Responsive mechanism of Hemerocallis citrina Baroni to complex saline-alkali stress revealed by photosynthetic characteristics and antioxidant regulation

• Published in: Plant cell reports 2024-07, Vol.43 (7), p.176, Article 176
• Main Authors: Chen, Shuo, Zhou, Qiuxue, Feng, Yuwei, Dong, Yanjun, Zhang, Zixuan, Wang, Yue, Liu, Wei
• Format: Article
• Language: English
• Subjects: Alkalies; Antioxidants; Antioxidants - metabolism; Ascorbic acid; Biomedical and Life Sciences; Biotechnology; Calvin cycle; Cell Biology; Cell membranes; Chlorophyll; Chlorophyll - metabolism; Damage; Electron transfer; Environmental degradation; Enzymatic activity; Enzymes; Gene expression; Gene Expression Regulation, Plant - drug effects; Genes; Glutathione; Hemerocallis citrina; Leaves; Life Sciences; Light-harvesting complex; Membrane permeability; Network analysis; Original Article; Oxidative Stress - drug effects; Peroxiredoxin; Phenotypes; Photosynthesis; Photosynthesis - drug effects; Photosystem; Plant Biochemistry; Plant Leaves - drug effects; Plant Leaves - genetics; Plant Leaves - metabolism; Plant Leaves - physiology; Plant Sciences; Reactive oxygen species; Salinization; Salt Stress; Scavenging; Sodium bicarbonate; Sodium carbonate; Sodium chloride; Sodium sulfate; Soil salinity; Stress; Stress, Physiological - drug effects; Stress, Physiological - genetics; Thioredoxin; Transcriptomics
• ISSN: 0721-7714; 1432-203X; 1432-203X
• DOI: 10.1007/s00299-024-03261-4

Key message Saline-alkali stress induces oxidative damage and photosynthesis inhibition in H. citrina , with a significant downregulation of the expression of photosynthesis- and antioxidant-related genes at high concentration. Soil salinization is a severe abiotic stress that impacts the growth and development of plants. In this study, Hemerocallis citrina Baroni was used to investigate its responsive mechanism to complex saline-alkali stress (NaCl:Na 2 SO 4 :NaHCO 3 :Na 2 CO 3  = 1:9:9:1) for the first time. The growth phenotype, photoprotective mechanism, and antioxidant system of H. citrina were studied combining physiological and transcriptomic techniques. KEGG enrichment and GO analyses revealed significant enrichments of genes related to photosynthesis, chlorophyll degradation and antioxidant enzyme activities, respectively. Moreover, weighted gene co-expression network analysis (WGCNA) found that saline-alkali stress remarkably affected the photosynthetic characteristics and antioxidant system. A total of 29 key genes related to photosynthesis and 29 key genes related to antioxidant enzymes were discovered. High-concentration (250 mmol L −1 ) stress notably inhibited the expression levels of genes related to light-harvesting complex proteins, photosystem reaction center activity, electron transfer, chlorophyll synthesis, and Calvin cycle in H. citrina leaves. However, most of them were insignificantly changed under low-concentration (100 mmol L −1 ) stress. In addition, H. citrina leaves under saline-alkali stress exhibited yellow–brown necrotic spots, increased cell membrane permeability and accumulation of reactive oxygen species (ROS) as well as osmolytes. Under 100 mmol L −1 stress, ROS was eliminate by enhancing the activities of antioxidant enzymes. Nevertheless, 250 mmol L −1 stress down-regulated the expression levels of genes encoding antioxidant enzymes, and key enzymes in ascorbate–glutathione (AsA-GSH) cycle as well as thioredoxin-peroxiredoxin (Trx-Prx) pathway, thus inhibiting the activities of these enzymes. In conclusion, 250 mmol L −1 saline-alkali stress caused severe damage to H. citrina mainly by inhibiting photosynthesis and ROS scavenging capacity.