期刊
CHEMOSPHERE
卷 308, 期 -, 页码 -出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.chemosphere.2022.136348
关键词
Citrus sinensis; Copper -tolerance; Copper uptake; Root exudates; Root -induced alkalization
资金
- National Key and Development Program of China
- National Natural Science Foundation of China
- Earmarked Fund for China Agriculture Research System
- [2018YFD1000305]
- [32072511]
- [CARS -26-01A]
Copper (Cu) excess is common in citrus orchards. This study investigated Cu-induced release of root exudates and its role in plant Cu-tolerance using sweet orange seedlings. The results showed that root-induced alkalization and Cu-stimulated release of root exudates played a key role in increasing root Cu accumulation and reducing Cu uptake and phytotoxicity.
Copper (Cu) excess is often observed in old Citrus orchards. Little information is available on the characterization of Cu-induced-release of root exudates and their possible roles in plant Cu-tolerance. Using sweet orange [Citrus sinensis (L.) Osbeck cv. Xuegan] seedlings as materials, we investigated the impacts of 0, 0.5, 25, 150, 350, 550, 1000, 2000 or 5000 mu M CuCl2 (pH 4.8) on Cu uptake, root exudates [malate, citrate, total phenolics (TP), total soluble sugars (TSS) and total free amino acids (TFAA)], electrolyte leakage and malondialdehyde, and solution pH under hydroponic conditions; the time-course of root exudates and solution pH in response to Cu; and the impacts of protein synthesis and anion-channel inhibitors, and temperature on Cu-induced-secretion of root exudates and solution pH. About 70% of Cu was accumulated in 0 and 0.5 mu M Cu-exposed roots, while over 97% of Cu was accumulated in >= 25 mu M Cu-exposed roots. Without Cu, the seedlings could alkalize the solution pH from 4.8 to above 6.0. Cu-stimulated-secretion of root exudates elevated with the increment of Cu concentration from 0 to 1000 mu M, then decreased or remained unchanged with the further increment of Cu concentration, while root electrolyte leakage and malondialdehyde (root-induced alkalization) increased (lessened) with the increment of Cu concentration from 0 to 5000 mu M. Further analysis indicated that Cu-stimulated-secretion of root exudates was an energy-dependent process and could repressed by inhibitors, and that there was no discernible delay between the onset of exudate release and the addition of Cu. To conclude, both root-induced alkalization and Cu-stimulated-release of root exudates played a key role in sweet orange Cu-tolerance via increasing root Cu accumulation and reducing Cu uptake and phytotoxicity.
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