http://http://dspace.unitus.it:80 The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material. Tue, 21 May 2013 12:33:01 GMT 2013-05-21T12:33:01Z http://hdl.handle.net/2067/2181 Title: Olea Authors: Rugini, Eddo; De Pace, Ciro; Gutierréz-Pesce, Patricia; Muleo, Rosario Abstract: The genus Olea contains about 30 species were grouped into three subgenera, Tetrapilus, Paniculatae, and Olea (cultivated olive and wild relatives), found in Asia, Australia and Asia, Africa and Europe, respectively. The species O. europaea L. includes six subspecies: Olea europaea L. ssp. europaea (the Mediterranean olives); O. e. laperrinei (distributed in Saharan massifs of Hoggar, Aïr, Jebel Marra in Algeria); O. e. cuspidata (which moved from South Africa to Egypt, East Australian areas and Hawaii, and from Arabia to northern India and Southwest China); O. e. guanchica (Canary Islands); O. e. maroccana (southwestern Morocco); and O. e. cerasiformis (Madeira). Using molecular markers, it has been ascertained that the Mediterranean olives include the cultivated types (O. europaea L. ssp. europaea var. sativa), the true wild oleaster (O. e. e. var. sylvestris), and the feral form olevaster from seedlings raised from seeds of the cultivated types. The oleaster has a narrow range of distribution and it is often mistaken for olevaster. Recolonization of the Mediterranean basin by Oleaster occurred after the last glacial event, from refuges located in both eastern and western Mediterranean basin areas toward southern Europe. Oleaster is a source of rootstock for propagating new improved cultivated varieties. Cultivated and wild forms have the same diploid chromosome number (2n = 46) and are fully interfertile. Triploid and tetraploid genotypes have been isolated from cultivated O.e.e., but polyploid forms have been found in endangered natural populations of O. e. guancica (tetraploid) and O. e. maroccana (hexaploid). Individual oleaster trees showing superior performance for size and/or oil content of fruit were selected empirically during olive domestication and propagated vegetatively as clones using cuttings that were planted directly or, more recently, grafted onto indigenous oleasters. Genetic markers linked for most important agronomic traits, such as size of the tree, content of secondary products of fruit, flowering induction, oil quality, and biotic and abiotic resistance, will help introgression by conventional breeding of oleaster trait-enhancing genes into cultivated olive. Successful results were difficult to achieve due to both the complex genetic basis of the traits to be improved and the long juvenile period of the progenies that delays the expression of the target traits. In vitro techniques to regenerate doubled haploids from hybrids or somaclonal variation induction may complement classical breeding procedures. Genetic transformation could speed up the development of new genotypes, and transgenic olive plants with modified growth habit and putative induced disease resistance are being tested under filed conditions. However, the development of an efficient regeneration method from mature tissue is the limiting factor for the routine application of this technology to olive genetic improvement. Description: L'articolo è disponibile sul sito dell'editore http://www.springerlink.com Fri, 31 Dec 2010 23:00:00 GMT http://hdl.handle.net/2067/2181 2010-12-31T23:00:00Z http://hdl.handle.net/2067/2171 Title: Influence of plant growth regulators, carbon sources and iron on the cyclic secondary somatic embryogenesis and plant regeneration of transgenic cherry rootstock ‘Colt’ (Prunus avium x P. pseudocerasus) Authors: Gutierréz-Pesce, Patricia; Rugini, Eddo Abstract: The frequency of long-term secondary somatic embryogenesis and shoot meristem development from embryogenic masses of the cherry rootstock ‘Colt’ (Prunus avium x P. pseudocerasus), differentiated from transgenic roots containing the T-DNA of Agrobacterium rhizogenes, has opened the way for genetic improvement by biotechnological techniques. Whole plants were produced by stimulating shoot meristem development from somatic embryos. The combination of 4 mg 1¯¹ of kinetin and 2% of maltose under illumination stimulated shoot development and, subsequently, whole plants have been recovered by applying 1.5 mg 1¯¹ kinetin to the rooting medium. Although numerous treatments have been tested involving both embryogenic masses and whole embryos, normal embryo germination was observed sporadically. Cold treatment was effective in stimulating secondary somatic embryogenesis with embryo development to the cotyledonary stage, but did not promote their germination. Similarly, a higher concentration (44–55 mg 1¯¹) of chelated iron than that commonly used in tissue culture media (36.7 mg 1¯¹) produced, after 3 weeks in culture, almost a 50% increase in the number of embryos at the cotyledonary stage per embryogenic mass. Among the cytokinins tested, 1 mg 1 ¯¹ of 6-benzylaminopurine and 0.1 mg 1¯¹ of thidiazuron were effective in inducing secondary somatic embryogenesis; however, each of them expressed highest efficiency with specific medium and environmental conditions. Furthermore, application of 1 mg 1¯¹ thidiazuron reverted morphogenic callus to non-morphogenic callus, particularly in medium containing 2% sucrose. Finally, hormone free medium with 2% maltose enhanced maturation of the embryos to the normal cotyledonary stage. This paper has improved knowledge of embryo culture and plant production in this important genotype, opening the way for genetic improvement by biotechnological techniques, mainly with the aim of modifying the growth pattern of the canopy of sweet cherry grafted on it. Description: L'articolo è disponibile sul sito del nuovo editore http://www.springerlink.com Wed, 31 Dec 2003 23:00:00 GMT http://hdl.handle.net/2067/2171 2003-12-31T23:00:00Z