Calcium-mediated adaptive responses to low phosphorus stress in Chinese fir.

Rashid, Muhammad Haroon U.; Tigabu, Mulualem; Chen, Haifeng; Farooq, Taimoor Hassan; Ma, Xiangqing; Wu, Pengfei

Key message: Ca2 induces adaptive response to low P stress through increased root growth and expansion, but plays minor or no role in remobilization of P in leaf tissues or in maintaining membrane integrity. The role of calcium (Ca2 ) in signaling environmental stress has been demonstrated; however, its role in signaling low phosphorus (P) stress and subsequent adaptive responses in trees are largely unexplored. The aim of this study was to examine the effects of Ca2 application on root growth and expansion, seedling growth, remobilization of P, and maintaining membrane integrity in leaf tissues. Thus, a sand culture experiment was set up with five Ca2 concentrations (0, 1, 3, 5, and 10 mmol/L Ca(NO3)2·4H2O) under two P treatments (0.0 and 1.0 mmol/L KH2PO4). After 4 months, growth attributes, P and Ca2 accumulations, and biochemical responses were determined. Results showed that (1) low P seedlings supplied with 5 mmol/L Ca2 produced longer roots, larger root surface area, higher root diameter, and larger root volume than the control; (2) seedling height and root collar diameter were positively affected by addition of 3 and 5 mmol/L Ca2 into the growing media, and whole plant biomass of low P seedlings supplied with 5 mmol/L Ca2 was significantly higher than the control; (3) whole plant P accumulation was higher in 3 and 5 mmol/L Ca2 treatments in low P seedlings, whereas whole plant Ca2 accumulation increased linearly with increasing Ca2 concentration; and (4) the effects of Ca2 on malondialdehyde and soluble protein contents and acid phosphatase activity did not show consistent trend with increasing or decreasing Ca2 concentration. In conclusion, Ca2 induces adaptive response to low P stress through increased root growth and expansion, but plays minor or no role in remobilization of P in leaf tissues or in maintaining membrane integrity.

PLANT biomass; PHOSPHORUS; ACID phosphatase; FIR; ROOT growth; CHINA fir; SURFACE area; SEEDLINGS

Trees: Structure & Function, 2020, Vol 34, Issue 3, p825

0931-1890

Academic Journal

10.1007/s00468-020-01961-4