Abstract: In order to reveal the mechanism of tobacco leaf light energy utilization and photoprotective systems in aluminum (Al)-induced reactive oxygen species metabolism, two different Al-tolerant tobacco cultivars Yunyan 100 (Al-tolerant) and Yunyan 105 (Al-sensitive) were used to study effects of four Al concentrations (0, 50, 100, 200 μmol/L) on plant growth, reactive oxygen content, photosynthesis, chlorophyll fluorescence characteristics, photorespiration, activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) in leaves of tobacco cultivar with solution culture method. The results showed that increasing Al concentrations significantly decreased the leaf chlorophyll content, net photosynthetic rate (Pn), maximal photochemical efficiency (Fv/Fm),quantum yield of electron transport at PS Ⅱ (Φ_{PS Ⅱ}) and coefficient of photochemical quenching (qP), increased excess energy of PS Ⅱ photochemistry leading to higher accumulation of leaf O₂^· and H₂O₂, and lower plant biomass, especially in Yunyan 105. With the Al concentrations increased from 0 to 200 μmol/L, the coefficient of non-photochemical quenching (NPQ), photorespiration rate, and activities of SOD and APX were promoted firstly and then reduced again. Compared with Al-sensitive cv. Yunyan 105, Al-tolerant cv. Yunyan 100 remained higher leaf Φ_{PS Ⅱ}, qP, NPQ, photorespiration rate, and activities of SOD and APX under different Al concentrations. These results indicated that tobacco could enhance the tolerance to Al stress by increasing photochemical reaction capacity, heat dissipation, photorespiration and activities of antioxidative enzymes in order to decrease excess energy of PS Ⅱ photochemistry, which prevents or eliminates reactive oxygen accumulation under the low Al concentration.

Key words: Aluminum stress, Reactive oxygen species, Photosynthesis, Chlorophyll fluorescence, Photorespiration, Antioxidant enzyme, Tobacco

CLC Number: 

• Q945.78