Comparison of Proteinase Inhibitor-Inducing Activities and Phytoalexin Elicitor Activities of a Pure Fungal Endopolygalacturonase, Pectic Fragments, and Chitosans

Abstract

Rhizopus stolonifer endopolyglacturonase, an elicitor of casbene synthetase activity in castor bean seedlings, was found to be a potent elicitor of the phytoalexin pisatin in pea pods and of proteinase Inhibitor I in tomato leaves. The enzyme was an active elicitor or inducer only in its active native state; heat-denatured enzyme was inactive in all three systems. The activities of (a) the tomato pectic polysaccharide proteinase inhibitor-inducing factor, (b) a partially acid hydrolyzed proteinase inhibitor-inducing factor, (c) citrus pectic fragments, and (d) chitosan, were also compared in the three bioassay systems. The four oligosaccharide preparations were active in all three systems, but with different degrees of potency. In tomato leaves and pea pods, chitosans were most active, whereas in castor beans, the citrus pectic fragments were the best elicitors. The data presented support the hypothesis that plant and funpl cell wall fragments are important signals in mobilizing a wide variety of biochemically different types of plant defense responses, and that endopolygalacturonases play a key role in releasing the plant cell wall fragments during pest attacks.

A Review of the Applications of Chitin and Its Derivatives in Agriculture to Modify Plant-Microbial Interactions and Improve Crop Yields

“…Numerous genetic and physiological studies show a clear link between jasmonate signalling and the induction of local and systemic defenses in plants. In addition to elevated jasmonate levels, exogenous methyl-jasmonate application also activates many of the same systemic responses [107,[115][116][117] and genes [115,118,119] as chitin-based treatments in plants, which also indicates a link between chitin treatment and jasmonate activation of defenses. Elevations in the level of the stress hormone ABA has also been found following chitin-based treatments [120] and both are known to reduce stomatal aperture [121].…”

The Biochemical Response of Electrical Signaling in the Reproductive System of Hibiscus Plants

“…However, only the stigma w a s wounded 8 to 10 c m from the ovary. With regard to wound reactions, it also has been shown that membrane properties do change in leaves that are distant from those wounded, resulting in the formation of more fragile protoplasts (Walker-Simmons et al, 1984). Other authors (Gaspar et al, 1985) suggested that stress-induced membrane depolarization leads to generation of free radicals and peroxides, which cause breakdown of membrane lipids.…”

The sink-specific and stress-regulated Arabidopsis STP4 gene: enhanced expression of a gene encoding a monosaccharide transporter by wounding, elicitors, and pathogen challenge.

“…This detected elicitation could, however, be due partly to chitin oligomers that may have been released from the insoluble chitin by enzymes secreted by the suspension-cultured cells (Felix et al, 1993). Chitin oligomers have been shown to act as potent elicitors of protease inhibitor and chitinase activities, of polyphenolic compounds, and of severa1 phytoalexins (Kohle et al, 1984;Walker-Simmons et al, 1984;Roby et al, 1987).…”