Laticifer proteins play a defensive role against hemibiotrophic and necrotrophic phytopathogens

Abstract

Proteins from latex of Calotropis procera (CpLP), Plumeria rubra (PrLP), Carica candamarcensis (P1G10) and Euphorbia tirucalli (EtLP) were tested for antifungal activity against phytopathogens. CpLP and P1G10 inhibited each fungi analyzed. PrLP and EtLP did not exert inhibition. CpLP and P1G10 exhibited preferential inhibitory activity towards R. solani (IC₅₀ = 20.7 and 25.3 µg/ml, respectively). The inhibitory activity was lost after heat treatment or proteolysis, providing evidence for the involvement of proteins in the inhibitory effect. Treatment of CpLP or P1G10 with Dithiothreitol improved both, the endogenous proteolytic activity and the antifungal properties. Conversely, pre-treatment of CpLP or P1G10 with iodoacetamide drastically reduced endogenous proteolytic activities and partially abrogated antifungal activity. Similar results were observed when spores were challenged to germinate in the presence of laticifer proteins. The purified cysteine proteinase CMS2MS2 from Carica candamarcensis latex or papain (E.C. 3.4.22.2), a cysteine proteinase from latex of Carica papaya L., but not trypsin (EC 3.4.21.4) or chymotrypsin (EC 3.4.21.1), two serine proteases, replicated the results obtained with CpLP or P1G10, thus restricting the antifungal property to latex plant cysteine proteinases. CpLP, CMS2MS2 and papain induced production of reactive oxygen species in spores of F. solani, suggesting that inhibition could be linked to oxidative stress. Proteome analysis of CpLP by 2-D electrophoresis and MALDI-TOF-TOF confirmed the existence of various pathogenic-related proteins such as chitinases, peroxidases and osmotins. The results support that laticifer proteins are part of plant defense repertoire against phytopathogenic fungi.

Plumeria rubra L. (Apocynaceae): Ethnobotany, Phytochemistry and Pharmacology: A Mini Review

“…The plant has been investigated for antibacterial (Hamburger et al, 1991;Egwaikhide et al, 2007Egwaikhide et al, , 2009Kuigoua et al, 2010;Baghel et al, 2010;Dey et al, 2011), antifungal (Kuigoua et al, 2010;Souza et al, 2011;Gaitan et al, 2011), antimicrobial (Mahady, 2002), antialgal (Kuigoua et al, 2010), larvicidal (Ramos et al, 2009;Patil et al, 2012), molluscicidal (Hamburger et al, 1991), piscicidal (Joshi and Joshi, 2006), nematicidal (Joymati, 2010), antioxidative and free radical scavenging activities (Ruiz-Teran et al, 2008), hypolipidemic (Merina et al, 2010), proteolytic (De Freitas et al, 2010), cytotoxic (Kardono et al, 1990;Hamburger et al, 1991;Rekha and Jayakar, 2011), abortifacient (Dabhadkar and Zade, 2012) and anti HIV (Tan et al, 1991) properties. The biocatalytic activity in terms of lipase activity in hydrolysis and acyl transfer reactions of latex was compared with that of babaco (Vasconcellea x Heilbornii Cv.)…”

“…Fulvoplumierin was also found to inhibit HIV 2 (Tan et al, 1992). Latex proteins from the plant were investigated for antifungal property against plant pathogens along with some other latex bearing plants (Souza et al, 2011). Potentiality of laticifer proteins for larvicidal activity against Aedes aegypti was tested (Ramos et al, 2009).…”

Plant latex: A natural source of pharmaceuticals and pesticides

“…It is considered as analogous to animal venom because it contains cysteine proteases, which provide defense against herbivorous insects (Kitajima et al) [8] and phytopathogenic fungi. [27] Similarly, both osmatin and thumatin proteins isolated from Calatropis procera, were found effective against fungi Fusarium solini (IC 50 67 µg/ ml), Nurospora (IC 50 C 57.5 µg/ml), and Collettricum gloesoriodes 32.1 µg/ ml). [28] Similar activity is reported in Pulmera rubra, and Euphorbia tirucallai latex proteins against phytopathogens.…”

“…[28] Similar activity is reported in Pulmera rubra, and Euphorbia tirucallai latex proteins against phytopathogens. [27] Similarly, a protein secreted peroxidase class III isolated from Euphorbia characias acts as a catalytic enzyme. [23] More usually, plant latex contains defense protein MLX56 and cardenoides, which operate inducible defense in infected plants [29] and also show complicated molecular interactions to herbivores.…”

A new peptide from Jatropha curcas seeds: Unusual sequence and insights into its synthetic analogue that enhances proteolytic activity of papain

“…Inhibition of spore germination and vegetative growth of phytopathogenic fungi (Fusarium solani and Rhizoctonia solani) were performed according to the method reported previously [16].…”