BIOFERTICELLULASER · Role of bacterial cellulases in the transition from free living to root endophytes in rapeseed crops and in the design of efficient biofertilizers

Role of bacterial cellulases in the transition from free living to root endophytes in rapeseed crops and in the design of efficient biofertilizers

According to FAO’s, in 2050 there will be an additional 2.3 billion people in the Planet, who will require producing more food, while at the same time combating existing poverty and hunger, using scarce natural resources more efficiently and adapting to climate change. Chemical fertilizers increase crops yields, but they have negative effects for human and animals health and the environment. Plant’s productivity can be enhanced by the activity of plant growth-promoting (PGP) bacteria, which are naturally-occurring bacteria able to modulate plant growth as a result of their metabolic activities. Nevertheless, apart from rhizobial strains applied to legume crops, most of the biofertilizers designed based on in vitro studies fail when applied in the fields. This failure could be due to the fact that, once applied in the soils, in vitro selected PGP bacteria must compete with a wide variety of microorganisms present in the soil and get adapted to the different abiotic conditions of each environment (temperature range, water/desiccation periods, etc.). This fact rises the interest of the PGP potential of bacterial endophytes -those bacteria with the ability to enter the endorhiza (root inside) –since, once inside the plant, they do not need to compete with the dense population of bacteria in the rhizosphere and they are protected from extreme abiotic conditions. Nevertheless, endophytic colonization, apart from the well-studied interactions between rhizobia and legumes, is not well understood. To shed further light in the mechanisms by which endophytes actively enter roots will likely allow great progresses in the wise selection of bacterial strains which can act as efficient biofertilizers in non-legume crops. Brassica napus L. (rapeseed) is an important crop due to its cultivation not only as food resource (human and animal), but also for biodiesel production. In Europe, the seeds of B. napus are the primary source of oil for biodiesel production. However, rapeseed cultivation requires important amounts of chemical fertilizers and therefore, alternatives that enable the reduction of chemical fertilization for a more sustainable crop are very desirable. This implies the use of biofertilizers, which include endophytic PGP bacteria. Thus, the aims of this project were: Isolation of B. napus PGP endophytes Identification of genes up-regulated during the infection process. Isolation of mutant strains in cellulase encoding genes. Study of symbiotic phenotypes of the mutant derivative strains. Analysis of the role of bacterial cellulases in PGP efficiency. Analysis of selected bacteria efficiency in infecting rapeseeds and increasing crop yields.

Data: CORDIS, © European Union