Effect of NaCl on growth and ion relations in two salt-tolerant strains of Paxillus involutus

Abstract

The effect of NaCl on growth, biomass and ion relations of two salt-tolerant isolates of Paxillus involutus, MAJ and NAU were investigated. The two Paxillus strains were exposed to the following concentrations of NaCl: 0, 100, 200 and 500 mmol·L -1 . Growth of MAJ and NAU was enhanced by 100 mmol·L -1 NaCl but severely inhibited at the concentration of 500 mmol·L -1 . NAU exhibited a greater capacity to exclude Na + and Cl -under all salinity levels, whereas the salt-includer MAJ had a higher capacity in nutrient uptake under salt stress. The ratios Na + /K + , Na + /Ca 2+ and Na + /Mg 2+ in NaCl-treated MAJ and NAU did not increase at levels of 100 and 200 mmol·L -1 NaCl but markedly increased at 500 mmol·L -1 . This suggests that the two strains, especially MAJ, enhanced nutrient uptake corresponding to the increased Na + influx at moderate salinity. We conclude that both MAJ and NAU are able to tolerate 500 mmol·L -1 NaCl but there are species-specific differences in retaining ionic homeostasis in the two Paxillus strains. NAU is a salt-excluder, MAJ is a salt-includer but retains a high capacity in nutrient selectivity under saline conditions. Their definite mechanisms to enhance salt tolerance of mycorrhizal hosts need further study.

Variations in biomass of fungal guilds are primarily driven by factors related to soil conditions in Mediterranean Pinus pinaster forests

“…Mycorrhizal symbiosis has been proposed as a key factor for better salt tolerance of woody species by reducing Na uptake (Guerrero-Galán et al 2019). While high salinity imposes Na toxicity and reduces fungal growth, mild-moderate Na occurrence has been reported to stimulate the growth of some mycorrhizal species (Bois et al 2006;Matsuda et al 2006;Zhang et al 2008), which may contribute to the positive correlations between soil Na and mycorrhizal biomass. However, the mechanisms driving mycorrhizal biomass responses to salinity variation are not known, and the effects of salinity on mycorrhizal-related processes need further investigation.…”

Paxillus involutus Strains MAJ and NAU Mediate K+/Na+ Homeostasis in Ectomycorrhizal Populus × canescens under Sodium Chloride Stress

“…[See online article for color version of this figure. ] in the maintenance of K + homeostasis by delivering the nutrient to the plant and slowing the loss of K + under NaCl stress. Zhang et al (2008) reported that P. involutus mycelium, especially strain MAJ, increased the uptake of K + after exposure to salt treatment. Salt shock caused an instantaneous influx of K + into the fungal mycelium; however, ST-and LT-stressed hyphae exhibited a K + efflux (Fig.…”

“…Paxillus involutus strains MAJ and NAU have been identified as highly salt-tolerant fungi (Gafur et al, 2004;Langenfeld-Heyser et al, 2007;Zhang et al, 2008). Colonization with P. involutus strain MAJ reduces the buildup of Na + but enhances K + accumulation in the leaves of a salt-sensitive hybrid poplar, Populus 3 canescens (Langenfeld-Heyser et al, 2007, Luo et al, 2011.…”

Ectomycorrhizal symbiosis helps plants to challenge salt stress conditions

“…or Laccaria sp. (Hutchison 1990;Kernaghan et al 2002), and of isolates of the same species as Paxillus involutus (Zhang et al 2008), Suillus spp. (Hutchison 1990;Dixon et al 1993;Bois et al 2006a;Tang et al 2009;Obase et al 2010), and Pisolithus sp.…”

“…In all cases, ion toxicity seems to be responsible for most of the negative effects observed on fungal growth, compared to the osmotic component due to the abundance of solutes in the environment (Dixon et al 1993;Chen et al 2001;Kernaghan et al 2002;Bois et al 2006a). Also, some ectomycorrhizal fungi seem to have evolved towards salt tolerance and their growth can even be stimulated by the application of moderate NaCl concentrations in the range of 25-50 mM (Dixon 1993;Bois et al 2006a;Matsuda et al 2006) or higher (Zhang et al 2008;Obase et al 2010). Recent studies using genomic techniques, have detected how populations of the ectomycorrhizal fungus Suillus brevipes in North America are able to adapt to stress associated with climate regimes and abiotic environments (Branco et al 2015(Branco et al , 2017.…”