Photosynthesis, lipid peroxidation, and antioxidative responses of Helianthus annuus L. against chromium (VI) accumulation

Abstract

The present study was performed to address how Cr(VI) posed its toxicities on photosynthesis, lipid peroxidation, and its retaliation by antioxidative system of Helianthus annuus L. during Cr(VI) accumulation. For this, a pot experiment was performed wherein three different concentrations viz, 15, 30, and 60 mg Cr(VI) kg⁻¹ soil were applied to Helianthus annuus L. at the time of seeds sowing. The results revealed that Cr(VI) accumulation was two to three folds higher in roots than in shoots which suggests that root is the major site for Cr(VI) accumulation. It was observed that with increasing doses of Cr(VI), growth indices hampered significantly, along with closure of stomata and damaged guard and epidermal cells. Photosynthetic pigments (chlorophyll a, chlorophyll b, carotenoids), leaf gaseous exchange parameters (A, E, GH₂O), and PSII efficiency (F_v/F_m) worsened under Cr(VI) toxicity in dose dependent manner. Cr(VI) accumulation intensified the lipid peroxidation, too by triggering the MDA and H₂O₂ production, however, the plant responded well against the lipid peroxidation by enhancing the coordinated action of enzymatic (SOD, APX, GR) and non-enzymatic (GSH, AsA) antioxidants. In a nutshell, Helianthus annuus L. could be used as a potential Cr(VI) accumulator because of its good tolerance strategies against Cr(VI) toxicities.

NOVELTY STATEMENT The results revealed that Cr(VI) accumulation was two to three folds higher in roots than in shoots which suggests that root is the major site for Cr(VI) accumulation. Photosynthetic pigments, leaf gaseous exchange parameters, and F_v/F_m worsened under Cr(VI) toxicity. Cr(VI) accumulation intensified lipid peroxidation by triggering MDA and H₂O₂ production, however, the plant responded well against the lipid peroxidation by enhancing the coordinated action of enzymatic and non-enzymatic antioxidants. In a nutshell, Helianthus annuus L. could be used as a potential Cr(VI) accumulator because of its good tolerance strategies against Cr(VI) toxicities.

Keywords:

• Cr(VI)
• enzymatic antioxidants
• Helianthus annuus L.
• lipid peroxidation
• non- enzymatic antioxidants
• photosynthesis
• phytoremediation

Acknowledgment

CSS is thankful to the Department of Botany, University of Delhi, India for providing the research facilities. DK acknowledges the Council of Scientific and Industrial Research (CSIR), New Delhi, India for awarding the SRF.

Disclosure statement

No potential conflict of interest was reported by the author(s).