A thaumatin-like protein of Ocimum basilicum confers tolerance to fungal pathogen and abiotic stress in transgenic Arabidopsis

Abstract

Plant often responds to fungal pathogens by expressing a group of proteins known as pathogenesis-related proteins (PRs). The expression of PR is mediated through pathogen-induced signal-transduction pathways that are fine-tuned by phytohormones such as methyl jasmonate (MeJA). Here, we report functional characterization of an Ocimum basilicum PR5 family member (ObTLP1) that was identified from a MeJA-responsive expression sequence tag collection. ObTLP1 encodes a 226 amino acid polypeptide that showed sequence and structural similarities with a sweet-tasting protein thaumatin of Thaumatococcus danielli and also with a stress-responsive protein osmotin of Nicotiana tabacum. The expression of ObTLP1 in O. basilicum was found to be organ-preferential under unstressed condition, and responsive to biotic and abiotic stresses, and multiple phytohormone elicitations. Bacterially-expressed recombinant ObTLP1 inhibited mycelial growth of the phytopathogenic fungi, Scleretonia sclerotiorum and Botrytis cinerea; thereby, suggesting its antifungal activity. Ectopic expression of ObTLP1 in Arabidopsis led to enhanced tolerance to S. sclerotiorum and B. cinerea infections, and also to dehydration and salt stress. Moreover, induced expression of the defense marker genes suggested up-regulation of the defense-response pathways in ObTLP1-expressing Arabidopsis upon fungal challenge. Thus, ObTLP1 might be useful for providing tolerance to the fungal pathogens and abiotic stresses in crops.

Two CYP716A subfamily cytochrome P450 monooxygenases of sweet basil play similar but nonredundant roles in ursane‐ and oleanane‐type pentacyclic triterpene biosynthesis

“…RNA was quantified using a NanoDrop (Thermo Scientific) and first strand complementary DNA (cDNA) synthesis was carried out using MultiScribe reverse transcriptase (Applied Biosystems–Thermo Fisher Scientific, Waltham, MA, USA). Semi‐quantitative (sq) and quantitative (q) reverse transcription‐polymerase chain reaction (RT‐PCR) reactions were performed as described previously (Misra et al ., ). Relative transcript expression was determined following the 2 −ΔΔct method using ObACT as endogenous control.…”

Metabolic response induced by parasitic plant-fungus interactions hinder amino sugar and nucleotide sugar metabolism in the host

“…Basic symptoms, from initial fungal contact to the establishment of a stable relationship with the host, have been reported1. In the wake of such visual assessments, many studies are now addressing gene expression and functional enzymatic reactions related to nutrient exchange as well as the mechanisms of interaction234. In particular, many studies focus on chemical or biological causal agents released from the invading organism because these molecules initiate plant-fungus interactions.…”

Redox-dependent interaction between thaumatin-like protein and β-glucan influences malting quality of barley

“…During evolution, TLPs have assumed wide functional diversification, possibly because of their interaction with numerous ligands, such as actin, ice crystals, fungal proteins, and antifreeze proteins. Their functions in plants include antifungal activity (7), freezing tolerance, and protection against osmotic stress (8). Other features include binding to proteins, such as viral CMV-1 protein, yeast glycoproteins, and G protein-coupled receptor (GPCR), to hormones, such as cytokinins (5), and to glucanase (9) and xylanase (10).…”