Cytogenetic, physiological and agronomic characterization of wheat Thinopyrum ponticum recombinant lines carrying relevant breeding traits
Author(s)
Date Issued
March 22, 2011
Type
Doctoral Thesis
Abstract
An extensive molecular, cytogenetic and agronomic study was conducted on several available durum and bread wheat-Thinopyrum ponticum recombinant lines in order to identify, characterize and pyramid useful disease resistance and yield-related genes/QTLs on 7AL arm of wheat. From crosses made between bread wheat-Th. ponticum translocation lines resistant to Fusarium Head blight (FHB) and durum and bread wheat recombinant lines already possessing the leaf rust resistance gene (Lr19), the stem rust resistance gene Sr25 and the gene responsible for endosperm yellow pigmentation (Yp), BC1 progeny have been produced and selected for presence of all the three useful genes within a single genotype. In parallel, by means of chromosome engineering methodologies, a new durum wheat interstitial recombinant, named R5-2-23, was isolated, possessing about 20% of the Th. ponticum chromatin (=7AgL) on its 7AL arm, possibly harbouring a putative yield (Yld-7AgL) QTL. While this new durum wheat-Th. ponticum recombinant will contribute to dispose of stable lines in which fractions of the large 7AgL segment, originally associated with positive effects on yield, are separately present, already the use of some such lines in extensive agronomic and physiological analyses has shed some light onto the expression of important yield-related traits associated with 7AgL genes/QTLs, In fact, from a two years experiment, which included exogenous application of abscisic acid (ABA) on the first culm and field trials for assessment of yield-related parameters on whole plants, sub-regions on 7AgL chromatin expressing different yield-contributing traits have been identified. The durum recombinant lines used, i.e. R23-1, R112-4 and R5-2-10, carrying 40%, 28% and 23% of 7AgL onto their 7AL arm, respectively, showed differential phenotypes for traits recorded on the first culm and on whole plant, such as flag leaf width, ear length, spikelet number, seed number, culm number, biomass and grain yield. Line R112-4, in particular, resulted the most promising genotype in terms of overall yield potential, showing significantly increased values for flag leaf width (+10%), total tiller number at heading (+28%), total culm number at harvest (26%) and biomass (+30%), which contributed to a significantly higher yield (+34%), at least in the more favourable conditions of 2010. Physiological assays did not show any involvement of ABA in the expression of the Yld-7AgL QTL(s). No differential, 7AgL-dependent behaviour was exhibited by the same three durum wheat recombinant lines under imposed drought.
Additional information
Dottorato di ricerca in Biotecnologie vegetali
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