Biocontrol of Plant Diseases Using Glycyrrhiza glabra Leaf Extract.

The growing concern regarding the potential risks of pesticides and their impact on nontarget organisms stimulates the development and application of alternative, environmentally friendly products. It seems necessary to develop alternatives for conventional products and for those already widely used in organic agriculture, e.g., copper. Very importantly, such alternative products should not limit the productivity and profitability of agriculture. In this study, we examined the efficacy of licorice (Glycyrrhiza glabra) leaf extract as such an alternative. We tested its impact on the virulence of Pseudomonas syringae toward the model plant Arabidopsis thaliana and the crop plant tomato (Solanum lycopersicum) as well as of Clavibacter michiganensis, Xanthomonas campestris, and Phytophthora infestans toward tomato, at multiple levels. We demonstrate that licorice leaf extract acts as a direct fungicide and bactericide. Moreover, it acts against a metalaxyl-resistant P. infestans strain. In addition, the extract from licorice leaves influences the plant immune system, modulating the plant responses to the challenge with pathogen(s); this involves both salicylic acid and ethylene-based responses. Our results show that in addition to the well-known use of licorice root extract in medicine, the leaf extract can be an effective alternative in organic and integrated farming, contributing to copper reduction and resistance management.[Formula: see text] Copyright © 2022 The Author(s). This is an open-access article distributed under the CC BY 4.0 International license.

Formation of transfer cells and H(+)-ATPase expression in tomato roots under P and Fe deficiency.

In roots of tomato ( Lycopersicon esculentum Mill.), extranumerary root hairs and transfer cell-like wall ingrowth depositions in the rhizodermis were developed in response to P and Fe deficiency. Immunocytolocalization of the plasma membrane H(+)-ATPase in roots of P-deficient plants revealed no appreciable increase in H(+)-ATPase density relative to control plants. In transfer cells, immunogold labeling was considerably higher than in ordinary rhizodermal cells. H(+)-ATPase sites were asymmetrically distributed in cells with and without wall ingrowths under P-deficient conditions. A split-root study revealed that the frequency of transfer cells was higher in the low-P half of the root system, but the density of H(+)-ATPase molecules was enhanced only in the high-P half of the split roots, suggesting that formation of transfer cells was controlled directly by the external Pi concentration, whereas ATPase expression was regulated indirectly by the internal nutrient status of the plant. The role of hormones in the induction of transfer cells was investigated by treating plants with the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) or various ethylene antagonists. Transfer cells were induced by ACC to an extent similar to that observed after P or Fe starvation, but inhibitors of either ethylene synthesis or action did not decrease their frequency. These results suggest that ethylene was not required for the induction of transfer cells but changes in ethylene levels appeared to modulate the number of cells forming wall ingrowths. In roots of ethylene-insensitive Never-ripe tomato plants the frequency of transfer cells was rather increased than decreased under most growth conditions relative to the wild type, indicating that ethylene responsiveness played no critical role in the differentiation of transfer cells and that the transduction of signals ultimately leading to their formation was independent of the ethylene signaling cascade.