Abstract
BackgroundThe CIPKs are a group of plant-specific Ser/Thr protein kinases acting in response to calcium signaling, which plays an important role in the physiological and developmental adaptation of plants to adverse environments. However, the functions of halophyte-derived CIPKs are still poorly understood, that limits a potential application of CIPKs from halophytes for improving the tolerance of glycophytes to abiotic stresses.ResultsIn this study, we characterized the NtCIPK11 gene from the halophyte Nitraria tangutorum and subsequently analyzed its role in salt and drought stress tolerance, using Arabidopsis as a transgenic model system. NtCIPK11 expression was upregulated in N. tangutorum root, stem and blade tissues after salt or drought treatment. Overexpressing NtCIPK11 in Arabidopsis improved seed germination on medium containing different levels of NaCl. Moreover, the transgenic plants grew more vigorously under salt stress and developed longer roots under salt or drought conditions than the WT plants. Furthermore, NtCIPK11 overexpression altered the transcription of genes encoding key enzymes involved in proline metabolism in Arabidopsis exposed to salinity, however, which genes showed a relatively weak expression in the transgenic Arabidopsis undergoing mannitol treatment, a situation that mimics drought stress. Besides, the proline significantly accumulated in NtCIPK11-overexpressing plants compared with WT under NaCl treatment, but that was not observed in the transgenic plants under drought stress caused by mannitol application.ConclusionsWe conclude that NtCIPK11 promotes plant growth and mitigates damage associated with salt stress by regulating the expression of genes controlling proline accumulation. These results extend our understanding on the function of halophyte-derived CIPK genes and suggest that NtCIPK11 can serve as a candidate gene for improving the salt and drought tolerance of glycophytes through genetic engineering.
Highlights
The Calcineurin B-like proteins (CBL)-interacting protein kinases (CIPK) are a group of plant-specific Ser/Thr protein kinases acting in response to calcium signaling, which plays an important role in the physiological and developmental adaptation of plants to adverse environments
We found that NtCIPK11 was induced in root, stem and leaf tissues by 500 mM NaCl or 200 mM mannitol, with transcripts preferentially accumulating in leaves
N. tangutorum physiologically responded to salt treatment As a halophyte with adaptability in a salt environment, N. tangutorum has been the focus of studies designed and implemented to investigate the mechanism of salt tolerance using biochemical methods [7, 10, 12] and molecular biology techniques [14, 15, 36]
Summary
The CIPKs are a group of plant-specific Ser/Thr protein kinases acting in response to calcium signaling, which plays an important role in the physiological and developmental adaptation of plants to adverse environments. Soil salinity and drought are critical environmental threats to plant development that limit plant growth by negatively affecting the availability, transportation, and partitioning of nutrients and water. These effects are threatening to decline crop productivity worldwide and increase the pace of soil desertification, further affecting the ecological balance [1]. N. tangutorum is a desert halophyte adapted to severe drought and high salinity, and generally grows in arid or semiarid regions with high salinity [7, 8] This species can efficiently alleviate the degree of soil salinity and fix moving sand, playing an important ecological role in environmental balance [8, 9]. The molecular mechanisms underlying the physiological adaptability of N. tangutorum to various stresses need further study [14,15,16]
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