Unraveling the evolutionary dynamics of ancient and recent polyploidization events in Avena (Poaceae).
Understanding the diversification of polyploid crops in the circum-Mediterranean region is a challenging issue in evolutionary biology. Sequence data of three nuclear genes and three plastid DNA fragments from 109 accessions of Avena L. (Poaceae) and the outgroups were used for maximum likelihood and Bayesian analyses. The evolution of cultivated oat (Avena sativa L.) and its close relatives was inferred to have involved ancient allotetraploidy and subsequent recent allohexaploidy events. The crown ages of two infrageneric lineages (Avena sect. Ventricosa Baum ex Romero-Zarco and Avena sect. Avena) were estimated to be in the early to middle Miocene, and the A. sativa lineages were dated to the late Miocene to Pliocene. These periods coincided with the mild seasonal climatic contrasts and the Mediterranean climate established in the Mediterranean Basin. Our results suggest that polyploidy, lineage divergence, and complex reticulate evolution have occurred in Avena, exemplifying the long-term persistence of tetraploids and the multiple origins of hexaploids related to paleoclimatic oscillations during the Miocene-Pliocene interval in the circum-Mediterranean region. This newly-resolved infrageneric phylogenetic framework represents a major step forward in understanding the origin of the cultivated oat.
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.
Qing
Q
Liu
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
Lei
L
Lin
Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650, China.|University of Chinese Academy of Sciences, Beijing 100049, China.
Xiangying
X
Zhou
Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-7012, USA.
Paul M
PM
Peterson
Department of Botany, National Museum of Natural History, Smithsonian Institution, Washington, DC 20013-7012, USA.
Jun
J
Wen
D018554:Avena / Q000235:genetics*; D019143:Evolution, Molecular; D011123:Polyploidy