The use of micro-organisms as biofertilizers. Present and future use of transgenic micro-organisms in this area.

LUIS G. WALL

Paris

Conferencia; OECD Conference on the Environmental uses of micro-organisms; 2012

OECD

Biofertilizers are living microbial preparations which enhance or promote plant growth, relatively to a control without inoculation. A huge amount of research literature have been produced in the last 20 years concerning Plant Growth Promoting Rhizobacteria (PGPR) related subjects, describing different microorganisms acting on different plants, and proposing different mechanisms to explain the plant growth promotion effect. Two mode of action can be recognized: 1) Direct action on the plant physiology, enhancing plant growth and development; 2) Indirect action via mitigation of a stressed plant condition, because of biotic (disease) or abiotic (environmental) factors. Mechanisms of biofertilizers include: 1) plant nutritional effects; 2) production of phythormones; 3) mitigation of environmental stress condition. Many different bacteria genera have been described as PGPR. Despite we still did not know which of the different in vitro described mechanisms of Biofertilizer action are responsible for the positive effects in the field, Biofertilizer technology have significantly developed in the market. The nature of multiple mechanisms discovered for PGPR actions, and the possibility of genetically modification of a particular strain concerning a particular plant growth promoting activity, suggest that the use of genetically modified organisms as Biofertilizers will be an area of multiple and diverse possibilities of action in the near future. The study of the microbial ecology of this scenario and its dynamics will certainly improve the development of biofertilizers technology for the future of agriculture.