Crop Ferality and Volunteerism
Crop Ferality and VolunteerismJB. Gressel ed. 2005.
Boca Raton, Florida: CRC Press. Price £97 (hardback). 422 pp.
Volunteers and weedy crop (feral) plants have been with us ever since the domestication of crops. Whilst we know a great deal about their biology and management as weeds, little scientific attention has been paid to their evolution, and understanding their role in the domestication and de-domestication of crops. With the commercialization of transgenic crops, there is a greater urgency to understand these processes and establish whether volunteer (crop plants that germinate in subsequent years after a crop has been harvested) and feral (plants derived in full or in part from crop plants that have become fully or partially de-domesticated) populations pose a threat to the food chain. In some crop species our limited knowledge of these processes can have economic consequences. In Europe, for example, Austria has banned the import of GT73 transgenic oilseed rape partly over concerns that feral oilseed rape establishes and persists along transport routes to processing plants. These concerns extend to the possibility that feral rape can acquire novel genes and disseminate them to commercial oilseed rape and other Brassica species. The publication of this book is, therefore, timely as it attempts to address the knowledge gap surrounding the impacts and consequences of ferality.
The book evolved from an OECD-sponsored workshop in 2004 on ‘Crop Ferality and Volunteerism: A Threat to Food Security in the Transgenic Era’ held in Bellagio, Italy. Under the editorship of Jonathan Gressel, the participants, and a small group of invited experts, have contributed a series of peer-reviewed articles and research papers to explore volunteerism (as it is the primary step that leads to ferality) and ferality in a broad range of the world's important food crops. It is the first book on this subject and provides a wealth of valuable information on crop and weed science, plant molecular biology and genetics that relates to volunteer and feral plants. The articles are extensively referenced and are illustrated by black and white diagrams, graphs and photographs. The book is very informative and deserves our attention.
The first two chapters set the scene by introducing the biodiversity of feral forms, reviewing the differences among domesticated crops, agricultural weeds and feral plants, and describing their interactions within the domestication and de-domestication process, placing a particular emphasis on the genetics of domestication and weediness traits. This is followed by a chapter on the ecology and detection of ferality using historical records and archeobotanical methods. The next 18 chapters discuss the variety of feral forms within specific crops. They cover beet, oilseed rape, foxtail millet, urban ornamentals, sorghum, soyabean, maize, wheat, rye, radish, sunflower and other Helianthus species, oat, olive, the Vigna group, ryegrass, safflower, sugarcane and rice. For the most part each crop is considered according to its evolution; the extent to which crop, weed and wild relative complexes are formed; how the various components interact with one another; and the influence of crop management practices. The impact of novel traits (mainly herbicide and insect resistance) upon ferality is also discussed where crop varieties have been commercialized. There are five chapters on rice, which illustrate the impact that feral rice has upon crop management practices in different geographical regions across the world. The book concludes with chapters on biological containment as a means of preventing gene establishment in volunteers and ferals; approaches towards environmental risk assessment; and an epilogue that emphasizes the importance of good agricultural practice in reducing the impact of volunteer and feral plants.
The value of this book lies in demonstrating the complexity and differences in the factors that cause ferality. They can vary according to the degree of domestication in a crop; the number of genes underlying weedy traits; the frequency and occurrence of sexually compatible neighbouring weeds and wild relatives; the effects of different agronomic practices worldwide; and movement of crop seed through international trade. As shown by oilseed rape, rye and rice, the extent to which the factors interact depends upon geographical area and cultural practices. Every crop–weedy–wild complex has its own nuances and differences showing that there is no unified theory of ferality. The diversity of these different systems justifies the large number of case studies and the crop-by-crop format set out in the book. From this perspective, the book serves as a valuable reference for studying and comparing these processes.
The impact of transgenic agriculture upon these complexes is covered in detail in only a few of the chapters. This is understandable as only a third of the crops discussed in the book have transgenic varieties that are cultivated commercially. Of these, soyabean and maize are the only two transgenic crops that are grown worldwide. Whilst most authors attempt to discuss the potential impact of novel genes residing in feral populations, there is a lack of data to support their predictions. Unless more empirical data are available on the population dynamics of feral populations and out-crossing rates back to crop plants, it is difficult to fully predict whether the produce of field crops will be devalued by feral populations acting as a source of novel genes.
The book will be a useful primer for undergraduates, post-graduates, researchers and regulators who wish to study the interactions between crops, ferals and wild relatives. It will also assist their understanding of the processes that underpin crop domestication and de-domestication. I hope the book will also stimulate researchers to investigate the contribution of gene flow to the dynamics of feral populations in a wide range crop of plants.
E-mail: jonathan.davey{at}sasa.gsi.gov.uk
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