Kimberly L Kanapeckas1, Te-Ming Tseng2, Cynthia C Vigueira3, Aida Ortiz4, William C Bridges5, Nilda R Burgos6, Albert J Fischer7, Amy Lawton-Rauh8. 1. South Carolina Department of Natural Resources Marine Resources Research Institute and College of Charleston, Hollings Marine Laboratory, Charleston, SC, USA. 2. Department of Plant and Soil Sciences, Mississippi State University, MS, USA. 3. Department of Biology, High Point University, High Point, NC, USA. 4. Facultad de Agronomía, Universidad Central de Venezuela Maracay, Aragua, Venezuela. 5. Department of Mathematical Sciences, Clemson University, Clemson, SC, USA. 6. Department of Crop, Soil, and Environmental Sciences, University of Arkansas, Fayetteville, AR, USA. 7. Department of Plant Sciences, University of California, Davis, CA, USA. 8. Department of Genetics and Biochemistry, Clemson University, Clemson, SC, USA.
Abstract
BACKGROUND: Weed evolution from crops involves changes in key traits, but it is unclear how genetic and phenotypic variation contribute to weed diversification and productivity. Weedy rice is a conspecific weed of rice (Oryza sativa) worldwide. We used principal component analysis and hierarchical clustering to understand how morphologically and evolutionarily distinct US weedy rice populations persist in rice fields in different locations under contrasting management regimes. Further, we used a representative subset of 15 sequence-tagged site fragments of expressed genes from global Oryza to assess genome-wide sequence variation among populations. RESULTS: Crop hull color and crop-overlapping maturity dates plus awns, seed (panicle) shattering (> 50%), pigmented pericarp and stature variation (30.2% of total phenotypic variance) characterize genetically less diverse California weedy rice. By contrast, wild-like hull color, seed shattering (> 50%) and stature differences (55.8% of total phenotypic variance) typify genetically diverse weedy rice ecotypes in Arkansas. CONCLUSION: Recent de-domestication of weedy species - such as in California weedy rice - can involve trait combinations indistinguishable from the crop. This underscores the need for strict seed certification with genetic monitoring and proactive field inspection to prevent proliferation of weedy plant types. In established populations, tillage practice may affect weed diversity and persistence over time.
BACKGROUND: Weed evolution from crops involves changes in key traits, but it is unclear how genetic and phenotypic variation contribute to weed diversification and productivity. Weedy rice is a conspecific weed of rice (Oryza sativa) worldwide. We used principal component analysis and hierarchical clustering to understand how morphologically and evolutionarily distinct US weedy rice populations persist in rice fields in different locations under contrasting management regimes. Further, we used a representative subset of 15 sequence-tagged site fragments of expressed genes from global Oryza to assess genome-wide sequence variation among populations. RESULTS: Crop hull color and crop-overlapping maturity dates plus awns, seed (panicle) shattering (> 50%), pigmented pericarp and stature variation (30.2% of total phenotypic variance) characterize genetically less diverse California weedy rice. By contrast, wild-like hull color, seed shattering (> 50%) and stature differences (55.8% of total phenotypic variance) typify genetically diverse weedy rice ecotypes in Arkansas. CONCLUSION: Recent de-domestication of weedy species - such as in California weedy rice - can involve trait combinations indistinguishable from the crop. This underscores the need for strict seed certification with genetic monitoring and proactive field inspection to prevent proliferation of weedy plant types. In established populations, tillage practice may affect weed diversity and persistence over time.