Morphological Variation and Genetic Patterns of Bermudagrass along Longitudinal and Latitudinal Gradients

概要

This complex environmental heterogeneity coupled with the long-standing history off ers scenarios suitable for and favoring the evolution and existence of variation of morphological traits. Understanding the population genetic pattern and process of gene flow requires a detailed knowledge of how landscape characteristics structure populations. Geographic patterns in morphological variation and ploidy level of 570 Cynodon dactylon (L.) Pers. (common bermudagrass) individuals sampled from 28 geographic sites along a latitudinal and longitudinal gradient across China were observed. Genetic diversity and structure within these collections was estimated via expressed sequence tag-derived simple sequence repeat (EST-SSR). Considerable variations in morphological traits were observed at diff erent longitudes and latitudes. Larger morphological sizes of C. dactylon appeared at the low and high-latitude regions, while the leaves of the erect shoot and the internode length enlarged signifi cantly with the collection sites moving from east to west. Higher within-population genetic diversity appeared at low-latitude, as well as having positive correlation with temperature and precipitation. No isolation by distance and notable admixture structure existed among populations along latitudes, but low gene fl ow means a rich genetic diff erentiation among populations of C. dactylon along longitudinal gradient. The genetic diversity increased with the ploidy level of C. dactylon at diff erent latitudes, suggesting polyploidy creates higher genetic diversity. Groups of individuals with the same ploidy at diff erent longitudes were separated further away by genetic distance along with the increasing ploidy levels. The fi ndings of this study are related to landscape population evolution, polyploidy speciation, preservation, and use of bermudagrass breeding.

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