Responses of Physiology, Photosynthesis, and Related Genes to Saline Stress in Cornus hongkongensis subsp. tonkinensis (W. P. Fang) Q. Y. Xiang

Abstract

Cornus hongkongensis subsp. tonkinensis (W. P. Fang) Q. Y. Xiang is a native evergreen species with high ornamental value for abundant variations in leaf, bract, fruit, and tree gesture. To broaden its cultivation in coastal saline soil, salt damage and survival rate, physiological responses, photosynthetic performance, and related genes were evaluated for annual seedlings exposed to 0.3% salt (ST) concentrations for 60 days. Syndromes of salt damage were aggravated, and the survival rate decreased with prolonged stress duration; all stressed seedlings displayed salt damage, and 58.3% survived. Under short-term saline stress (5 d), marked increases in malondialdehyde (MDA), relative electrical conductivity (REC), and decreases in superoxide dismutase (SOD), photosynthetic rate (Pn), stomatal conductance (gs), and internal carbon dioxide concentration (Ci) were recorded. The stable leaf water use efficiency (WUE) and chlorophyll content were positive physiological responses to ensure photosynthetic performance. Meanwhile, the expression levels of genes related to photosystem II (psbA) and photorespiration (SGAT and GGAT) were upregulated, indicating the role of photorespiration in protecting photosynthesis from photoinhibition. After 30 days of stress (≥30 d), there was a significant increase in MDA, REC, soluble sugar (SS), soluble protein (SP), and Ci, whereas descending patterns in Pn, gs, WUE, the maximal photochemical efficiency of photosystem II (Fv/Fm), and potential activities of PSII (Fv/F0) occurred in salt-stressed seedlings, compared with CK. Meanwhile, the expression levels of related genes significantly dropped, such as psbA, LFNR, GGAT, GLYK, and PGK, indicating photoinhibition and worse photosynthetic performance. Our results suggest that the moderate salt tolerance of C. hongkongensis subsp. tonkinensis mostly lies in a better photosynthetic system influenced by active photorespiration. Hence, these results provide a framework for better understanding the photosynthetic responses of C. hongkongensis subsp. tonkinensis to salt stress.

Exogenous melatonin mitigates saline‐alkali stress by decreasing DNA oxidative damage and enhancing photosynthetic carbon metabolism in soybean (Glycine max [L.] Merr.) leaves

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High strength and light weight polyamide 6/carbon fiber composite foams for electromagnetic interference shielding

“…Nevertheless, when conducting fillers were added to the polymer matrix to give conductivity to the polymer composites, they have a good EMI shielding performance. [2][3][4] After adding fillers such as Fe 3 O 4 , 5 carbon fiber, 6 carbon nanotube, 7 and graphene 8 into the polymer matrix, the composite materials have excellent electrical conductivity and high-temperature resistance, anti-aging and high mechanical strength. This is becoming a new direction for the development of polymer electromagnetic shielding materials.…”

Growth, Physiological and Biochemical Response of Chickpea Cultivars to Different Levels of Salinity Stress

“…Salinity stress (SS) is a challenging abiotic stress which considerably reduced the seed germination, plant growth and metabolic activities (Carbajal-Vázquez et al, 2022) and productivity (Rajabi et al, 2020). The high concentration of salts induced detrimental impacts on plant physiology and disturbs the ionic homeostasis, plant hormones balance and altered plants growth and subsequent development (Azzam et al, 2022;Yuan et al, 2022). Salinity stress reduces the synthesis of chlorophyll contents, photosynthetic efficiency and it disturbs plant water relationships, membrane stability and accumulation of different osmolytes (Dustgeer et al, 2021;Rehman et al, 2021).…”