Caratterizzazione morfo-genetica con metodi biometrici e molecolari e applicazioni di tecniche colturali innovative su una collezione di germoplasma di Hydrangea spp.
Author(s)
Lazzereschi, Sara
Date Issued
June 7, 2013
Type
Doctoral Thesis
Abstract
The PhD is about the activities carried out within the research project ‘Valorization for commercial purposes of Hydrangea (acronym: Hydra)’ financed by MiPAAF (Bando Imprese Florovivaismo, D.M. 186 of 1 August 2007, published in the Official Gazette No. 208 of 7/09/2007).
The doctoral research focused on the morpho-genetic characterization through molecular and biometric methods and applications of innovative cultivation techniques on a Hydrangea spp. collection, in addition to the development of an in vitro protocol for the conservation of germplasm and preliminary breeding trials applied to the genre.
At CRA-VIV in Pescia a Hydrangea spp. collection was set up: different species, distributed evenly under black nets with different shading percentage, have been the subject of a morphological and genetic characterization. The morphological characterization was performed using 27 UPOV descriptors specific to the genre in order to study the diversity and relationships of the various species. So a dendrogram was obtained containing the relationships between the genotypes stored in the collection. This characterization was supplemented with a genetic characterization, to get a general screening on the collection species. This analysis was carried out using RAPD molecular markers, which are simple and effective fingerprinting methods. Regarding the reproducibility of the technique, this has been verified in independent experiments and confirmed by repeating the amplifications, so as to analyze only those markers which resulted reproducible: it was possible to identify 248 RAPD markers of different sizes from 200 to 1100 bp and all polymorphic. The phylogenetic analysis was conducted using pc2.02 NTSYS (Exeter Software, Setauket, NY) and MEGA 4.0 programs; on the basis of these data a dendrogram was obtained according to the Neighbor-Joining method.
To modify the spectrum of solar radiation that reaches the crop, and study the morphogenesis plant response, through the use of selective colored net, the collection was reorganized. In particular, the black nets were replaced with blue and red colored nets with 70% of shading and compared with a traditional black net, also with 70% of shading. All species included in the collection were evenly distributed in the
different colored nets, in order to obtain replicas of the same cultivars under three shadings, and some of them have been the subject of study. Light intensity was carried out under each net by Luxmeter. To monitor the light conditions to which the plants were exposed, spectra of total solar light energy level were measured under each net by a spectroradiometer. The following morphological and physiological effects on plants were made: photosynthesis, CO2 internal content, stomatal conductance and evapotranspiration; leaf area (LAI Leaf area index); total height of the plant and internode length; leaf variegation only for those varieties with variegated leaves.
An in vitro propagation protocol suitable for high-quality and large scale production of the most promising species of Hydrangea has also been developed, in order to verify the efficiency of production, compared to traditional techniques of propagation. The protocol involved the sterilization phases of the explants, multiplication and rooting in vitro and acclimatization. The validity of the micropropagation protocol was confirmed: it allows to obtain good rates of multiplication and rooting, as compared to other protocols already described in the literature for other species of Hydrangea.
In addition, an investigation was carried out on intra- and interspecific compatibility of some species in order to obtain new hybrids with innovative characteristics, suitable for cut flowers production. Intra-and interspecific crosses and autoimpollination were made with the goal of identifying those genotypes used as male/or female parental and to obtain information on the degree of fertility/self-sterility.
Additional information
Dottorato di ricerca in Ortoflorofrutticoltura
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