Gene switch makes sweet sorghum salt-tolerant, researchers found

In Germany, the Karlsruhe Institute of Technology (KIT) noted that sorghum millet is seen as the crop plant of the future as it builds up a particularly high amount of biomass and thrives in harsh conditions. In an in-depth investigation of this salt-stress-induced sugar accumulation conducted by an international team including scientists from KIT it was found that the SWEET13 gene switch is responsible for directing sugar into the grains.

The Molecular Cell Biology Division workgroup, headed by Professor Peter Nick at KIT’s Joseph Gottlieb Kölreuter Institute for Plant Sciences (JKIP), has been working for some years on sorghum millet, which belongs to the millet species in the sweet grass family. The sorghum varieties rich in sugar are called sweet sorghum. Sorghum millet is one of the crops with a particularly efficient photosynthesis process, which have a higher capacity to sequester carbon dioxide (CO2) and build up more biomass than other plants. Previous research of Syrian scientist Adnan Kanbar at KIT resulted in the development of a new sweet sorghum variety that accumulates a particular large amount of sugar and is well suited for producing biogas and biofuels and for producing new polymers.

Further research shows that sorghum millet, an ancient crop plant from Sudan, thrives even in harsh conditions. “Certain sorghum millet varieties not only cope well in a saline environment, but react to increased salinity with the production of even more sugar,” said Peter Nick. “Some of these varieties store the sugar in the stem, which makes them a candidate for energetic use, i.e. the production of biofuels. Other varieties store the sugar in the seeds, making them a valuable contribution to human nutrition.”

This salt stress-induced sugar accumulation and the different ways to store sugar in the plant was investigated by a group of researchers led by Eman Abuslima from Egypt, who completed her doctorate at the Molecular Cell Biology Division workgroup of KIT’s JKIP institute. They discovered that the SWEET13 gene is responsible for sugar transport. “SWEET13 works like a switch: It determines that the sucrose formed by photosynthesis is directed into the plant’s grains,” explains Abuslima.

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