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

Abstract

Plants have evolved mechanisms to recognize a wide range of pathogen-derived molecules and to express induced resistance against pathogen attack. Exploitation of induced resistance, by application of novel bioactive elicitors, is an attractive alternative for crop protection. Chitooligosaccharide (COS) elicitors, released during plant fungal interactions, induce plant defenses upon recognition. Detailed analyses of structure/function relationships of bioactive chitosans as well as recent progress towards understanding the mechanism of COS sensing in plants through the identification and characterization of their cognate receptors have generated fresh impetus for approaches that would induce innate immunity in plants. These progresses combined with the application of chitin/chitosan/COS in disease management are reviewed here. In considering the field application of COS, however, efficient and large-scale production of desired COS is a challenging task. The available methods, including chemical or enzymatic hydrolysis and chemical or biotechnological synthesis to produce COS, are also reviewed.

• Chitooligosaccharides
• crop protection
• induced resistance
• PAMPs
• transglycosylation

Acknowledgements

We thank the European Union for financial support in the framework of its NanoBioSaccharide and NBS-TTC projects. We also thank Deutscher Akademischer Austauschdienst (DAAD) and Deutsche Forschungsgemeinschaft (DFG) for supporting our Indo-German collaborations, e.g. through the Indo-German International Research Training Group on Molecular and Cellular Glyco-Sciences, MCGS. A.R.P. thanks the Department of Biotechnology (DBT)-CREBB and UGC-CAS programmes of School of Life Sciences and DST-FIST Level II support to the Department of Plant Sciences, University of Hyderabad, for the infrastructure support. A.R.P. also thanks DBT, Government of India, for the financial support in the form of a major research project on “Elicitor-loaded nanoparticles for crop protection”. B.M.M. thanks the European Union for financial support through its PolyModE project. S.N.D, J.M.P, K.S. and M.K. thank CSIR for Senior Research Fellowships, P.V.S.R.N.S. and S.R. thank DBT for Research Fellowships and PP thanks UPE-II, University of Hyderabad for a Postdoctoral Research Fellowship.

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.