SEARCHING FOR SUSTAINABLE ENERGY,
by The Editors
First, researchers have stated that Miscanthus (M. x giganteus) was sterile because it was allopolyploid, but that allopolyploidy does not guarantee continued sterility. It has never to our knowledge been claimed that allopolyploidy confers sterility. Miscanthus is sterile because it is triploid, a cross between two species where one has double the chromosome number of the other. As a result the hybrid has three sets of chromosomes instead of the normal two. This prevents the normal pairing of chromosomes needed to form fertile pollen and ovules. In such plants, there is a remote possibility that a fertile pollen grain and ovule could result by random change, but given the number of chromosomes in Miscanthus, that probability is 4 in 100 quadrillion, and this assumes that the fertile pollen grain actually finds the fertile ovule. Even if this rare event occurred, Miscanthus is self-infertile. Since the plant is clonally propagated, even this exceptionally rare event is precluded. Triploid technology has been used in the production of seedless fruits such as bananas, tomatoes, and watermelons for many decades without failure.
Secondly, Miscanthus has been grown in the European Union for over 20 years, with trials across the EU begun in the early 1980s and commercial plantations starting in the 1990s. Yet across a wide range of latitudes, soil types, and topographies there has been no evidence of any invasive risk.
Finally and most significantly, the very similar and productive fertile parent of M. x giganteus, M. sinensis, is available from most nurseries across the United States and has been for decades. It can be seen commonly in gardens throughout Illinois and much of the United States. If there is an invasive risk from Miscanthus, then a warning is a few decades too late. And if there is a risk, it has been taken by the horticulture industry in providing the fertile parent and not by the agricultural industry that is proposing to use the sterile hybrid.
In dealing with global change, society faces stark choices. “Business as usual” means significant rises in temperatures that will expand the habitat of known invasive species. Perennial grass bioenergy crops seemingly provide a major opportunity for slowing change globally, while minimizing environmental impacts. Some researchers imply that we should not be considering plants that are highly productive, perennial, and with low fertilizer- and pesticide-use requirements since these are an invasive risk. This logically implies that their acceptable alternative will be less productive annuals requiring large fertilizer and pesticide inputs, and the conversion of more land to agriculture because of their low productivity. These properties in themselves have well-known detrimental effects on biodiversity in the wider context. No technology can be said to be 100% risk free, and vigilant monitoring of new crops is critical. However, in annual monitoring stands in Europe that are up to 30 years old and stands in Illinois that are 16 years old, there has been no evidence of any spread, either by rhizomes or seedlings.
Stephen P. Long is Robert Emerson Professor in the Departments of Plant Biology and Crop Sciences at the University of Illinois at Urbana-Champaign. Frank Dohleman is a graduate student in the Department of Plant Biology at the University of Illinois at Urbana-Champaign. Other authors and their affiliations include Professor Michael B. Jones, Trinity College, University of Dublin, Ireland; John Clifton-Brown, Institute for Grassland and Environmental Research, Aberystwyth, Wales; and Uffe Jørgensen, Department of Agroecology, Danmarks JordbrugsForskning, Foulum, Denmark.
