biologia plantarum

Biologia plantarum 2016, 60:543-554 | DOI: 10.1007/s10535-016-0626-2

Nitrogen deprivation induces cross-tolerance of Poa annua callus to salt stress

C. Z. Zhao¹, P. Li², X. M. Wang¹, P. Li¹, X. Y. Wang¹, F. Wang¹, J. F. Wang¹, N. Chang¹, Y. R. Bi^1,*

¹ Ministry of Education Key Laboratory of Cell Activities and Stress Adaptations, School of Life Sciences, Lanzhou University, Lanzhou, P.R. China

² North China Electric Power University, State Grid Corporation, Baoding, Hebei, P.R. China

Alternative respiration pathway (AP) is an important pathway which can be induced by environment stresses in plants. In the present study, we show a new mechanism involving the AP in nitrogen deprivation-induced tolerance of Poa annua callus to salt stress. The AP capacity markedly increased under a 600 mM NaCl treatment or nitrogen deprivation pretreatment and reached a maximum under the nitrogen deprivation pretreatment combined with the NaCl treatment (-N+NaCl). Malondialdehyde (MDA) and H₂O₂ content and Na⁺/K⁺ ratio significantly increased under the 600 mM NaCl treatment but less under the-N+NaCl treatment. Moreover, both the nitrogen deprivation and the NaCl stress stimulated the plasma membrane (PM) H⁺-ATPase activity and increased pyruvate content. The maximal stimulating effect was found under the-N+NaCl treatment. When the AP capacity was reduced by salicylhydroxamic acid (SHAM, an inhibitor of AP), content of MDA and H₂O₂ and Na⁺/K⁺ ratio dramatically increased, whereas PM H⁺-ATPase activity decreased. Moreover, exogenous application of pyruvate produced a similar effect as the nitrogen deprivation pretreatment. The effects of SHAM on the Poa annua callus were counteracted by catalase (a H₂O₂ scavenger) and diphenylene iodonium (a plasma membrane NADPH oxidase inhibitor). Taken together, our results suggest that the nitrogen deprivation enhanced the capacity of AP by increasing pyruvate content, which in turn prevented the Poa annua callus from salt-induced oxidative damages and Na⁺ over-uptake.

Keywords: alternative pathway; catalase; H⁺-ATPase; in vitro culture; malondialdehyde; oxidative stress; SHAM

Subjects: nitrogen deprivation; callus; salt stress; alternative respiration pathway; catalase; malondialdehyde; oxidative stress; salicylhydroxamic acid; ion leakage; hydrogen peroxide; pyruvate

Species: Poa annua

Received: December 24, 2014; Revised: October 22, 2015; Accepted: November 4, 2015; Published: September 1, 2016Show citation