Jayakumar Bose1, Ana Rodrigo-Moreno2, Diwen Lai1, Yanjie Xie1, Wenbiao Shen1, Sergey Shabala3. 1. School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China. 2. School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China. 3. School of Land and Food, University of Tasmania, Hobart, TAS 7001, Australia, LINV, University of Firenze, Viale delle idee, 30, 50019 Sesto Fiorentino, Italy and College of Life Sciences, Laboratory Centre of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China Sergey.Shabala@utas.edu.au.
Abstract
BACKGROUND AND AIMS: The activity of H(+)-ATPase is essential for energizing the plasma membrane. It provides the driving force for potassium retention and uptake through voltage-gated channels and for Na(+) exclusion via Na(+)/H(+) exchangers. Both of these traits are central to plant salinity tolerance; however, whether the increased activity of H(+)-ATPase is a constitutive trait in halophyte species and whether this activity is upregulated at either the transcriptional or post-translation level remain disputed. METHODS: The kinetics of salt-induced net H(+), Na(+) and K(+) fluxes, membrane potential and AHA1/2/3 expression changes in the roots of two halophyte species, Atriplex lentiformis (saltbush) and Chenopodium quinoa (quinoa), were compared with data obtained from Arabidopsis thaliana roots. KEY RESULTS: Intrinsic (steady-state) membrane potential values were more negative in A. lentiformis and C. quinoa compared with arabidopsis (-144 ± 3·3, -138 ± 5·4 and -128 ± 3·3 mV, respectively). Treatment with 100 mm NaCl depolarized the root plasma membrane, an effect that was much stronger in arabidopsis. The extent of plasma membrane depolarization positively correlated with NaCl-induced stimulation of vanadate-sensitive H(+) efflux, Na(+) efflux and K(+) retention in roots (quinoa > saltbush > arabidopsis). NaCl-induced stimulation of H(+) efflux was most pronounced in the root elongation zone. In contrast, H(+)-ATPase AHA transcript levels were much higher in arabidopsis compared with quinoa plants, and 100 mm NaCl treatment led to a further 3-fold increase in AHA1 and AHA2 transcripts in arabidopsis but not in quinoa. CONCLUSIONS: Enhanced salinity tolerance in the halophyte species studied here is not related to the constitutively higher AHA transcript levels in the root epidermis, but to the plant's ability to rapidly upregulate plasma membrane H(+)-ATPase upon salinity treatment. This is necessary for assisting plants to maintain highly negative membrane potential values and to exclude Na(+), or enable better K(+) retention in the cytosol under saline conditions.
BACKGROUND AND AIMS: The activity of H(+)-ATPase is essential for energizing the plasma membrane. It provides the driving force for potassium retention and uptake through voltage-gated channels and for Na(+) exclusion via Na(+)/H(+) exchangers. Both of these traits are central to plant salinity tolerance; however, whether the increased activity of H(+)-ATPase is a constitutive trait in halophyte species and whether this activity is upregulated at either the transcriptional or post-translation level remain disputed. METHODS: The kinetics of salt-induced net H(+), Na(+) and K(+) fluxes, membrane potential and AHA1/2/3 expression changes in the roots of two halophyte species, Atriplex lentiformis (saltbush) and Chenopodium quinoa (quinoa), were compared with data obtained from Arabidopsis thaliana roots. KEY RESULTS: Intrinsic (steady-state) membrane potential values were more negative in A. lentiformis and C. quinoa compared with arabidopsis (-144 ± 3·3, -138 ± 5·4 and -128 ± 3·3 mV, respectively). Treatment with 100 mm NaCl depolarized the root plasma membrane, an effect that was much stronger in arabidopsis. The extent of plasma membrane depolarization positively correlated with NaCl-induced stimulation of vanadate-sensitive H(+) efflux, Na(+) efflux and K(+) retention in roots (quinoa > saltbush > arabidopsis). NaCl-induced stimulation of H(+) efflux was most pronounced in the root elongation zone. In contrast, H(+)-ATPase AHA transcript levels were much higher in arabidopsis compared with quinoa plants, and 100 mm NaCl treatment led to a further 3-fold increase in AHA1 and AHA2 transcripts in arabidopsis but not in quinoa. CONCLUSIONS: Enhanced salinity tolerance in the halophyte species studied here is not related to the constitutively higher AHA transcript levels in the root epidermis, but to the plant's ability to rapidly upregulate plasma membrane H(+)-ATPase upon salinity treatment. This is necessary for assisting plants to maintain highly negative membrane potential values and to exclude Na(+), or enable better K(+) retention in the cytosol under saline conditions.
Authors: Romola Davenport; Richard A James; Anna Zakrisson-Plogander; Mark Tester; Rana Munns Journal: Plant Physiol Date: 2005-02-25 Impact factor: 8.340
Authors: Franceli R Kulcheski; Régis Côrrea; Igor A Gomes; Júlio C de Lima; Rogerio Margis Journal: Front Plant Sci Date: 2015-06-16 Impact factor: 5.753