Detalle de: Estrategias de control biológico eficientes contra Rosellinia necatrix: de la genómica funcional al campo

The goal of this coordinated project is to move forward into the different strategies developed for effective biological control of avocado white root rot, caused by the fungus Rosellinia necatrix. To this end, the knowledge acquired so far will be applied on the different partners that interact within this system, with the aim of approximating the effective biocontrol of the disease. The hipovirulent isolates of R. necatrix and related fungi may be carriers of dsRNA segments and be capable of transmitting hypovirulence to pathogenic isolates. A low presence of nonpathogenic isolates of R. necatrix has been detected in field surveys, however, some new fungi identified as Entoleuca sp, a genus close to Rosellinia and which infest escape avocado tree soils, have appeared. Some strains of this genus are not pathogenic in avocado plants and provide biocontrol action against avocado white root rot. Therefore, this fungal genus is going to be subject of study to discern the role of the mycovirus of Entoleuca sp. in the biological control of this disease, while developing applications in the field of commercial formulations of the antagonist fungus Trichoderma, which provides strains with potential biocontrol activity of the disease. On the other hand, and using as a model the biocontrol bacterium Pseudomonas chlororaphis PCL1606, we will get insight into the interactions that take place during biocontrol. Thus, different techniques ranging from functional genomics to cell biology will be used to study "quorum sensing" regulation and its role in the biocontrol of Rosellinia necatrix by PCL1606. In addition, the first approaches to the use of Pseudomonas chlororaphis PCL1606 as commercial biocontrol agent will be carried out. To do this, this strain will be formulated as a commercial-like product, and applied to microcosmos tests on avocado plants. Aspects such as protection against R. necatrix, the effect of its application on the soil microbiota or the mobility of the bacteria into the experimental system will be studied. Depending on the results obtained, the first application trials of P. chlororaphis on commercial orchards could be scheduled. Finally, the regeneration of avocado plants via somatic embryogenesis from adult explants (stem apices and seed coat) will be attempted, in order to be able to carry out the manipulation of material with good agronomical traits as well as to evaluate if there is a recovery of the morphogenetic ability, which would facilitate the in vitro multiplication of shoots of adult origin. At the same time, the obtainment of tetraploid plants will be carried out from embryogenic cultures selected in the current project, as well as as from cultures resistant to the filtrate of R. necatrix, in order to evaluate if plants with higher level of ploidy would show smaller size and higher plasticity when facing stress. In addition, the optimization of the cold storage protocol will be continued to allow a reliable presevation of embryogenic cultures. Finally, the behavior of transformed material with the AtNPR1 gene against R. necatrix, in the presence of antagonistic microorganisms previously selected in this project, will be evaluated.