The Miscanthus sacchariflorus homeland lies beneath the waves

Miscanthus × giganteus is a popular hybrid for biofuels. It’s a hybrid of M. sinesis and M. sacchariflorus. A lot of research has focussed on M. sinesis but Lindsay Clark and colleagues argue, in the Annals of Botany, that M. sacchariflorus has the greater potential for improvement from genetic diversity. “The tetraploid M. sacchariflorus parent not only contributes two-thirds of the genetic material of triploid M. × giganteus, but is also thought to make a large contribution to its high yield via chilling-tolerant photosynthesis, which effectively extends its growing season.”

M. sacchariflorus grows in quite a lot of East Asia, in China, Korea, Japan and eastern Russia, from 28 to 50 °N and from sea level to 2000m elevation. “Especially noteworthy is that M. sacchariflorus probably has the greatest winter hardiness among all the Saccharinae, with populations from northern China and eastern Russia adapted to an average annual minimum air temperature of –40.0 °C (USDA hardiness zone 3),” said the authors in their paper.

To uncover the genetic diversity of the plant, the team collected Miscanthus from sites in Russia, China, South Korea and Japan. They then looked at the genetic diversity of the populations.

The results they gathered suggested the most genetically diverse region had been lost to sea level rise since the last glacial maximum. “Multiple lines of evidence indicate that current populations of M. sacchariflorus were derived from an ancestral population that refuged during the last glacial maximum (LGM) on land that is now under the Yellow Sea and East China Sea. Perhaps most compelling is the observation that the four most genetically diverse extant M. sacchariflorus groups currently inhabit land surrounding these seas, whereas derived sub-groups are found more distant, indicating a radiation from this region.”

“During the LGM, the climate of East Asia was too cold and dry to support populations of M. sacchariflorus throughout much of its current range, but the environment in the southern Yellow Sea Basin would have been favourable.”

“[D]uring the LGM, a steppe-dominated ecosystem covered a wide area from the present day Korean Peninsula in the east to the mountains surrounding the Sichuan Basin in the west, including all of the Yellow Sea Basin and the north-western edge of the East China Sea Basin… Moreover, the two largest rivers in East Asia, the Yellow River and the Yangtze River, flowed over the southern portion of the Yellow Sea Basin during the LGM.”

Getting a better understanding of the genetic diversity of M. sacchariflorus could have real benefits, say the authors. “Given that M. sacchariflorus also has substantially more genetic diversity than M. sinesis, we expect that selection within M. sacchariflorus will provide the greatest opportunity to make genetic gains for breeding improved M. × giganteus.”