Calogero Iacona

Novel Prunus rootstock somaclonal variants with divergent ability to tolerate waterlogging.

Plants require access to free water for nutrient uptake, but excess water surrounding the roots can be injurious or even lethal because it blocks the transfer of free oxygen between the soil and the atmosphere. Genetic improvement efforts in this study were focused on the increased tolerance in roots to waterlogging. Among a pool of clones generated in vitro from leaf explants of rootstock Mr.S.2/5 of Prunus cerasifera L., the S.4 clone was flood tolerant whereas the S.1 clone was sensitive. The S.4 clone formed adventitious roots on exposure to flooding. Moreover, the chlorophyll content and mitochondrial activity in the leaf and root, soluble sugar content, alcohol dehydrogenase activity and ethylene content were different between the clones. The sorbitol transporter gene (SOT1) was up-regulated during hypoxia, the alcohol dehydrogenase genes (ADH1 and ADH3) were up-regulated in the leaves and down-regulated in the roots of the S.4 clone during hypoxia, and the 1-aminocyclopropane-1-oxidase gene (ACO1) was up-regulated in the leaves and roots of the S.4 clone during hypoxia and down-regulated in the wild-type roots. In addition, in the S.4 root, hypoxia induced significant down-regulation of a glycosyltransferase-like gene (GTL), which has a yet-undefined role. Although the relevant variation in the S.4 genome has yet to be determined, genetic alteration clearly conferred a flooding-tolerant phenotype. The isolation of novel somaclonals with the same genomic background but with divergent tolerance to flooding may offer new insights in the elucidation of the genetic machinery of resistance to flooding and aid in the selection of new Prunus rootstocks to be used in various adverse environments.

Influence of rootstock on fruit entity, quality and antioxidant properties of fresh apricots (cv. ‘Pisana’)

The influence of two commercial Prunus rootstocks (‘Myrabolan 29/C’ and apricot ‘Seedling’) on fruit entity and quality of ‘Pisana’ apricot cultivar (Prunus armeniaca L.) was evaluated over two consecutive crop seasons. The effect of rootstock on the total antioxidant capacity, total phenols and physical-chemical traits of fresh apricots was studied at the ready-to-eat stage and after 14 days at 4 °C cold storage. The rootstocks had no significant influence on the flowering and fruiting entity but affected some fruit quality traits. The ‘Myrabolan 29/C’ appeared to induce the highest fruit weight, total antioxidant capacity and total phenols. The results showed an important role of the climatic conditions in determining the fruit antioxidant content. A drought ripening period improved the antioxidant potential of fruit independently of the rootstock. After cold storage, apricot fruits maintained good levels of antioxidants.