Exogenous genistein enhances soybean resistance to Xanthomonas axonopodis pv. glycines

Abstract

BACKGROUND Xanthomonas axonopodis pv. glycines (Xag) is the causal agent of bacterial pustule disease and results in enormous losses in soybean production. Although isoflavones are known to be involved in soybean resistance against pathogen infection, the effects of exogenous isoflavones on soybean plants remain unexplored. RESULTS Irrigation of soybean plants with isoflavone genistein inhibited plant growth for short periods, probably by inhibiting the tyrosine (brassinosteroids) kinase pathway, and increased disease resistance against Xag. The number of lesions was reduced by 59%–63% when applying 50 μg ml−1 genistein. The effects on disease resistance were observed for 15 days after treatment. Genistein also enhanced the disease resistance of soybean against the fungal pathogen Sclerotinia sclerotiorum. Exogenous genistein increased antioxidant capacity, decreased H2O2 level and promoted the accumulation of phenolics in Xag‐infected soybean leaves. Exogenous genistein reduced the amounts of endogenous daidzein, genistein and glycitein and increased the concentration of genistin, which was found to show strong antibacterial activity against the pathogen and to reduce the expression of virulence factor yapH, and flagella formation gene flgK. The expression of several soybean defense genes, such as chalcone isomerase, glutathione S‐transferase and 1‐aminocyclopropane‐1‐carboxylate oxidase 1, was upregulated after genistein treatment. CONCLUSIONS The effects of exogenous genistein on soybean plants were examined for the first time, revealing new insights into the roles of isoflavones in soybean defense and demonstrating that irrigation with genistein can be a suitable method to induce disease resistance in soybean plants. © 2022 Society of Chemical Industry.

p‐Aminobenzoic acid inhibits the growth of soybean pathogen Xanthomonas axonopodis pv. glycines by altering outer membrane integrity

“…The antibacterial activity of pABA against Xag was similar to that of other reported compounds. For example, isoflavone genistin showed a 1 mg mL −1 Minimum inhibitory concentration (MIC) towards Xag , which is similar to the MIC value obtained for pABA (1.37 mg mL −1 ) 27 . In contrast, biochanin A could completely inhibit Xag at <0.1 mg mL −1 , showing higher antibacterial activity against the pathogen than pABA 28 .…”

“…This concentration seems appropriate for use in fields. Chloromycetin was used in the experiments as a positive control given that this compound has been previously screened for the management of bacterial pustule disease in soybean 32 and its antibacterial properties have been compared to those of natural compounds biochanin A and genistein 27,28 . Although copper‐based bactericides, such as copper oxychloride, copper hydroxide or copper sulfate, have been thoroughly used for the control of Xag in soybean, 62 these kinds of compounds have had relevant negative effects on the environment and human health, 63 which is an important drawback.…”

“…Gram‐negative plant bacterial pathogens Acidovorax citrulli DSM17060, Dickeya dadanti 3937, Erwinia amylovora ATCC15580, Pseudomonas syringae pv. glycinea PG4180, Ralstonia solanacearum GMI1000, Xag NEAU001, 27 and Xanthomonas oryzae pv. oryzae PXO99 were used in the experiments.…”

Dipicolinic acid enhances kiwifruit resistance to Botrytis cinerea by promoting phenolics accumulation

“…To analyze the phenolic composition, the kiwifruit extracts obtained 3 days after treatment were injected into an HPLC instrument (Agilent 1200 series, Hewlett–Packard, USA) equipped with a C‐18 column (250 × 3.0 mm, Phenomenex, USA) at 35 °C and 254 nm 32 . The mobile phase was established as follows: 0–60% CH 3 CN in H 2 O from 0 to 60 min, 90% CH 3 CN in H 2 O from 60 to 70 min and 0% CH 3 CN in H 2 O from 70 to 80 min, with a flow rate of 1 mL min −1 and 5 μL of injection volume.…”

“…After collection of the peaks from 2 mL of kiwifruit extract by analytical‐scale HPLC, 32 the collected peaks were evaporated using a freeze‐drier and re‐dissolved in 100 μL of water. B. cinerea was located in the center of the Petri dish containing PDA medium.…”