Short-Chain Chitin Oligomers: Promoters of Plant Growth

Chitin is the second most abundant biopolymer in nature after cellulose, and it forms an integral part of insect exoskeletons, crustacean shells, krill and the cell walls of fungal spores, where it is present as a high-molecular-weight molecule. In this study, we showed that a chitin oligosaccharide of lower molecular weight (tetramer) induced genes in Arabidopsis that are principally related to vegetative growth, development and carbon and nitrogen metabolism. Based on plant responses to this chitin tetramer, a low-molecular-weight chitin mix (CHL) enriched to 92% with dimers (2mer), trimers (3mer) and tetramers (4mer) was produced for potential use in biotechnological processes. Compared with untreated plants, CHL-treated plants had increased in vitro fresh weight (10%), radicle length (25%) and total carbon and nitrogen content (6% and 8%, respectively). Our data show that low-molecular-weight forms of chitin might play a role in nature as bio-stimulators of plant growth, and they are also a known direct source of carbon and nitrogen for soil biomass. The biochemical properties of the CHL mix might make it useful as a non-contaminating bio-stimulant of plant growth and a soil restorer for greenhouses and fields.Funding was provided in part by grants to Shauna Somerville from the Carnegie Institution of Science and the National Science Foundation, USA (#0114783). Alexander J. Winkler was funded by the Erasmus Program at Universidad Politécnica de Madrid (UPM). We acknowledge the kind contributions, at different stages of this project, of Fernando García Arenal, Pablo González Melendi and Mark Wilkinson from CBGP (UPM-INIA), Luis Díaz Balteiro and Carlos Calderón from MONTES, Carmen Muñoz from E.T.S.I. Forestales (UPM), Norma García from UPM and Elisabeth Magel from Hamburg UniversityWe acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)