The Presence of Arbuscular Mycorrhizal Fungi in the Rhizosphere of Transgenic Rapeseed Overexpressing a Trichoderma Thkel1 Gene Improves Plant Development and Yield

Abstract

Most of the plants belonging to the family of Brassicaceae are non-hosts for arbuscular mycorrhizal fungi (AMF). These plants are known to produce glucosinolates (GSL), a group of allelopathic compounds, with a role in plant defense. The overexpression of the Thkel1 from Trichoderma harzianum in rapeseed (BnKel) plants, this gene encoding a protein that shares similarities with Brassicaceae plant’s nitrile-specifier and epithiospecifier proteins, modified GSL metabolism, reducing the accumulation of toxic isothiocyanates due to hydrolysis of these secondary metabolites. Here, we have analyzed the effect of AMF application on the GSL profiles and the development and yield of BnKel plants. Our results showed that the reduction of GSL compounds on transgenic plants was not enough to allow the formation of arbuscules and vesicles characteristics of an AMF mycorrhizal association. However, the inoculation of transgenic rapeseed plants expressing Thkel1 with AMF improved seed yield and fatty acid composition of the oilseed, showing a beneficial effect of AMF in these plants. The achievement of this effective beneficial association among mycorrhizas and rapeseed plants opens new opportunities in agribiotechnology for the use of AMF as biofertilizers in Brassicaceae crops with potential application in medical, animal and industrial biotechnology.