Silicon-mediated changes in polyamine and 1-aminocyclopropane-1-carboxylic acid are involved in silicon-induced drought resistance in Sorghum bicolor L

• Published in: Plant physiology and biochemistry Vol. 80; pp. 268 - 277
• Main Authors: Yin, Lina, Wang, Shiwen, Liu, Peng, Wang, Wenhua, Cao, Dan, Deng, Xiping, Zhang, Suiqi
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 01.07.2014; Elsevier
• Subjects: 1-Aminocyclopropane-1-carboxylic acid; Amino Acids, Cyclic - metabolism; Biological and medical sciences; Drought stress; Droughts; Ethylene; Fundamental and applied biological sciences. Psychology; Plant physiology and development; Polyamines; Polyamines - metabolism; Seedlings - drug effects; Seedlings - metabolism; Seedlings - physiology; Silicon; Silicon - pharmacology; Sorghum; Sorghum - drug effects; Sorghum - metabolism; Sorghum - physiology; Drought stress; Sorghum; Silicon; 1-Aminocyclopropane-1-carboxylic acid; Polyamines; Ethylene; Monocotyledones; 1-Aminocyclopropanecarboxylic acid; Polyamine; Induced resistance; Water stress; Cereal crop; Sorghum bicolor; Plant physiology; Carboxylic acid; Gramineae; Drought resistance; Angiospermae; Plant growth substance; Spermatophyta; Drought
• ISSN: 0981-9428; 1873-2690
• DOI: 10.1016/j.plaphy.2014.04.014

The fact that silicon application alleviates drought stress has been widely reported, but the mechanism it underlying remains unclear. Here, morphologic and physiological changes were investigated in sorghum (Sorghum bicolor L.) seedlings treated with silicon and exposed to PEG-simulated drought stress for seven days. Drought stress dramatically decreased growth parameters (biomass, root/shoot ratio, leaf area, chlorophyll concentration and photosynthetic rate), while silicon application reduced the drought-induced decreases in those parameters. Leaf relative water content and transpiration rate were maintained at high levels compared to those in seedlings without silicon. The soluble sugar contents were increased, but the proline contents and the osmotic potential were decreased, showing that osmotic adjustment did not contribute to the silicon induced-drought resistance. Furthermore, levels of both free and conjugated polyamines (PAs) levels, including putrescine, spermidine and spermine, were all found to be increased by silicon under drought stress both in leaf and root. Meanwhile, 1-aminocyclopropane-1-carboxylic acid (ACC), the precursor of ethylene, was markedly decreased by supplemental silicon. Several key PA synthesis genes were upregulated by silicon under drought stress. These results suggest that silicon improves sorghum drought resistance by mediating the balance of PAs and ethylene levels. In leaf, the increased PAs and decreased ACC help to retard leaf senescence. In root, the balance between PAs and ACC participates in the modulation of root plasticity, increases the root/shoot ratio, and contributes to an increase in water uptake. These results suggest that silicon increases drought resistance through regulating several important physiological processes in plants. •Silicon alleviated drought induced growth inhibition and water deficiency.•Silicon retards the leaf senescence and increases the root water uptake.•Polyamines contents were increased by silicon under drought stress in plant tissues.•Contents of 1-aminocyclopropane-1-carboxylic acid were decreased by silicon.•Polyamines and ethylene are involved in silicon induced drought resistance.