Innovazioni del miglioramento genetico convenzionale e biotecnologico delle piante da frutto.

A heated debate is currently taking place in the scientific community about the use of two distinct breeding approaches: the conventional breeding (based on crossing and selection assisted by molecular-selective technologies such as MAS and MAB) and the breeding that uses the new techniques made available by the modern biotechnologies (an alternative or complementary way to reach goals that are not achievable by conventional breeding). This second approach allows the transfer of resistance genes to pathogens or to abiotic stresses (such as drought, salinity and weather anomalies) as well as the improvement of the fruit nutritional value without affecting the quality standards of cultivars. Today, in addition to the classic transgenic approach (GMOs), the new plant breeding technologies (NPBT), such as “genome editing” and cisgenesis, are available. The genome sequence of the main fruit tree species and the support of specific molecular markers for the identification of gene responsible for target traits made the breeding goals achievable in a much shorter time. Protocols for the analysis of molecular markers (SSR, SCAR, SNP) linked to monogenic and polygenic traits (eg. QTLs), such as fruit quality traits, their sensory features and the tree adaptability to environmental conditions are available. The new genotyping technologies allow the early selection at genome level in each single plant as well as the screening germplasm (ancient genetic heritage) looking for genes (or gene allelic variants) with the aim to recover traits that have been lost during crop evolution or because of an environmental selective pressure. Furthermore, the markers are useful to "build" customized fruits to prevent diseases or to improve fruit quality and storage. The potential offered by new plant breeding technologies to the current breeding of fruit tree species are certainly achievable by cisgenesis (but with the risk that the obtained plants will neither be admitted to field trials nor authorized for commercial release). As for genome editing (not to be confused with GMOs), the development of new technical CRISPR variants, adapted to fruit trees, is particularly crucial. In addition to the insertion of modification in the target regions and the guarantee of the absence of heterologous DNA, this will provide assurance on the variety genome preservation and the maintenance of the related fruit high quality standards.