Age-Dependent Variations of Volatile Emissions and Inhibitory Activity Toward Botrytis cinerea and Fusarium oxysporum in Tomato Leaves Treated with Chitosan Oligosaccharide

Abstract

We investigated variations in the level and composition of volatiles emitted by tomato leaves at different ages. Our focus also included their antifungal properties and responses to chitosan oligosaccharide. Based on leaf position, the release of volatiles decreased over time. Young leaves produced high levels of C6-aldehyde, which is mainly composed of hexenal, while the volatiles emitted by more mature leaves largely comprised terpenes, particularly β-phellandrene and caryophyllane. In young upper leaves, the main components (up to 86% of the total) were hexenal, β-phellandrene, and caryophyllane. Their levels decreased steadily over time, from 386.3 μg g −1 fresh weight (FW) in young leaves to 113.2 μg g −1 FW in old tissues. Volatiles emitted from young leaves exhibited the best antifungal activity against spore germination and hyphal growth by Botrytis cinerea and Fusarium oxysporum. Leaves became more susceptible to oligosaccharide treatment with increasing age. When young tissues were exposed to chitosan, we found declines in both the quantity of volatiles and their ability to inhibit fungal growth. Compared with the control, the amount of volatiles from young tissues was 88.4% lower after such treatment. In contrast, contents of volatiles from old and adult leaves were dramatically increased by chitosan oligosaccharide. Likewise, their inhibitory effect was significantly enhanced. Therefore, our results suggest that these volatiles are responsible for antifungal activity and may play a role in age-related resistance by tomato.

Oligochitosan: A plant diseases vaccine—A review

“…Other studies indicated that oligochitosan had the ability to protect tomato plants against Colletotrichum sp. and Fusarium oxysporum (Zhang & Chen, 2009). For example, oligochitosan inhibited the radial growth of Colletotrichum sp., with marked effect when the concentration exceeds 1.5%.…”

“…0.1% oligochitosan induced production of not only simple coumarins but also furanocoumarins and dihydrofuranocoumarins. In a recently published paper, the level and composition of volatile secondary metabolites in tomato leaves were analyzed after oligochitosan treatment (Zhang & Chen, 2009). Compared with the control, the amount of volatiles from old and adult leaves was dramatically increased by oligochitosan.…”

Chitosan Oligosaccharides Promote the Content of Polyphenols in Greek Oregano (Origanum vulgare ssp. hirtum)

“…19 However, a 0.5% COS solution was reported to have no effect on the content of terpenoids in tomato. 18 These reports suggest that the ability of COS to induce secondary metabolites varies in different plant systems. The response may vary from plant to plant and depend upon many factors, such as the concentration of COS, growth stage, timing of elicitor, and contact time of elicitation.…”

Pre-harvest spray of oligochitosan induced the resistance of harvested navel oranges to anthracnose during ambient temperature storage

“…It has been demonstrated that pre-or post-harvest oligochitosan treatment can induce plant resistance to pathogenic infections by activating various defensive reactions, such as directly affecting spore germination and germ tube elongation of pathogens, stimulating defense-related enzymes, and enhancing antifungal activities of plant volatiles (Zhang and Chen, 2009;Meng et al, 2010b;Yan et al, 2012). Previous work indicated that oligochitosan and chitosan effectively controlled anthracnose development in banana .…”

“…Values followed by different letters at the same time are significantly different according to Student's t-test (*P ¼ 0.05). Zhang and Chen (2009) with slight modifications. In brief, approximately 15 mL of the spore suspension of C. gloeosporioides was placed on the surface of a 1.0 cm 3 block slide, which was immersed in a PDA medium at 55 Ce60 C before use.…”