| Effects of exogenous hydrogen peroxide on chlorophyll fluorescence parameters and cadmium accumulation characteristics in naked oat under cadmium stress |
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| DOI：10.7606/j.issn.1000-7601.2019.06.10 |
| Key Words: hydrogen peroxide naked oat Cd stress chlorophyll fluorescence parameter cadmium accumulation characteristics |
| Author Name | Affiliation | | LIU Jianxin | University Provincial Key Laboratory for Protection and Utilization of Longdong Bio\|resources in Gansu Province/College of Life Sciences and Technology, Longdong University, Qingyang, Gansu 745000, China | | OU Xiaobin | University Provincial Key Laboratory for Protection and Utilization of Longdong Bio\|resources in Gansu Province/College of Life Sciences and Technology, Longdong University, Qingyang, Gansu 745000, China | | WANG Jincheng | University Provincial Key Laboratory for Protection and Utilization of Longdong Bio\|resources in Gansu Province/College of Life Sciences and Technology, Longdong University, Qingyang, Gansu 745000, China |
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| Abstract: |
| Cadmium (Cd) is one of the most biotoxic heavy metal pollutants. Hydrogen peroxide (H2O2) is a signaling molecule involved in plant response regulation to different stresses, including heavy metal stress. The objective of this study was to analyze the physiological mechanism of exogenous H2O2 mitigating Cd induced stress damage in naked oat (Avena nuda L.) seedlings. Seedlings of naked oat cultivar ‘Dingyou 6’ were used in a sand culture experiment to investigate the effect of spraying H2O2 on seedling growth, leaf xanthophyll cycle, chlorophyll fluorescence parameters, and cadmium accumulation characteristics with 50 mg·L-1 Cd2+ treatment. The results showed that Cd exposure depressed plant growth. However, after foliar\|spraying with 5 mmol·L-1 H2O2, the dry weights of roots and shoots were increased by 18.5% and 26.9%, respectively. In addition, the PSⅡ maximal ph\|otochemistry efficiency (Fv/Fm), practical photochemical efficiency (ΦPSⅡ), photochemical quenching coefficient (qP), photosynthetic system Ⅰ excitation energy distribution coefficient (α), and quotient of absorbed luminous energy used for photochemical action (P) in leaves of naked oat seedlings under Cd stress after foliar\|spraying H2O2 increased by 15.7%, 98.6%, 61.6%, 40.9% and 98.6%, respectively, compared with Cd stress treatment alone. The leaf de\|epoxidation extent of xanthophyll cycle (A+Z)/(V+A+Z), photosynthetic system Ⅱ (PSⅡ) non\|photochemical quenching coefficient (NPQ), regulated energy dissipation Y (NPQ), non\|regulated energy dissipation Y (NO), PSⅡ excitation energy distribution coefficient (β), unbalanced distribution of coefficient deviation on excitation energy between two photosystems (β/α-1), quotient of absorbed luminous energy used for antenna heat dissipation (D), and quotient of absorbed luminous energy used for non\|photochemical dissipation (Ex) in reaction center of PSⅡ decreased by 11.2%, 7.9%, 13.9%, 12.2%, 12.7%, 55.2%, 19.1% and 10.6%, respectively. Moreover, the Cd content and accumulation in roots and shoots increased by 52.0%, 92.4% and 25.2%, respectively, and the transport rate of Cd from roots to shoots decreased by 34.4% after foliar\|spraying H2O2 under Cd stress, but there was no significant change in Cd content in shoots. Therefore, foliar\|spraying H2O2 not only decreased photoinhibition caused by Cd stress through improving PSⅡ photochemical efficiency rather than the xanthophyll cycle\|dependent energy dissipation, but also enhanced the immobilization of Cd in roots and reduced its transportation from root to shoot in naked oat seedlings under Cd stress, thus mitigated the inhibition of Cd stress on seedlings growth and enhanced the tolerance of naked oat to Cd stress. |
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