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Abstract Detail

Symposium: Speaking of Food: connecting basic and applied science

Caicedo, Ana [1].

How to create an agricultural weed: convergent evolution and the origin of weedy red rice populations.

Agricultural weeds are among the greatest crop pests, leading to worldwide reductions in crop productivity and billions of dollars in crop losses each year. Though taxonomically diverse, agricultural weeds are often highly competitive plants that have adapted to evade human removal from crop fields. In this context, agricultural weeds have repeatedly been selected for weed-adaptive traits such as rapid growth, increased seed dispersal and dormancy, thus providing an ideal system for the study of convergent evolution. Weedy red rice (Oryza sativa), a conspecific obligate weed of cultivated rice, infests rice fields worldwide, and is believed to have multiple evolutionary origins. In the US, two main weedy rice populations coexist, each with a separate origin from distinct cultivated ancestors. We are assessing the extent of convergent evolution at the genetic and phenotypic level in the two US weedy rice populations using traditional genetic and genomic approaches. While convergence is evident for some weedy traits, such as seed shattering, other traits are divergent between the two weed groups. Using crop x weed crosses, we have mapped QTL for four quantitative traits differentiating weedy groups from cultivated rice. Most QTL locations do not overlap between the two populations, suggesting that different genes underlie weed-adaptive traits in each group. Genome scans of highly diverged genes between each weed and its cultivated ancestor also suggest limited sharing of “weedy” genes among red rice populations. However, sharing of some genes involved in energy metabolism may indicate convergent genetic evolution for competitiveness traits in weedy rice. Our results suggest that, despite a close evolutionary relationship, US weedy rice groups have adapted to the same agricultural environment largely through different genetic mechanisms. The evolution of US weedy rice groups within the context of worldwide weedy rice populations is discussed.

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1 - University of Massachusetts, 221 Morrill Science Center, 611 North Pleasant St., Amherst, MA, 01003, USA

Oryza sativa
seed shattering
quantitative trati loci
parallel evolution
weed evolution

Presentation Type: Symposium or Colloquium Presentation
Session: SY06
Location: Grand Ballroom A/Riverside Hilton
Date: Tuesday, July 30th, 2013
Time: 11:00 AM
Number: SY06006
Abstract ID:245
Candidate for Awards:None

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