Proceedings of the XLVI Italian Society of Agricultural Genetics - SIGA Annual Congress

Giardini Naxos, Italy - 18/21 September, 2002

ISBN 88-900622-3-1

Poster Abstract - 4.08

Wheat STMS markers provide a valid and informative tool for the genetic profiling of elite durum wheat cultivars

Maccaferri M.*, TERIACA M.*, Donini P.**, Noli E.*

*) DiSTA, Università di Bologna, Italy

**) National Institute of Agricultural Botany, Cambridge, U.K

durum wheat, microsatellites, fingerprinting, macro-haplotype, graphical genotyping

The durum wheat elite gene-pools cultivated in Southern-Europe, U.S. and Canada, with particular emphasis on the Italian germplasm, have been characterised by a whole-genome molecular profiling based on microsatellite (STMS) markers. In total, 134 accessions, mainly modern cultivars (cvs.), were characterised with 70 STMS loci (mostly dinucleotides) of known map position, covering ca. 80% of the wheat A and B genomes. Different levels of genetic diversity were present within and among the gene-pools of different origin. The use of a map-based genotyping approach allowed a chromosome by chromosome display of the genetic relationships among cvs. and breeding groups; this, coupled with the high polymorphism level of STMS markers, allowed us to follow the inheritance and spread of specific alleles firstly introduced by relevant founders as well as entire genomic regions (“macro-haplotypes”) within and between breeding lineages; the relative contribution of each founder to the genetic profiles of modern cvs. and the frequency and distribution of rare alleles are discussed. The graphical genotypes of modern cvs. were highly informative as to their genealogy: each cv. displayed a unique genetic make-up which resulted from the combination of several diverse “macro-haplotypes”, peculiar of the main breeding lineages and spanning up to several tens of cM on the wheat genetic map. These large “founder-signatures” inherited with little rearrangements from recent founders to modern cvs. allow for the identification of the putative parents, when included in the profiled collection, of a cv. and even the roughly quantification of their relative genetic contribution. Such genetic information is valuable for cv. identification and plant breeder’s right protection (essential derivation) issues, particularly in case of inaccurate or cryptic pedigree information. Also, genetic similarity information would be particularly helpful for the management of the reference collections in the DUS (Distinctness, Uniformity, Stability) testing framework. However, as high throughput, robustness and celerity are among the requirements of these analyses, a limited set of 20 primer pairs is being tested for partial multiplexing. This set of primers showed a high accuracy for investigating the genetic distances in the genotypes herein considered, as indicated by the high coefficient of correlation (0.91) between the pair-wise genetic similarity matrices obtained with these 20 STMSs and the complete set of 70 STMSs.