The efficiency of arbuscular mycorrhiza for improving tolerance of Valeriana officinalis L. and enhancing valerenic acid accumulation under salinity stress

(V)alerian (Valeriana officinalis L.), which is considered as a medicinal plant, is commonly used in traditional medicine. This study aimed to evaluate the effect of arbuscular mycorrhizal (AM) fungi association under moderate and high salinity stress on growth and physio-biochemical traits of V. officinalis. The bio-ameliorative efficiency of two AM species, Rhizophagus intraradices and Funneliformis mosseae was also compared. The mycorrhizal inoculation generally increased the salt tolerance of plant and positively affected plant growth, P, K+, Mg2+ concentration and the ratios of total chlorophyll: carotenoids, K+: Na+, Ca2+: Na+, and Mg2+: Na+ in shoots compared with those of the non-mycorrhizal plants under saline condition. Moreover, the presence of AM symbiosis mitigated the salinity-induced increase in shoot Na+ concentration, shoot proline, and oxidative damage to membranes. AM fungi considerably promoted root proline and total soluble sugars and total phenolics in shoots and roots versus non-mycorrhizal V. officinalis. Moderate salinity stress increased valerenic acid production, which was more pronounced in F. mosseae inoculated plants. The outcome of the symbiosis was associated with the AM species used, and F. mosseae was more efficient than R. intraradices in the alleviation of salinity stress. This study suggests the potential use of mycorrhizal technology as a practical biotechnological approach to enhance growth and augment bioactive compounds production of V. officinalis in salt-affected soils.