Miscanthus (a closely related species to sugar cane) denotes a herbaceous genus of plants, originating from South Asia and present in Africa too. This genus belongs to the Poaceae family (or Grasses). It is a long-lasting plant, with rhizomes and a very effective C4 photosynthetic metabolism. This property endows it an important potential for production of biomass. Some species, like Miscanthus sinensis, are moreover recognized as invasive plants. This specie is also called in South Asia « elephant grass ».&[ 2]
Miscanthus is planted during Spring (in March-April) and develops all summer long, until September. It produces stalks which can reach 4 meters high. According to the considered use, Miscanthus can be harvested in Autumn (green harvesting) or at the end of Winter (dry harvesting). A harvest of stalks can be realized, from the same Miscanthus plant every year, as the same plant can be cultivated during 15 years on average. An important asset is that rhizomes cover almost whole surface of the soil. It allows avoiding treatments against adventitious, as soon as the year following the installation of a new culture. It is a very resistant plant, with only very few diseases or pests identified until now.&
Miscanthus giganteus is a hybrid species, created by man, by crossing two different species: M. sinensis and M. sacchariflorus. This hybrid is sterile, but very productive in terms of biomass, with high contents of lignocellulose. As a consequence, the industry is highly interested in this plant species for applications such as the production of agro-fuels or in the field of green chemistry, as well for the production of biofuels, bioplastics…
However this productivity is strongly reduced for many Miscanthus species, because of their high sensitivity to low temperatures (below 10°C = 50°F). These temperatures are common in our Northern territories, where it is thus difficult to cultivate this plant. Therefore, research works were performed to study the behaviour of various Miscanthus genotypes in response to chilling. The main objective was to characterize the genetic basis of such a response. The expected results should help in selecting highly productive Miscanthus genotypes, even under environmental conditions with large variations of temperature (such as in our countries).
This study, with open access from Annals of Botany, has focused on the relationships between the intensity of photosynthesis, the carbohydrate content and the expression of different genes during the response of the plant to a sudden exposure to low temperatures.
The authors demonstrated that Miscanthus giganteus was the most productive species for photosynthesis, and that its two parental species displayed different behaviours under optimal conditions of culture. With regards to the accumulation of carbohydrates, M. sacchariflorus behaved like sugarcane (a demanding tropical plant in heat and humidity), whereas M. sinensis seemed closer to a grass of temperate regions. In response to chilling, M. giganteus was able to maintain more efficiently its production performances than the other species studied. The concentrations of two enzymes implied in the accumulation of sucroses decrease significantly in the least resistant genotypes; these proteins may thus play a role in the resistance against low temperatures. Besides, the transcription factor MsCBF3 was clearly more expressed in the genotypes which were sensitive to temperature variations. As a consequence, this gene could be a good molecular marker to be used in predicting the resistance to chilling for different Miscanthus genotypes.
These recently published results should open new leads of exploration with the aim of a genetic improvement of Miscanthus for its resistance to the low temperatures of our Northern regions. Maybe we will see elephant grass in France in a near future, but probably still without the herds of elephants…
Photo 1 : Miscanthus growing at the Great Lakes Bioenergy Research Center by theGreat Lakes Bioenergy Research Center. [cc]by-nc-sa[/cc]
-  Cultivons l’énergie de demain avec Miscanthus, France Miscanthus http://www.cgb-france.fr/IMG/pdf/Brochure_miscanthus_2009.pdf
-  Wikipédia, Miscanthus, http://en.wikipedia.org/wiki/Miscanthus, and you can see specifically Miscanthus giganteus and Miscanthus sinensis
-  Purdy S., Maddison A., Jones L., Webster R., Andralojc J., Donnison I., Clifton-Brown J., Characterization of chilling- shock responses in four genotypes of Miscanthus reveals the superior tolerance of M. x giganteus compared with M. sinensis and M. sacchariflorus. Annals of Botany 111 (5): 999-1013. DOI: 10.1093/aob/mct059