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Snow pea root rot in China is caused by Fusarium solani (FSH) and Fusarium avenaceum (FAH), which affect snow pea production. The chemical control methods used against FSH and FAH are toxic to the environment and resistance may be developed in persistence applications. Therefore, an alternative approach is needed to control these pathogens. This study focuses on Trichoderma longibrachiatum strains (TL6 and TL13), mycoparasitic mechanisms of FSH and FAH, as well as growth-promoting potentials on snow pea seedlings under FSH and FAH stress at the physiological, biochemical, and molecular levels. The average inhibitory rates of TL6 against FSH and FAH were 54.58% and 69.16%, respectively, on day 7. Similarly, TL13 average inhibitory rates against FSH and FAH were 59.06% and 71.27%, respectively, on day 7. The combined TL13 and TL6 with FSH and FAH reduced disease severity by 86.6, 81.6, 57.60, and 60.90%, respectively, in comparison to the controls. The snow pea plants inoculated with FSH and FAH without TL6 and TL13 increased malondialdehyde (MDA) and hydrogen peroxide (H2O2) contents in the leaves by 64.8, 66.0, 64.4 and 65.9%, respectively, compared to the control. However, the combined FSH and FAH with TL6 and TL13 decreased the MDA and H2O2 content by 75.6, 76.8, 70.0, and 76.4%, respectively, in comparison to the controls. In addition, the combined TL6 + FSH and TL6 + FAH increased the activity of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) by 60.5, 64.7, and 60.3%, respectively, and 60.0, 64.9, and 56.6%, respectively, compared to the controls. Again, compared to the controls, the combined TL13 + FSH and TL13 + FAH increased the activity of SOD, POD, and CAT by 69.7, 68.6, and 65.6%, respectively, and 70.10, 69.5, and 65.8%, respectively. Our results suggest that the pretreatment of snow pea seeds with TL6 and TL13 increases snow pea seedling growth, controls FSH and FAH root rot, increases antioxidant enzyme activity, and activates plant defense mechanisms. The TL13 strain had the greatest performance in terms of pathogen inhibition and snow pea growth promotion compared to the TL6 strain.

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Root-knot nematodes are among the most significant pathogenic organisms due to their global distribution, capacity for destruction, and economic importance. Antagonistic bioagents are more effective alternative to synthetic pesticides in the suppression of root-knot nematodes. Bioagents reduce the use of synthetic chemicals, which are hazardous to both humans and the environment. Despite this, some bioagents, such as fungi and bacteria have unknown mechanisms. This review discusses the nematophagous bacteria and fungi that have been discovered so far, including Pochonia, Trichoderma sp., Pseudomonas sp., and Bacillus sp., with an overview of the current advances in research regarding their molecular and biochemical control mechanisms. Biological control agents (BCAs), as valuable ecological enemies of nematode infestations, use a range of mechanisms, such as parasitism, nutrient competition, toxin production, induce systemic resistance to antibiotics, enzymes, and enhance plant health. They suppress nematodes directly, improve plant growth, and facilitate the colonization and activities of antagonistic microbes in the rhizosphere. Understanding the molecular basis of BCAs suppression mechanisms provides the basis for their future incorporation into phytopathogen or plant disease control management. This study reviews the current threat posed by the root-knot nematode, biological control, antagonistic bioagents, and their mechanisms, and the future perspectives in modern agricultural sustainability to provide basis for the broad control of root-knot nematodes.

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