Trasferimento di geni da specie selvatiche a frumento tramite ingegneria cromosomica: potenzialità di questa strategia ed eventuali ostacoli
Author(s)
Grossi, Maria Rosaria
Date Issued
February 26, 2010
Type
Doctoral Thesis
Abstract
Transfer of the useful genes from alien Triticeae species to cultivated wheats is nowadays a
breeding approach of great potential, mainly if currently feasible fine strategies of “smart”
chromosome engineering are applied. The term of “chromosome enigeering” implies complex
cytogenetic methodologies that enable to engineer the wheat genome with alien chromosome
segments carrying target alien gene(s). These can nowadays benefit from the recent developments
of marker technology and genomics, which provide highly effective tools to develop highresolution
genetic maps and apply marker-assisted selection, as well as in situ hybridization
techniques, to define the physical localization and length of the transferred segment.
Relationships of synteny and colinearity largely characterizing Triticeae genomes, as well as use of
genetic systems of promotion of recombination between homoeologous Triticeae chromosomes,
allow attainment of usually well compensated products. An expected, by reducing the amount of
alien chromatin associated to the target gene(s), the probability of co-trasfer of unwanted genes
(linkage drag), particularly if the donor species belongs to the wild genepool, is minimized. A very
efficient characterization of recombinant products is thus feasible, hence selection of those carrying
the target genes associated to the shortest possible segments.
Such a “smart” (or “precision”) chromosome engineering as been successfully and originally
applied to produce durum wheat-Th. ponticum recombinant lines (a perennial wild Triticeae
species). Such recombinant lines differ for the size of 7AgL portion transferred onto the durum
7AL.
The aims of this project were the evaluation of the impact of chromosome engineering on a
7AL/7AgL recombinant line, named R23-1, carrying Lr19 (a highly effective resistance gene to leaf
rust), Yp (able to increase endosperm and semolina carotenoid pigment content) and a potential
yield QTL (Yld-QTL) and the production of a 7AL/7AgL chromosome containing three target
genes, well tolerated by the recipient genome. Such recombinant line appears to suffer from a
reduced transmission through the male germiline. Analyses carried out on these lines to verify their
impact at gametic and sporophytic levels. Similar evidence was previously reported in studies of
common wheat recombinant chromosomes harbouring different amount of 7AgL, in which the
defect was ascribed to a Th. ponticum gene named Sd1 (Segregation distortion), located proximally
with respect to Lr19 and Yp.
Additional information
Dottorato di ricerca in Biotecnologie vegetali
Subjects
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