Streptomyces rimosus rhizobacteria and Glomus mosseae mycorrhizal fungus inoculation alleviate salinity stress in grapevine through morphophysiological changes and nutritional balance

Abstract

Arbuscular mycorrhizal fungi (AMF) and plant growth-promoting rhizobacteria (PGPR) have positive impacts on growth and production of plants under saline condition. However, their interactive effects on plant behavior under salt stress remained unclear. To address this, a glasshouse experiment was conducted to elucidate the effect of the single and combined (co-inoculation) application of Glomus mosseae (Gm) AMF and Streptomyces rimosus (Sr) PGPR on salt tolerance of Sultana grapevine (Vitis vinifera L.). Based on results, the combined inoculation with Gm AMF and Sr PGPR markedly improved shoot and root morphometric traits and also soluble carbohydrate, soluble proteins, proline content compared to those vines inoculated with these symbionts alone or uninoculated vines under saline condition. The highest main root length was related to inoculated vines with Sr PGPR, which was 18.5% higher than uninoculated control plants under saline condition. Under saline condition, co-inoculation with Gm AMF and Sr PGPR decreased leaf necrotic, leaf ion leakage and malondialdehyde content by 31%, 43% and 38% but increased SPAD index, relative water content, catalase and guaiacol peroxidase activity by 45%, 26%, 30% and 53% compared with control uninoculated plant. Among salt stressed plants, the single inoculated vines with Gm AMF showed the highest total phenol and flavonoid content compared to control plants. In vines grown under saline condition, the highest content of leaf P, Mg, Fe, Zn and Mn were related to Gm plus Sr -inoculated vines. Leaf NO−3 and K of all inoculated vines did not showed statistically significant difference with each other's. Under saline condition, root NO3, K, Mg, Fe, Zn and Mn did not showed significant difference among inoculated plants but differed significantly with control vines. Therefore, combined application of Gm AMF and Sr PGPR assisted host plants to uptake higher nutrients during salt stress; confer salt tolerance to vines by increase in osmoregulants, phenolic compounds and antioxidant enzymes activities in their tissues.