Systemic fungicidal activity of phenazine‐1‐carboxylic acid‐valine conjugate against tobacco sore shin and its translocation and accumulation in tobacco (Nicotiana tabacum L.)

Abstract

BACKGROUND: Tobacco sore shin caused by Rhizoctonia solani Kühn is a major soil-borne fungal disease of tobacco, gradually causing infected stems to become thin and dry, leading to great losses to Chinaʼs tobacco industry. Fungicides with phloem mobility are needed for application to foliage to effectively control root or vascular system pathogens. In this study, phenazine-1-carboxylic acid-valine conjugate (PCA-Val) with strong phloem mobility was tested for control of tobacco sore shin. In vitro fungicidal activity, systemicity, and in vivo efficacy of PCA-Val against R. solani in tobacco seedling were evaluated. RESULTS:In vitro fungicidal activity of PCA-L-Val against R. solani was lower than that of PCA or PCA-D-Val, but the in vivo protective activity and curative activity of PCA-L-Val was the highest among these chemicals tested. The systemicity tests in tobacco seedlings revealed that PCA did not possess phloem mobility, while PCA-L-Val and PCA-D-Val exhibited strong phloem mobility and could be transported and accumulated in the lower part of the seedling as well as throughout the phloem. In addition, we also found that, just like reported hormone amino acid conjugates, PCA-L-Val could be hydrolyzed by tobacco seedlings, to release free PCA. CONCLUSIONS: The current research results indicated that PCA-L-Val possess good phloem transport in tobacco and promising in vivo antifungal activity against R. solani, which can be used as a phloem-mobile fungicide against tobacco sore shin in production practice.

An Exploration of the Effect of the Kleier Model and Carrier-Mediated Theory to Design Phloem-Mobile Pesticides Based on Researching the N-Alkylated Derivatives of Phenazine-1-Carboxylic Acid-Glycine

“…Compounds 4a (CH 3 -N), 4b (C 2 H 5 -N), and 4c ( i -C 3 H 7 -N) had better phloem mobility, with the average concentrations in phloem sap of 14.62 μΜ, 13.98 μΜ, and 17.63 μΜ in the first 5h, which were 8 to 10 times higher than PCA-Gly (1.71 μΜ). Compared with our previous studies [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 ], compounds 4a – 4c ’s phloem transportation ability comprised the best class of compounds. The results imperfectly correspond to Carrier-mediated theory, as based on Carrier-mediated theory, PCA-Gly should have the best phloem mobility.…”

Uptake and transport of antibiotic kasugamycin in castor bean (Ricinus communis L.) seedlings

“…A series of monosaccharide-fipronil conjugates showed phloem mobility in castor bean ( Wu et al, 2019 ; Wang et al, 2022 ). Phenazine-1-carboxylic acid-valine conjugate possess good phloem transport in tobacco and promising in vivo antifungal activity against Rhizoctonia solani Kühn ( Zhu et al, 2022 ).…”

Cytochrome bc1 Complex: Potential Breach to Improve the Activity of Phenazines on Xanthomonas

“…Phenazines and their producers have been studied for over 1 century. − Today, the study of phenazines and their derivatives to improve their inhibitory effect on pathogens is still an exciting prospect worldwide. ,− At present, PCA has been mass-produced and registered for controlling a lot of fungal diseases in China . Xu reported the efficiency of using PCA to inhibit Xanthomonas spp., but some tolerance processes limited its use .…”