GENETIC DIVERSITY AND POPULATION STRUCTURE OF POPULUS YUNNANENSIS REVEALED BY SSR MARKERS

Populus yunnanensis, a native poplar in southwest China, is a potential candidate to improve the quality of poplars due to its high growth rate, wide adaptability, and strong disease-resistant ability. However, the genetic structure of P. yunnanensis has not been determined. To illustrate the genetic diversity and population structure of P. yunnanensis, 6 SSR markers, amplified from 208 specimens of 7 populations, were used in this study. In total, 35 alleles with a mean of 6 were acquired, and the genetic diversity was at a moderate level. Populations from Qujing (QJ) and Dali (DL) showed abundant genetic diversities, whereas the population from Lijiang (II) had low genetic diversities due to a relatively recent population bottleneck. Both Fstatistics and AMOVA results supported that the main genetic variation was attributed to individual differences within populations, and a high frequency gene flow (Nm = 5.560) occurred among populations. There was an overall increasing trend of genetic differences within populations from north to south and from east to west. Based on UPGMA, PCoA, and Bayesian analyses, populations from LJ, Liangshan (LS), QJ, and Zhaotong (ZT) were closely related to each other. A high barrier was found between the Kunming (KM) population and the Chuxiong (CX) population, and there was no correlated relationship (R = -0.159, P = 0.175) for the genetic and geographic distances between these two populations. We concluded that human activity was the decisive factor for shaping the present population distribution. Many potential resource types disappear at a fast rate, and the germplasm protection and scientific plan is imperative for breeding Populus and its genetic improvement.