SSCP polymorphisms of gene introns and morphological traits: novel procedures for clonal identification in poplar

Conventional clonal identification system, based on combination of morphological and phenological traits, represents a difficult, ambiguous, time consuming and subjective method. Considering the importance of varietal identification in poplar and the necessity to have certificated material to trade, the aim of this work is to develop new molecular markers simple and inexpensive for clonal identification for the breeding and genetic resource management programs. We developed SSCP (single-strand conformational polymorphism) markers for two poplar catalase genes of P. deltoides (Cat1 and Cat2) by designing specific primers flanking introns. Four primer pairs have been selected: two primer pairs (Cat1-A and Cat1-B markers) have been designed based on Cat1 gene coding sequence spanning intron II and introns V-VI-VII respectively. Two other primer pairs (Cat2-C and Cat2-D markers) have been designed based on Cat2 gene coding sequence spanning introns II-III and IV-V respectively. In this study, the suitability of developed SSCP markers have been tested by differentiating 96 poplar commercially important clones belonging to P. alba, P. deltoides, P. nigra, P. trichocarpa species and largely to P. x canadensis. The results emphasized that SSCP analysis was efficient to detect DNA polymorphism. It is a sensitive analytical tool for interspecific and intraspecific identification