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ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Emerging Pests and Pathogens Research » Research » Publications at this Location » Publication #331197

Research Project: Evaluation of Biological Control for Invasive Weeds of the Northeastern United States

Location: Emerging Pests and Pathogens Research

Title: Genome size and invasiveness traits in the hybrid meadow knapweed complex (Centaurea x moncktonii) in eastern North America

item KELLER, STEPHEN - University Of Vermont
item MOLOFSKY, JANE - University Of Vermont
item PALACIO-LOPEZ, KATTIA - University Of Vermont
item SUDA, JAN - Academy Of Sciences Of The Czech Republic (ASCR)
item Milbrath, Lindsey

Submitted to: NeoBiota
Publication Type: Proceedings
Publication Acceptance Date: 5/2/2016
Publication Date: 9/13/2016
Citation: Keller, S., Molofsky, J., Palacio-Lopez, K., Suda, J., Milbrath, L.R. 2016. Genome size and invasiveness traits in the hybrid meadow knapweed complex (Centaurea x moncktonii) in eastern North America. NeoBiota. Book of Abstracts, Neobiota 2016-9th International Conference on Biological Invasions. p. 192.

Interpretive Summary:

Technical Abstract: Hybridization and genomic admixture between divergent populations or species may be an important driver of plant invasiveness. Recent studies have emphasized the critical role that reductions in genome size may play in facilitating the rapid evolution of invasiveness, and small genome size has been associated in some plant invaders with increased competitive ability and reproductive effort. Here, we report on genome size and trait variation in a hybrid complex of knapweeds (genus Centaurea) invasive in eastern North America. The hybridizing swarm consists of extensive introgression between brown knapweed (C. jacea), black knapweed (C. nigra) and their hybrid (C. x moncktonii). Previous studies of this complex in Europe have reported both diploid (2n = 22) and tetraploid (2n=44) cytotypes, with extensive genome size polymorphism observed among populations. We sampled seed from 10 maternal plants from each of 20 populations located across two regions (New York and Vermont). Six seed offspring per maternal family were germinated and grown in a greenhouse to maturity. Individuals were measured for traits associated with invasiveness based on vegetative size and competitive ability (maximum height, specific leaf area, total biomass) and reproductive effort (time to flowering, flower and capitula number). Leaf tissue was sampled from a subset of 2-4 offspring per family for genome size analysis by flow cytometry. The mean 1C value of genome size was 1.92 pg, with a coefficient of variation of 2.2%, consistent with the presence of exclusively tetraploid cytotypes in our sample. There was significant geographic structure to genome size at both the among-region (p=0.01) and among-population (p<0.0001) scales. Invasiveness traits also varied among populations; however, we observed no association between genome size and trait variation. The results suggest significant variability in this invasive hybrid swarm for genome size, probably arising from non-homologous crossing over among introduced tetraploid cytotypes, but this variation does not translate directly into differences in functional traits predictive of plant invasiveness.