Plant 256

Miscanthus sinensis Andersson (Poaceae)

Chinese silver grass

Miscanthus is a small genus of perennial grasses whose disjunct distribution extends from South Africa, through southern and eastern Africa, and then jumps to the Himalayas, East Asia and Polynesia. Miscanthus is one of the genera in the Andropogoneae, a tribe that also includes economically important grasses such as sugarcane, sorghum and maize.

In Europe, Miscanthus sinensis is best known as a large, clump-forming ornamental that comes into its own in the autumn. In North America, Miscanthus giganteus (a hybrid between Miscanthus sinensis and Miscanthus sacchariflorus) has gained prominence as a possible renewable energy source.

Photosynthesis is mediated through the 'Jekyll and Hyde' enzyme Ribulose bisphosphate carboxylase oxygenase (RuBisCo). As Jekyll, RuBisCO adds carbon dioxide to a sugar containing five carbon atoms to produce two three-carbon molecules, which eventually produces sugars and starch. This is C3 photosynthesis and is typical of plants from tropical or temperate areas with access to moderate amounts of water, sunlight and carbon dioxide.

However, as temperatures or water stresses increase, the Hyde-side of RuBisCO emerges. Instead of adding more carbon dioxide to the five-carbon sugar, oxygen is added, reducing the efficiency of photosynthesis. To overcome these disadvantages, some plants have evolved a biochemical carbon pump at the start of C3 photosynthesis that keeps carbon dioxide levels high. This process is C4 photosynthesis. At night, in special cells called bundle sheath cells, carbon dioxide is converted to molecules containing four carbon atoms. During the day, these compounds are transported into other cells where carbon dioxide is released and C3 photosynthesis takes place.

Miscanthus giganteus has attracted considerable attention in Europe and North America as a potential new crop plant for biofuel production because of its C4 photosynthesis, combined with its low nutrient requirements, high water-use efficiency and high yields across different environments and temperate climates. However, only one sterile clone, imported to Europe from Japan in the 1930s, is commonly used.

Because of the potentially devastating consequences of disease, breeding Miscanthus giganteus as a novel crop based a narrow genetic base is risky. Such concerns have driven interest in artificial resynthesis of the hybrid based on understanding genetic variation in the parental species.

In its native range, Miscanthus sinensis has high genetic variation in three geographic regions, Korea, Japan and China. Moreover, many familiar cultivars of Miscanthus sinensis are hybrids with Miscanthus sacchariflorus, whilst naturalised populations of Miscanthus sinensis in North America come from southern Japan.

Further reading

Clark LV et al. 2014. A footprint of past climate change on the diversity and population structure of Miscanthus sinensis. Annals of Botany 114: 97-107.

Quinn LD et al. 2010. Invasiveness potential of Miscanthus sinensis: implications for bioenergy production in the United States. Global Change Biology Bioenergy 2: 310-320.

Stewart JR et al. 2009. The ecology and agronomy of Miscanthus sinensis, a species important to bioenergy crop development, in its native range in Japan: a review. Global Change Biology Bioenergy 1: 126-153.

Stephen Harris