Partially Acetylated Chitosan Oligo- and Polymers Induce an Oxidative Burst in Suspension Cultured Cells of the Gymnosperm Araucaria angustifolia

Abstract

Suspension-cultured cells were used to analyze the activation of defense responses in the conifer A. angustifolia , using as an elicitor purified chitosan polymers of different degrees of acetylation (DA 1-69%), chitin oligomers of different degrees of polymerization (DP 3-6), and chitosan oligomer of different DA (0-91%). Suspension cultured cells elicited with chitosan polymers reacted with a rapid and transient generation of H2O2, with chitosans of high DA (60 and 69%) being the most active ones. Chitosan oligomers of high DA (78 and 91%) induced substantial levels of H2O2, but fully acetylated chitin oligomers did not. When cultivated for 24-72 h in the presence of 1-10 microg mL(-1) chitosan (DA 69%), cell cultures did not show alterations in the levels of enzymes related to defense responses, suggesting that, in A. angustifolia , the induction of an oxidative burst is not directly coupled to the induction of other defense reactions.

Oligochitosan: A plant diseases vaccine—A review

“…Besides the plants and diseases we mentioned hereinbefore, it has also been reported that oligochitosan can activate plant defense to other diseases on several other plants such as barley (Faoro, Maffi, Cantu, & Iriti, 2008), pearl millet (Manjunatha, Roopa, Prashanth, & Shetty, 2008), carrot (Molloy, Cheah, & Koolaard, 2004), sunflower (Nandeeshkumar et al, 2008), coconut (LizamaUc et al, 2007), araucaria (Dos Santos, El Gueddari, Trombotto, & Moerschbacher, 2008), etc. In the general survey in more than 20 provinces in China, we found that oligochitosan had plant immunity regulation activity in 24 plants (Table 1).…”

Expression of a bacterial chitosanase in rice plants improves disease resistance to the rice blast fungus Magnaporthe oryzae

“…Natural chitosan is not considered fully deacetylated (Saito et al 2009), and thus N-acetylchitooligosaccharides could be generated from chitosan through Cho1. In fact, partially acetylated chitooligosaccharides, as well as N-acetylchitooligosaccharides, induce ROS generation (dos Santos et al 2008). Therefore, in ?SS plants, apoplastic Cho1 may hydrolyze chitosan in the cell wall of M. oryzae and result in the increased production of both N-acetylchitooligosaccharides and partially acetylated chitooligosaccharides, which induces higher levels of ROS generation.…”

Biotechnological approaches for field applications of chitooligosaccharides (COS) to induce innate immunity in plants

“…with increasing positive charge density ; however, this is not always true (Vander et al, 1998). As mentioned above, plants do not appear to secrete chitosanases, but their chitinases may well partially depolymerize fungal chitosan to produce partially acetylated chitosan oligomers that possess ecilitor activity (dos Santos et al, 2008).…”

“…the number and sequence of acetylated and deacetylated units. The DP, DA and concentration of the COS strongly affect their elicitor activities (Day et al, 2001, dos Santos et al, 2008Hadwiger, 1999;Yamada et al, 1993). Elicitor activity of COS also varies depending on the plant.…”

“…chitin oligomers, induce a broad-spectrum defense responses while fully deactelyated COS tend to be inactive as an elicitor (Vander et al, 1998;Wei et al, 2004). The elicitor activity of partially acetylated COS has rarely been studied, but they may in some cases be more potent than their fully acetylated counterparts (dos Santos et al, 2008). COS of low DA were better for direct inhibition of pathogen growth, whereas spray or seed treatment with COS of higher DA proved better to protect tobacco against Phytophthora parasitica by systemic induction of plant resistance (Falcón et al, 2008).…”