Differences in gas exchange, chlorophyll fluorescence, and modulated reflection of light at 820 nm between two rhododendron cultivars under aluminum stress conditions

• Published in: PloS one 2024-06, Vol.19 (6), p.e0305133
• Main Authors: Zhang, Jing, Xu, Yanxia, Lu, Kaixing, Gong, Zhengyu, Weng, Zhenming, Shu, Pengzhou, Chen, Yujia, Jin, Songheng, Li, Xueqin
• Format: Article
• Language: English
• Subjects: Acidic soils; Acidification; Agricultural production; Aluminum; Aluminum - toxicity; Biology and Life Sciences; Carbon dioxide; Carbon dioxide concentration; Chlorophyll; Chlorophyll - metabolism; Citrus; Citrus fruits; Cultivars; Earth sciences; Ecology and environmental sciences; Electron transport; Electron Transport - drug effects; Electron transport chain; Fluorescence; Gas exchange; Leaves; Light; Light reflection; Oxidation; Photosynthesis; Photosynthesis - drug effects; Photosynthetic activity; Photosystem I; Photosystem I Protein Complex - metabolism; Photosystem II; Photosystem II Protein Complex - metabolism; Physical sciences; Plant growth; Plant Leaves - drug effects; Plant Leaves - metabolism; Plastocyanin; Rhododendron - metabolism; Seedlings; Stomata; Stomatal conductance; Stress; Stress, Physiological - drug effects; Toxicity
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0305133

Aluminum (Al) toxicity is an important factor restricting the normal growth of plants in acidic soil. Rhododendron (Ericaceae) can grow relatively well in acidic soil. To uncover the adaptive mechanisms of photosynthesis under Al stress, the influence of Al stress on the photosynthetic activities of Al-sensitive (Baijinpao) and Al-resistant (Kangnaixin) rhododendron cultivars was examined by measuring gas exchange, chlorophyll fluorescence, and the modulated reflection of light at 820 nm. Under Al stress conditions, the net photosynthetic rate and stomatal conductance of the rhododendron leaves decreased, whereas the intercellular CO2 concentration increased. The Al stress treatment damaged the oxygen-evolving complex of the rhododendron seedlings, while also inhibiting electron transport on the photosystem II (PSII) donor side. In addition, the exposure to Al stress restricted the oxidation of plastocyanin (PC) and the photosystem I (PSI) reaction center (P700) and led to the re-reduction of PC+ and P700+. The comparison with Kangnaixin revealed an increase in the PSII connectivity in Baijinpao. Additionally, the donor-side electron transport efficiency was more inhibited and the overall activity of PSII, PSI, and the intersystem electron transport chain decreased more extensively in Baijinpao than in Kangnaixin. On the basis of the study findings, we concluded that Al stress adversely affects photosynthesis in rhododendron seedlings by significantly decreasing the activity of PSII and PSI. Under Al stress, Kangnaixin showed stronger tolerance compared with Baijinpao.