ALBERT

Description: Miscanthus lutarioriparius is an endemic species that grows along the middle and lower reaches of the Yangtze River and is a valuable source of germplasm for the development of second-generation energy crops. The plant that propagates via seeds, stem nodes, and rhizomes shows high phenotypic variation and strong local adaptation. Here, we examined the magnitude and spatial distribution of genetic variation of M. lutarioriparius across its entire distributional range and tested underlying factors that shaped its genetic variation. Population genetic analyses were conducted on 644 individuals from 25 populations using 16 microsatellite markers. M. lutarioriparius exhibited a high level of genetic variation ( H E = 0.682-0.786; A r = 4.74-8.06) and a low differentiation ( F ST = 0.063; D est = 0.153). Of the total genetic variation, 10% was attributed to differences among populations ( d.f . = 24, P 〈 0.0001), whereas 90% was attributed to the differences among individuals ( d.f . = 619, P 〈= 0.0001). Genetic diversity did not differ significantly across longitudes and did not increase in the populations growing downstream of the Yangtze River. However, significant associations were found between genetic differentiation and spatial distance. Six genetic discontinuities were identified, which mostly distributed among downstream populations. We conclude that anthropogenic factors and landscape features both contributed to shaping the pattern of gene flow in M. lutarioriparius , including long-distance bidirectional dispersal. Our results explain the genetic basis of the high degree of adaptability in M. lutarioriparius and identify potential sources of new germplasm for the domestication of this potential second-generation energy crop. This article is protected by copyright. All rights reserved.