Indirect Estimation of Genetic Structure and Gene Flow in Some Black Poplar (Populus Nigra) Clones using Leaf Morphophysiological Traits

Extensive application of imported poplar clones, can lead to destruction of genetic resources. Determination of intensity and direction of gene flow between population origin, provided important information in order to orienting the improvement and conservation programs. In between, introducing some reliable morphological traits, those are important in clonal differentiation, could accelerate this process considering lower costs in compare with molecular markers.

In present study five clones of black poplar (Populus nigra) in order to investigating the feasibility of clonal differentiation and estimating genetic parameteres like genetic distance and gene flow by means of morphological markers were planted in a complete randomized block design by three replications in selection nursery of Yasouj university and leaf morphological traits of one-year-old saplings were investigated. Morphological traits related with leaf blade, dentation and lobe, vein, petiole, and tip and base shape of leaf was measured in late fall, and the feasibility of clonal differentiation using discriminant functions analysis and cluster analysis was investigated. Finally, by means of an integrating approach consists of predicting models of discriminant functions and cluster analysis of phylogenetic relations, genetic distance, and intensity and direction of gene flow between clones were discussed and investigated.

The results of discriminant analysis revealed that leaf fresh weight, leaf virtual and actual aspect ratio, by 65 percent accuracy, had the highest effects in clonal differentiation of poplar clones. Among the investigated black poplar clones, the Irannian native clone with its small and narrow leavs was distincted from the Turkish native clone, and other clones were in the middle. These variations were in accordance with the geographical location and climatic conditions of these clones. The native and breeded Iranian clones had the lowest and highest amount of plasticity, respectively. Examination of the genetic structure of the clones showed that there was no significant gene flow between most of the studied clones, but significant gene flow was observed between the anonymous native Turkish clone and breeded Iranian clones, and the direction of this flow was more from the Turkish to Iranian clone.

In conclusion, in general, there were few signs of hybrid swarm between Iranian native poplar with the other studied cultivars, but the widespread use of the improved Iranian poplar cultivars increases the need to pay attention to the protection of native genetic resources.