SummaryPochonia chlamydosporia has been intensively studied in nematode control of different crops. We have investigated the interaction between P. chlamydosporia and the model system Arabidopsis thaliana under laboratory conditions in the absence of nematodes.This study demonstrates that P. chlamydosporia colonizes A. thaliana. Root colonization monitored with green fluorescent protein-tagged P. chlamydosporia and quantitative PCR (qPCR) quantitation methods revealed root cell invasion. Fungal inoculation reduced flowering time and stimulated plant growth, as determined by total FW increase, faster development of inflorescences and siliques, and a higher yield in terms of seed production per plant.Precocious flowering was associated with significant expression changes in key floweringtime genes. In addition, we also provided molecular and genetic evidence that point towards jasmonate signaling as an important factor to modulate progression of plant colonization by the fungus.Our results indicate that P. chlamydosporia provides benefits to the plant in addition to its nematophagous activity. This report highlights the potential of P. chlamydosporia to improve yield in economically important crops.
Summary Pochonia chlamydosporia is a soil fungus with a multitrophic lifestyle combining endophytic and saprophytic behaviors, in addition to a nematophagous activity directed against eggs of root‐knot and other plant parasitic nematodes. The carbohydrate‐active enzymes encoded by the genome of P. chlamydosporia suggest that the endophytic and saprophytic lifestyles make use of a plant cell wall polysaccharide degradation machinery that can target cellulose, xylan and, to a lesser extent, pectin. This enzymatic machinery is completed by a chitin breakdown system that involves not only chitinases, but also chitin deacetylases and a large number of chitosanases. P. chlamydosporia can degrade and grow on chitin and is particularly efficient on chitosan. The relevance of chitosan breakdown during nematode egg infection is supported by the immunolocalization of chitosan in Meloidogyne javanica eggs infected by P. chlamydosporia and by the fact that the fungus expresses chitosanase and chitin deacetylase genes during egg infection. This suggests that these enzymes are important for the nematophagous activity of the fungus and they are targets for improving the capabilities of P. chlamydosporia as a biocontrol agent in agriculture.
The fungal parasite of nematode eggs Pochonia chlamydosporia is also a root endophyte known to promote growth of some plants. In this study, we analysed the effect of nine P. chlamydosporia isolates from worldwide origin on tomato growth. Experiments were performed at different scales (Petri dish, growth chamber and greenhouse conditions) and developmental stages (seedlings, plantlets and plants). Seven P. chlamydosporia isolates significantly (P < 0.05) increased the number of secondary roots and six of those increased total weight of tomato seedlings. Six P. chlamydosporia isolates also increased root weight of tomato plantlets. Root colonisation varied between different isolates of this fungus. Again P. chlamydosporia significantly increased root growth of tomato plants under greenhouse conditions and reduced flowering and fruiting times (up to 5 and 12 days, respectively) versus uninoculated tomato plants. P. chlamydosporia increased mature fruit weight in tomato plants. The basis of the mechanisms for growth, flowering and yield promotion in tomato by the fungus are unknown. However, we found that P. chlamydosporia can produce Indole-3-acetic acid and solubilise mineral phosphate. These results suggest that plant hormones or nutrient ability could play an important role. Our results put forward the agronomic importance of P. chlamydosporia as biocontrol agent of plant parasitic nematodes with tomato growth promoting capabilities.
Chitin deacetylases (CDAs) act on chitin polymers and low molecular weight oligomers producing chitosans and chitosan oligosaccharides. Structurally-defined, partially deacetylated chitooligosaccharides produced by enzymatic methods are of current interest as bioactive molecules for a variety of applications. Among Pochonia chlamydosporia (Pc) annotated CDAs, gene pc_2566 was predicted to encode for an extracellular CE4 deacetylase with two CBM18 chitin binding modules. Chitosan formation during nematode egg infection by this nematophagous fungus suggests a role for their CDAs in pathogenicity. The P. chlamydosporia CDA catalytic domain (PcCDA) was expressed in E. coli BL21, recovered from inclusion bodies, and purified by affinity chromatography. It displays deacetylase activity on chitooligosaccharides with a degree of polymerization (DP) larger than 3, generating mono- and di-deacetylated products with a pattern different from those of closely related fungal CDAs. This is the first report of a CDA from a nematophagous fungus. On a DP5 substrate, PcCDA gave a single mono-deacetylated product in the penultimate position from the non-reducing end (ADAAA) which was then transformed into a di-deacetylated product (ADDAA). This novel deacetylation pattern expands our toolbox of specific CDAs for biotechnological applications, and will provide further insights into the determinants of substrate specificity in this family of enzymes.
Chitosan antifungal activity has been reported for both filamentous fungi and yeast. Previous studies have shown fungal plasma membrane as main chitosan target. However, the role of the fungal cell wall (CW) in their response to chitosan is unknown. We show that cell wall regeneration in Neurospora crassa (chitosan sensitive) protoplasts protects them from chitosan damage. Caspofungin, a β-1,3-glucan synthase inhibitor, showed a synergistic antifungal effect with chitosan for N. crassa but not for Pochonia chlamydosporia, a biocontrol fungus resistant to chitosan. Chitosan significantly repressed N. crassa genes involved in β-1,3-glucan synthesis (fks) and elongation (gel-1) but the chitin synthase gene (chs-1) did not present changes in its expression. N. crassa cell wall deletion strains related to β-1,3-glucan elongation (Δgel-1 and Δgel-2) were more sensitive to chitosan than wild type (wt). On the contrary, chitin synthase deletion strain (Δchs-1) showed the same sensitivity to chitosan than wt. The mycelium of P. chlamydosporia showed a higher (ca. twofold) β-1,3-glucan/chitin ratio than that of N. crassa. Taken together, our results indicate that cell wall composition plays an important role on -sensitivity of filamentous fungi to chitosan.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.