Title : Applying combinatorial biotechnology in potato as an example of crop improvement.
Abstract:
The application of combinatorial biotechnology in potato improvement means to apply as many biotechnological tools and analytical methods as necessary in order to improve a crop. Potato is the most important vegetable in the world, being among the crops amenable for in vitro manipulation. Although, there are many cultivars obtained by classical breeding potato is still sensitive to many diseases and pests, which cause great yield loses each year. Climate change and population increase pose new challenges to potato breeders. Some examples of combinatorial schemes aimed at transferring resistance to late blight, Colorado potato beetle, potato virus Y (PVY) and drought are going to be discussed. The wild species Solanum bulbocastanum, which is sexually incompatible with the crop, was used as a source of resistance to late blight, Colorado potato beetle and drought. S. chacoense, another wild species which can be crossed with potato, was first transformed for inducing DNA mismatch repair (MMR) deficiency using Agrobacterium tumefacies carrying two different constructs (AtMSH2 gene as antisense – AS, or dominant negative- DN form). Both wild type and transgenic highest leptine producing accession of S. chacoense were used as a source of resistance to Colorado potato beetle and PVY. The initial accession was not tolerant to drought but after in vitro selection and phenotyping some of resulting somatic hybrid clones proved to be also tolerant to drought, a new trait caused by combining somatic hybridization and MMR deficiency. Some of the mechanisms involved in somatic hybridization, genetic stability and composition as well as biochemical signals involved in biotic or abiotic stress are also going to be discussed. The biotechnological tools used to produce pre-breeding clones and their analysis involved: transgenesis, somatic hybridization using protoplast electrofusion, selection of the somatic hybrid clones using molecular markers, back-crossing with potato crop and application of embryo rescue, analysis of the resistance traits, ploidy determination using direct and indirect methods, genome composition analysis with genome in situ hybridization (GISH), trichome types and density analysis, in vitro stress selection and phenotyping. The integration of those tools and analytical techniques allowed the selection of clones with multiple resistance traits representing a novel germplasm to be used in potato breeding programs.
