Phenolic Acids Released in Maize Rhizosphere During Maize-Soybean Intercropping Inhibit Phytophthora Blight of Soybean

Abstract

Interspecies interactions play a key role in soil-borne disease suppression in intercropping systems. However, there are limited data on the underlying mechanisms of soil-borne Phytophthora disease suppression. Here, a field experiment confirmed the effects of maize and soybean intercropping on Phytophthora blight of soybean caused by Phytophthora sojae. Experimentally, the roots and root exudates of maize were found to attract P. sojae zoospores and inhibit their motility and the germination of cystospores. Furthermore, five phenolic acids (p-coumaric acid, cinnamic acid, p-hydroxybenzoic acid, vanillic acid, and ferulic acid) that were consistently identified in the root exudates and rhizosphere soil of maize were found to interfere with the infection behavior of P. sojae. Among them, cinnamic acid was associated with significant chemotaxis in zoospores, and p-coumaric acid and cinnamic acid showed strong antimicrobial activity against P. sojae. However, in the rhizosphere soil of soybean, only p-hydroxybenzoic acid, low concentrations of vanillic acid, and ferulic acid were identified. Importantly, the coexistence of five phenolic acids in the maize rhizosphere compared with three phenolic acids in the soybean rhizosphere showed strong synergistic antimicrobial activity against the infection behavior of P. sojae. In summary, the types and concentrations of phenolic acids in maize and soybean rhizosphere soils were found to be crucial factors for Phytophthora disease suppression in this intercropping system.

Impacts of crop residues on soil health: a review

“…The inhibition effect was 21.5-75.7% and 48.7-100% at the concentrations of 10 mM and 20 mM, respectively [60]. Meanwhile, PAs have been shown to have antifungal effects, inhibitory effects on reducing growth of weed species and aid in the formation and stabilization of aggregates under appropriate concentrations [61][62][63]. The research results of Hou et al showed that B. cinerea mycelial growth and spore generation decreased by 86.18% and 69.10%, respectively, following 0.2 g/L PAs treatment [64].…”

Phytophthora zoospores: From perception of environmental signals to inoculum formation on the host-root surface

“…They are involved in attracting or repulsing beneficial and pathogenic microorganisms ( Fig. 2 C) [57] , [58] , [59] . Investigations addressing how and which rhizospheric compounds direct zoospore chemotaxis toward roots have resulted in the identification of stimuli among root exudates.…”

Transcriptomic Responses of Rhizobium phaseoli to Root Exudates Reflect Its Capacity to Colonize Maize and Common Bean in an Intercropping System

“…Ferulic acid is an abundant phenolic acid attached to plant walls and its abundance in maize is at least ten times more than in other cereals (Bento-Silva et al, 2018). Ferulic acid is released by corn roots (Zhang et al, 2020). In bean, coumaric acid and 4-hydroxybenzoate may be preferentially used by Ch24-10 according to the level expression of pobA gene and pca operon.…”

“…Ch24-10 metabolic processes induced by milpa exudates are denoted by a red asterisk. The information used here was obtained from transcriptome data in the presence of beans (Supplementary Table 1), maize (Supplementary Table 2), and milpa (Supplementary Table 3) and from data about chemical composition of exudates reported in the literature (Bolaños-Vásquez and Werner, 1997; Carvalhais et al, 2011;Fan et al, 2012;Tawaraya et al, 2014;Zhang et al, 2020). flagellar motor, hook and basal complex, and for the biosynthesis of flagellin were found expressed in all transcriptomes.…”