Supplementation with solutions of lipo-chitooligosacharide Nod Bj V (C18:1, MeFuc) and thuricin 17 regulates leaf arrangement, biomass, and root development of canola (Brassica napus [L.

Abstract

Recent work has shown that plant-to-microbe signals can enhance the growth of a wide range of crops. Nevertheless, canola (Brassica napus L.), which forms neither arbuscular mycorrhizal nor nitrogen-fixing symbioses, has not been rigorously evaluated for its capacity to perceive and respond to microbe-to-plant signals. It was shown previously that the Bradyrhizobium japonicum lipo-chitooligosaccharide (LCO) and Bacillus thuringiensis bacteriocin thuricin 17 enhance the germination and growth of other crop species. To evaluate canola’s response, B. napus plants were grown in controlled environment chambers, in either peat pellets or large plant culture vessels. In the peat pellet system, plants that were irrigated with 10−6 M LCO, and grown at 30 °C, produced one more leaf than water- or signal-treated plants that were grown at 25/20 °C. The numbers of cotyledons (seed leaves) produced by thuricin 17-treated plants was greater than LCO treated plants and the control treatment. Among the plants grown in vessels, those grown with 0.2 M NaCl and 10−9 M thuricin 17 were taller than either treated or untreated plants that were grown with 10−5 M NaCl. Under 10/4 °C and 4 × 10−5 M NaCl conditions, only seeds treated with thuricin 17 produced roots. Among the plants grown in vessels at 30/30 °C, those treated with 10−11 M thuricin 17 resulted in approximately one more leaf per plant than nM. Root lengths were shortened with 10−5 M NaCl and 10−9 M thuricin 17, compared to lower salinities. At 30/30 °C, plants grown with 10−5 M NaCl and 10−9 M thuricin 17 were heavier than plants grown in nonsaline media without thuricin 17. Where LCO supplementation may stimulate a competitive form, thuricin 17 supplementation triggers a reduction in the plant’s surface area, which may reduce the plant’s vulnerability to prohibitive salinity levels.