Cinnamic Acid Toxicity on the Structural Resistance and Photosynthetic Physiology of Faba Bean Promoted the Occurrence of Fusarium Wilt of Faba Bean, Which Was Alleviated Through Wheat and Faba Bean Intercropping

Intercropping improves faba bean photosynthesis and reduces disease caused by Fusarium commune and cinnamic acid-induced stress

Modern intensive cropping systems often contribute to the accumulation of phenolic acids in the soil, which promotes the development of soilborne diseases. This can be suppressed by intercropping. This study analyzed the effects of intercropping on Fusarium wilt based on its effect on photosynthesis under stress by the combination of Fusarium commune and cinnamic acid. The control was not inoculated with F. commune, while the faba bean plants (Vicia faba L.) were inoculated with this pathogen in the other treatments. The infected plants were also treated with cinnamic acid. This study examined the development of Fusarium wilt together with its effects on the leaves, absorption of nutrients, chlorophyll fluorescence parameters, contents of photosynthetic pigments, activities of photosynthetic enzymes, gas exchange parameters, and the photosynthetic assimilates of faba bean from monocropping and intercropping systems. Under monocropping conditions, the leaves of the plants inoculated with F. commune grew significantly less, and there was enhanced occurrence of the Fusarium wilt compared with the control. Compared with the plants solely inoculated with F. commune, the exogenous addition of cinnamic acid to the infected plants significantly further reduced the growth of faba bean leaves and increased the occurrence of Fusarium wilt. A comparison of the combination of F. commune and cinnamic acid in intercropped wheat and faba bean compared with monocropping showed that intercropping improved the absorption of nutrients, increased photosynthetic pigments and its contents, electron transport, photosynthetic enzymes, and photosynthetic assimilates. The combination of these factors reduced the occurrence of Fusarium wilt in faba bean and increased the growth of its leaves. These results showed that intercropping improved the photosynthesis, which promoted the growth of faba bean, thus, reducing the development of Fusarium wilt following the stress of infection by F. commune and cinnamic acid. This research should provide more information to enhance sustainable agriculture.

Promotion of faba bean seedling growth under Fusarium oxysporum f. sp. fabae and cinnamic acid stress in faba bean-wheat intercropping system and underlying proteomic mechanisms

Continuous cropping severely affects faba bean growth, mainly due to pathogen and autotoxic substance accumulation. Here, we used faba bean monocropping (M) and intercropping with wheat (I), with stress treatments of Fusarium oxysporum f. sp. fabae (FOF) alone (F) and combined with cinnamic acid (F + C), to analyze seedling growth, defense-related enzymes, levels of resistance-associated substances, and protein expression profiles in roots. The results showed that intercropping mitigated the inhibitory effects of FOF and cinnamic acid. FOF resulted in increased activities of defense-related enzymes as well as levels of resistance-associated substances. Proteomic analysis showed that 22 proteins were upregulated following FOF inoculation (M + F), and 6 proteins were downregulated after the addition of cinnamic acid (M + F + C) in monocropping plants; these proteins were mainly involved in pathways associated with carbohydrate metabolism, energy, and the cytoplasm. Comparison of monocropping and intercropping indicated that the upregulated proteins were mostly associated with stress and defense, carbohydrate transport and metabolism, maintenance of cellular homeostasis, and protein synthesis. KEGG analysis revealed that intercropping increased enrichment in pathways associated with metabolism, ribosomes, biosynthesis of secondary metabolites, proteasomes, pyruvate metabolism, and pentose and glucuronate interconversions. The results indicated that intercropping mitigated growth inhibition by FOF and cinnamic acid by increasing energy production, maintaining normal cellular functions, and promoting the synthesis of defense-associated secondary metabolites. These findings provide a basis for further investigation into the molecular mechanisms underlying the effects of intercropping in controlling resistance to Fusarium wilt in the faba bean.