How can rhizobacteria support crop cultivation and how do they function?

Sammanfattning

As the global population is growing rapidly, and the amount of arable land is shrinking, food security stands out as one of humanity’s primarchallenges.Furthermore, the agricultural sector is a source of both harmful pollutants in the form of chemical pesticides, and nutrient leaching causing eutrophication. In this study, the utility of plant growth promoting rhizobacteria (PGPR) are considered in relation to crop growth and protection, highlighting their potential as contributors to food security. Moreover, ways in which PGPR might replace some conventional agricultural inputs, such as chemical pesticides and fertilisers, are explored. In relation to this, current obstacles to large scale implementation of PGPR are also discussed. In a second part of the study, the PGPR Bacillus velezensis UCMB5113 was examined as a root growth promoter and plant root coloniser. Specifically, roots of a wild type, two mutants and two transformants of Arabidopsis thaliana, as well as a cultivar of Brassica napus ssp. napus, were inoculated in vitro, and some root growth parameters, gene expressions and root surface components were assessed in relation to colonisation. Results indicated a root growth promoting effect in A. thaliana wild type and transformants and a stimulation of tertiary root formation in B. napus ssp. napus roots following inoculation with UCMB5113. However, due to uneven colonisation, results regarding the extent and effect of colonisation are inconclusive. Several reasons for the colonisation results are discussed. Nevertheless, the results remain largely unexplained, why some suggestions for further study are given.