Mycorrhizal fungal colonization promotes apparent growth and physiology of Alhagi sparsifolia seedlings under salt or drought stress at vulnerable developmental stage

Abstract

Alhagi sparsifolia is a dominant species in the lower Tarim River desert ecosystem and an important mycorrhizal symbiont. However, it is unclear how its seedlings cope with salt and drought stresses and develop effective survival strategies with the assistance of arbuscular mycorrhizal fungi (AMF) during the vulnerable growth stage. Therefore, in this study, we investigated the effects of salt or drought stress on the growth rate; nutrient uptake; photosynthesis; and the levels of antioxidant enzymes, osmoregulatory substances, and hormones in A. sparsifolia seedlings. We included following six groups: control/CK-NM (without salt or drought stress and no AMF inoculation), D-NM (drought stress and no AMF inoculation), S-NM (salt stress and no AMF inoculation), CK-AM (AMF inoculation and no salt or drought stress), D-AM (drought stress and AMF inoculation), and S-AM (salt stress and AMF inoculation). The results revealed that AMF inoculation promoted seedling growth, particularly root growth and phosphorus nutrient uptake, in A. sparsifolia. Salt and drought stresses negatively affected the growth, photosynthetic capacity, and nutrient accumulation in the above- and below-ground parts of the seedlings and stimulated the antioxidant defense system and accumulation of osmoregulatory substances in them. AMF inoculation under salt and drought stresses could alleviate toxic symptoms in A. sparsifolia by promoting root growth, enhancing nutrient uptake, activating antioxidant enzyme activity, and regulating hormonal levels. These effects of AMF were mainly reflected in root growth under drought stress and antioxidant enzyme activity under salt stress. The beneficial effect of AMF under salt stress was better than that under drought stress. This study demonstrated that AMF plays a significant role in assisting A. sparsifolia seedlings to quickly pass through the vulnerable growth stage under salt and drought stresses. Therefore, A. sparsifolia seedlings with AMF have potential application in restoration of desert ecosystem.

Arbuscular Mycorrhizal Fungi and Higher Plants

“…AM fungus G. fasciculatum, inoculation induces drastic changes in growth parameters and in the activity of antioxidants in cyclamen, infected with C. gloeosporioides (Maya and Matsubara 2013). A similar study conducted by Chen et al (2023b) reported an increase in the activity of antioxidants {(SOD, catalase (CAT) and peroxidase (POD)} in tea plants inoculated with AM fungi R. intraradices BGC JX04B. Tea plants inoculated with AM fungi significantly reduce the anthracnose disease severity caused by Colletotrichum camelliae.…”

“…Further, the association of G. viscosum also increased the concentration of glutathione (GSH) and ascorbate (ASC) in artichoke plants, while a reduction in hydrogen peroxidase (H 2 O 2 ) and lipid peroxidation levels was observed (Villani et al 2021). Deciphering the effect of AMF on tea anthracnose incidences unraveled that mycorrhizal inoculation significantly increases the content of CAT, POD, and superoxide ions in tea plants and inhibited the proliferation of C. camelliae, thus protecting the tea plants from damages caused by anthracnose disease (Chen et al 2023b). AMF-induced changes in plant metabolic profile directly or indirectly influence plant tolerance to any pathogenic fungal challenges.…”