Induction of phytoalexins and proteins related to pathogenesis in plants treated with extracts of cutaneous secretions of southern Amazonian Bufonidae amphibians

Abstract

Cutaneous secretions produced by amphibians of the family Bufonidae are rich sources of bioactive compounds that can be useful as new chemical templates for agrochemicals. In crop protection, the use of elicitors to induce responses offers the prospect of durable, broad-spectrum disease control using the plant’s own resistance. Therefore, we evaluated the potential of methanolic extracts of cutaneous secretions of two species of amphibians of the family Bufonidae found in the Amazon biome—Rhaebo guttatus (species 1) and Rhinella marina (species 2)—in the synthesis of phytoalexins in soybean cotyledons, bean hypocotyls, and sorghum mesocotyls. Additionally, changes in the enzyme activity of β-1,3-glucanase, peroxidase (POX), and polyphenol oxidase (PPO) and in the total protein content of soybean cotyledons were determined. In the soybean cultivar ‘TMG 132 RR’, our results indicated that the methanolic extract of R. guttatus cutaneous secretions suppressed glyceollin synthesis and β-1,3-glucanase activity and increased POX and PPO activities at higher concentrations and total protein content at a concentration of 0.2 mg/mL. On the other hand, the methanolic extract of R. marina cutaneous secretions induced glyceollin synthesis in the soybean cultivars ‘TMG 132 RR’ and ‘Monsoy 8372 IPRO’ at 0.1–0.2 mg/mL and 0.2 mg/mL, respectively. The methanolic extract of R. marina cutaneous secretions also increased the specific activity of POX and PPO in ‘Monsoy 8372 IPRO’ and ‘TMG 132 RR’, respectively, and decreased the activity of β-1,3-glucanases in ‘Monsoy 8372 IPRO’. At 0.3 mg/mL, it stimulated phaseolin synthesis. The extracts did not express bioactivity in the synthesis of deoxyanthocyanidins in sorghum mesocotyls. The study in soybean suggests that the bioactivity in defense responses is influenced by cultivar genotypes. Therefore, these results provide evidence that extracts of cutaneous secretions of these amphibians species may contribute to the bioactivity of defense metabolites in plants.

Transcriptomic changes in green bean pods against grey mould and white rot diseases via field application of chemical elicitor nanoparticles

“…While Diego et al [37] observed that the response to phytoalexin accumulation in different varieties elicited by salicylic acid was found to be dose‐response of elicitor treatments as well as variety responsive. Raasch‐Fernandes et al [38] reported that methanolic extract of Rhinella marina cutaneous secretions stimulated phaseolin synthesis in bean hypocotyls.…”

In vitro antimicrobial activity of methanolic extracts from cutaneous secretions of Amazonian amphibians against phytopathogens of agricultural interest

“…To test the effect of the extracts on F. udum, F. solani, C. truncatum, A. flavus, R. solani, and M. phaseolina, we used concentrations of 0.1, 0.2, 0.3, 0.4, and 0.5 mg mL -¹ of the methanolic extracts of R. guttatus VOL. 51(2) 2021: 145 -155 ACTA AMAZONICA and R. marina cutaneous secretions (Raasch-Fernandes et al 2019), sterile water as negative control, and a fungicide mixture of metconazole (80 mg mL -1 ) + pyraclostrobin (130 mg mL -1 ) (Opera Ultra EC; BASF Corporation) as positive control. To test the effect on C. pseudometrosideri, we used the same extract concentrations and negative control, and azoxystrobin (200 mg mL -1 ) + cyproconazole (80 mg mL -1 ) (Priori Xtra; Syngenta Crop Protection AG) as positive control.…”

“…Bufadienolides are an important group of steroid hormones with physiological and defense functions (Perera Córdova et al 2016) that have vasoconstriction (Kamboj et al 2013), antiviral (Sousa et al 2017), antitumor (Yuan et al 2016), cytotoxic (Ferreira et al 2013;Li et al 2015), antibacterial and antifungal properties (Rodríguez et al 2017). Therefore, bufadienolides have potential for use to minimize damage and losses resulting from diseases caused by plant pathogenic fungi (Raasch- Fernandes et al 2019).…”

Eruca sativa seed napin structural insights and thorough functional characterization

“…bacteria, fungi and insects. As a result plants can produce a large variety of antimicrobial compounds such as phytoalexins and proteins 1 , 2 . In particular, plants protect themselves by secretion of small antimicrobial or antifungal proteins such as lipid transfer proteins 3 , snakins 4 , plant defensins 5 , hevein-like peptides 6 , glycine-rich peptides and napins 7 .…”