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Department of Horticulture and Crop Science


HCS Seminar Series Spring 2015

Mar 4, 2015, 11:30am - 12:25pm

Ana Caicedo, Associate Professor

Department of Biology

221 Morrill Science Center
611 North Pleasant Street
University of Massachusetts-Amherst
Amherst, MA  01003

Phone 413-545-0975




Crop contributions to weed evolution: adaptation and convergence in weedy rice

ABSTRACT:  Agricultural weeds are one of the largest constraints on crop productivity, due, in part, to their intrinsic capacity for adaptation.
Weeds often undergo selection for traits such as rapid growth, increased seed dispersal, seed dormancy, and herbicide resistance, which may help them adapt to the agricultural environment. Weedy red rice (Oryza spp.) is a conspecific weed of cultivated rice that infests rice fields worldwide. Studies characterizing genomic patterns of polymorphism indicate that weedy rice has evolved multiple times from different ancestral backgrounds, including cultivated and wild rice groups. To understand the mechanisms by which agricultural weeds can evolve, we are assessing the extent of convergent evolution at the genetic and phenotypic level in populations of weedy rice. Seed shattering, a mechanism that aids in seed dispersal, seems the most broadly convergent trait across weedy rice groups. However, QTL mapping with crop x weed crosses suggest that independent genetic mechanisms underlie the shattering trait in different weed populations. Comparative genome scans of selected weeds and their crop ancestors support limited genetic convergence among weedy rice types. Weedy rice population structure can change very rapidly under human imposed selective pressures, such as under the recent large-scale implementation of herbicide resistant rice varieties in cultivated fields. These rapid changes challenge efforts to understand the genetic changes that are essential to the evolution of weediness.

11:30 AM - 12:25 PM
Kottman 244 (Columbus)
video-linked to
121 Fisher Auditorium (Wooster)