Genetic relationships and clonal identity in a collection of commercially relevant poplar cultivars assessed by AFLP and SSR

Abstract

A collection of 66 poplar commercial clones widely cultivated in Italy, China and in other countries of southern Europe and belonging to various poplar species and hybrids, have been fingerprinted using both amplified fragment length polymorphism (AFLP) and simple sequence repeats (SSR) techniques. Three AFLP primer combinations and six SSRs unambiguously genotyped the analysed poplar collection, with the exception of three groups of six, four and two individuals, which turned out to be indistinguishable even if they met the standards currently applied for distinctness, uniformity and stability (DUS) testing when registered. High levels of variation were detected with both\ud molecular techniques; a total of 201 AFLP bands were\ud amplified of which 96% turned out to be polymorphic and\ud up to 15 SSR alleles were identified at a single locus, with\ud a mean of 9.3 alleles per locus in the case of Populus ×\ud canadensis. The probability of matching fortuitously any\ud two genotypes at all the SSR loci in the case of P. ×\ud canadensis was less then 7.5×10− 9. The AFLP-derived\ud dendrogram and principal coordinate analysis (PCOOR-\ud DA) clustered the clones with respect to their taxonomic\ud classification, and allowed their genetic interrelationships\ud to be established. Correct identification of poplar varieties\ud is essential for ensuring the effective correspondence be-\ud tween the real and the declared identity of a clone, to avoid\ud commercial frauds, and to establish breeding programmes.\ud Molecular markers may play a major role to satisfy all these\ud needs

Développement de marqueurs microsatellites pour l’identification et la certification des clones commerciaux de peuplier en Espagne

“…The genotypic similarity between [I-214/Campeador] and [I-MC/NNDv] pairs of clones is also supported by the results obtained by Alvárez et al [1] using AFLP markers and the analogy between genotypes for [I-MC/BL-Costanzo] accessions described in Fossati et al [15] is also in agreement with our results. For the clone "Bordils" two clearly different genotypes (in eight out of ten loci) have been observed in the samples analysed.…”

“…The need to use molecular methods for the certification of plant material from vegetative propagation has been suggested by numerous institutions and research groups [1,3,15,29,40]. The European laws permit within the entire community the cultivation of poplar clones listed in the National Catalogue of any member country.…”

“…Ten nuclear microsatellite regions were selected considering genetic independence between markers and assuming the good synteny already described among Populus species [6]. Moreover, five of them are those used in the previous work of Fossati et al [15], which will allow us to compare the results obtained. The SSR loci used and corresponding linkage groups (LG) were the following: PTR2 (LG IX), PTR4 (LG III) [9] and PTR7 (LG XII) [27] developed for P. tremuloides; WPMS9 (LG VI), WPMS14 (LG V), WPMS16 (LG VII), WPMS18 (LG not found), WPMS20 (LG not found) developed for P. nigra [33,37]; PMGC14 (LG XIII) and ORPM127 (LG IV) developed for P. trichocarpa [36].…”

“…A great amount of useful information for genetic characterization and identification of poplars has accumulated, coming from the use of both allozyme polymorphism [28,30] or DNA markers: RAPDs [4,23,29,31] AFLPs, [1,6,8,15,40], microsatellites (SSRs) [3,6,10,14,30] and ISSRs [20].…”

“…As many of them have shown their usefulness on different poplar species or hybrids, it is advisable to use them for the molecular description of commercial poplars, most of which are interspecific hybrids [3,15,29,40].…”