Ascophyllum nodosum Extract and Mycorrhizal Colonization Synergistically Trigger Immune Responses in Pea Plants against Rhizoctonia Root Rot, and Enhance Plant Growth and Productivity

Abstract

Rhizoctonia root rot is one of the most destructive diseases affecting pea crops, resulting in up to 75% loss. In this study, the biocontrol activity of seaweed (Ascophyllum nodosum) extract at 1, 2, and 3% and/or mycorrhization of pea roots was investigated against Rhizoctonia root rot under greenhouse conditions. In addition, their effects on the transcriptional, physiological, ultrastructural, and growth status of pea plants were also studied. The results showed that the mycorrhizal colonization of pea roots and the application of the seaweed extract at 3% synergistically overexpressed the responsive factor (JERF3) recording 18.2-fold, and the defense-related genes peroxidase (23.2-fold) and chitinase II (31.8-fold). In addition, this treatment improved the activity of the antioxidant enzymes POD and PPO, increased the phenolic content in pea roots, and triggered multiple hypersensitivity reactions at the ultrastructural level of the cell, leading to a 73.1% reduction in disease severity. Moreover, a synergistic growth-promoting effect on pea plants was also observed. The photosynthetic pigments in pea leaves were enhanced in response to this dual treatment, which significantly improved their yield (24 g/plant). The inducing effect of mycorrhizal colonization on plant resistance and growth has been extensively studied. However, developing improved and synergistically acting biological agents for plant disease control and growth promotion as alternatives to the chemical fungicides is crucial for safety and food security. Based on these results, it can be concluded that the mycorrhizal colonization of pea roots and soaking their seeds in the A. nodosum extract at 3% have a promising and improved biocontrol activity against R. solani, and a growth-promoting effect on pea plants. However, field applications should be evaluated prior to any use recommendations.

Synergism between Streptomyces viridosporus HH1 and Rhizophagus irregularis Effectively Induces Defense Responses to Fusarium Wilt of Pea and Improves Plant Growth and Yield

“…One of the most important results reported in this study is the synergistic growth-promoting effect due to treating pea plants with S. viridosporus HH1 and colonization with R. irregularis . Mycorrhization of different plant species has been reported to improve their development and yield using multiple modes of action [ 23 , 57 ]. Enhancing water and nutrient acquisition from the soil is one of the most important benefits provided by the mycorrhizal fungi throughout their mutualistic relationship with the hosts.…”

“…Among the bioagents widely studied for their biocontrol activity against different plant diseases is the arbuscular mycorrhizal fungi (AMF) [ 7 , 21 , 22 , 23 ]. They are biotrophic fungi belonging to the subphylum Glomeromycotina, which colonizes the roots of around 80% of terrestrial plants, forming a mutualistic association [ 24 ].…”

Endophytic Bacillus subtilis SR22 Triggers Defense Responses in Tomato against Rhizoctonia Root Rot

“…Different anastomosis groups (AGs) of R. solani have been reported to infect tomato plants at varying degrees, including AG-2-1, AG-2-2, AG-3-PT, AG-4-HG-I, and AG-5 [ 8 ]. A variety of strategies have been used to manage this disease including chemical, physical, crop rotation, resistant cultivars, and biological control [ 9 , 10 , 11 ]. Among these alternative techniques, biological control is the most favorable, owing to its safety, eco-friendliness, and efficiency [ 12 ].…”

“…Among these alternative techniques, biological control is the most favorable, owing to its safety, eco-friendliness, and efficiency [ 12 ]. The biological control of R. solani on various crops has been extensively studied [ 10 , 11 , 13 ].…”

“…The priming of plant immunity results in the activation of multiple hypersensitivity reactions in the host, such as lignin deposition, accumulation of polyphenolic compounds and phytoalexins, and/or overexpression of multiple defense-related genes [ 23 ]. Among the up-regulated genes, advantageous entophyte colonization has shown to activate jasmonate and ethylene responsive factor 3 ( JERF3 ), which controls a group of defense-responsive genes via jasmonate/ethylene signaling pathways such as peroxidase gene ( POD ), which encodes the antioxidant peroxidase enzyme, and the antifungal pathogenesis-related protein 1 gene ( PR1 ) [ 10 , 24 ]. The objectives of this study were to (1) investigate the antagonistic activity of the endophytic B. subtilis against R. solani in vitro; (2) identify its produced antifungal secondary metabolites; (3) evaluate its bio-control activity against Rhizoctonia root rot of tomato under greenhouse conditions; (4) investigate its effects on the transcriptional level of the defense-related genes JERF3 , PR1 , and POD in tomato; (5) investigate its effect on the plant growth and biochemical parameters.…”