Functional analysis of McSnRK1 (SNF1-related protein kinase 1) in regulating Na/K homeostasis in transgenic cultured cells and roots of halophyte Mesembryanthemum crystallinum
Transgenic callus and roots of ice plant with altered SnRK1 function were established using Agrobacterium-mediated transformation. The role of McSnRK1 in controlling Na+ influx and Na/K ratio was demonstrated.
SnRK1 kinases (SNF1-related protein kinase1) control metabolic adaptation during energy deprivation and regulate protective mechanisms against environmental stress. Yeast SNF1 activates a P-type ATPase, the Na+ exclusion pump, under glucose starvation. The involvement of plant SnRK1 in salt stress response is largely unknown. We previously identified a salt-induced McSnRK1 in the halophyte ice plant (Mesembryanthemum crystallinum). In the current study, the function of McSnRK1 in salt tolerance was analyzed in transgenic cultured cells and roots of ice plant. Ice plant callus constitutively expressed a high level of McSnRK1 and introducing the full-length McSnRK1 did not alter the Na/K ratio at 24 h after 200 mM NaCl treatment. However, interfering with McSnRK1 activity by introducing a truncate McSnRK1 to produce a dominant-negative form of McSnRK1 increased cellular Na+ accumulation and Na/K ratio. As a result, the growth of cultured cells diminished under salt treatment. Hydroponically grown ice plants with roots expressing full-length McSnRK1 had better growth and lowered Na/K ratio compared to the wild-type or vector-only plants. Roots expressing a truncate McSnRK1 had reduced growth and high Na/K ratio under 400 mM NaCl treatment. The changes in Na/K ratio in transgenic cells and whole plants demonstrated the function of SnRK1 in controlling Na+ flux and maintaining Na/K homeostasis under salinity. The Agrobacterium-mediated transformation system could be a versatile tool for functional analysis of genes involved in salt tolerance in the ice plant.
KeywordsIce plant Ion homeostasis Salt stress SnRK1
The authors thank the Hwang and Yen laboratory members for discussion and technical assistance. This research was funded by the Ministry of Science and Technology of Taiwan (MOST 103-2311-B-005-003; MOST 107-2321-B-005-009) and in part by the Ministry of Education, Taiwan, under the Higher Education Sprout Project.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Agarie S, Shimoda T, Shimizu Y, Baumann K, Sunagawa H, Kondo A, Ueno O, Nakahara T, Nose A, Cushman JC (2007) Salt tolerance, salt accumulation, and ionic homeostasis in an epidermal bladder-cell-less mutant of the common ice plant Mesembryanthemum crystallinum. J Exp Bot 58:1957–1967CrossRefGoogle Scholar
- Cosentino C, Di Silvestre D, Fischer-Schliebs E, Homann U, De Palma A, Comunian C, Mauri PL, Thiel G (2013) Proteomic analysis of Mesembryanthemum crystallinum leaf microsomal fractions finds an imbalance in V-ATPase stoichiometry during the salt-induced transition from C3 to CAM. Biochem J 450:407–415CrossRefGoogle Scholar
- Fu H, Park WD (1995) Sink- and vascular-associated sucrose synthase functions are encoded by different gene classes in potato. Plant Cell 7:1369–1385Google Scholar
- Hartmann L, Pedrotti L, Weiste C, Fekete A, Schierstaedt J, Göttler J, Kempa S, Krischke M, Dietrich K, Mueller MJ, Vicente-Carbajosa J, Hanson J, Dröge-Laser W (2015) Crosstalk between Two bZIP signaling pathways orchestrates salt-induced metabolic reprogramming in Arabidopsis roots. Plant Cell 27:2244–2260CrossRefGoogle Scholar
- Konieczny R, Obert B, Bleho J, Novák O, Heym C, Tuleja M, Müller J, Strnad M, Menzel D, Šamaj J (2011) Stable transformation of Mesembryanthemum crystallinum (L.) with Agrobacterium rhizogenes harboring the green fluorescent protein targeted to the endoplasmic reticulum. J Plant Physiol 168:722–729CrossRefGoogle Scholar
- Konieczny R, Banaś AK, Surówka E, Michalec Ż, Miszalski Z, Libik-Konieczny M (2014) Pattern of antioxidant enzyme activities and hydrogen peroxide content during developmental stages of rhizogenesis from hypocotyl explants of Mesembryanthemum crystallinum L. Plant Cell Rep 33:165–177CrossRefGoogle Scholar
- Lambert MJ (1976) Preparation of plant material for estimating a wide range of elements. Australian Research Note 29. Forestry Commission of New South Wales, West Pennant HillsGoogle Scholar
- Pedrotti L, Weiste C, Nägele T, Wolf E, Lorenzin F, Dietrich K, Mair A, Weckwerth W, Teige M, Baena-González E, Dröge-Lasera W (2018) Snf1-RELATED KINASE1-controlled C/S1-bZIP signaling activates alternative mitochondrial metabolic pathways to ensure plant survival in extended darkness. Plant Cell 30:495–509CrossRefGoogle Scholar
- Rodrigues A, Adamo M, Crozet P, Margalha L, Confraria A, Martinho C, Elias A, Rabissi A, Lumbreras V, González-Guzmán M, Antoni R, Rodriguez PL, Baena-González E (2013) ABI1 and PP2CA phosphatases are negative regulators of Snf1-related protein kinase1 signaling in Arabidopsis. Plant Cell 25:3871–3884CrossRefGoogle Scholar