amounts were detected in leaves of severely stressed plants compared with moderately stressed plants. The artemisinin content of A. annua might be regulated by controlling irrigation regimes.

Nitrate reductase is required for salicylic acid‐induced water stress tolerance of pepper by upraising the AsA‐GSH pathway and glyoxalase system

“…Water stress enhanced the activity of DHAR in the pepper seedlings. Similar results have already been reported in Agropyron cristatum (Shan and Liang 2010) and Artemisia annua (Soni and Abdin 2017) under WS. The application of SA caused further elevation in DHAR activity in mustard (Alam et al 2013) as is also seen in this study.…”

Chlorophyll-a Fluorescence Analysis Reveals Differential Response of Photosynthetic Machinery in Melatonin-Treated Oat Plants Exposed to Osmotic Stress

“…The P5CS1 expression was reported to be highly activated, while PDH isoforms were moderately stimulated during drought conditions resulting in increased proline levels in the tobacco plants [29]. Another study demonstrated significantly induced levels of the major proline biosynthesis genes, including P5CS1 and PDH1 in Artemisia plants subjected to drought stress [30]. Similar findings were recorded in our study, where the melatonin applied appeared to impede the drastic stimulation of the PDH1 and P5CS1 expressions in the MPEG plants compared to that of the PEG plants ( Figure 2C,D).…”

Melatonin Positively Influences the Photosynthetic Machinery and Antioxidant System of Avena sativa during Salinity Stress

“…Proline plays multiple roles in higher plants, including maintenance of membrane integrity, removal of ROS, regulation of osmotic pressure, and acting as an osmoprotectant against a range of abiotic stresses, including high salinity [33]. An increase in the endogenous proline content is known to confer abiotic stress tolerance and is associated with upregulation of the P5CS1 gene and downregulation of the PDH gene [34,35]. P5CS1 is involved in the first step of proline synthesis and catalyzes the conversion of L-glutamic acid to glutamate-5-semialdehyde [33].…”