Telling duckweed apart: genotyping technologies for the Lemnaceae

The family of Lemnaceae, commonly called duckweed, comprise five genera and 37 species of aquatic monocotyledonous plants that are endemic to lakes, ponds and brackish water bodies on most continents. They are angiosperms that have the highest biomass production rate and have been used to remediate wastewater from both municipal and industrial sources. With these attractive features, duckweed is poised to be a novel agricultural platform that can complement current terrestrial crops. In addition, their remarkable ability to adapt to diverse climates and conditions may provide new understanding of stress tolerance and genome adaptability mechanisms. However, one of the first challenges facing these applications is to establish reliable and rapid methods for identification of closely related strains that may have very different behaviour or properties. This review article summarizes the state of the arts for this endeavour and provides the outlook for this quest in the near future. Fig 2, Tab 2, Ref 53Klaus J. Appenroth, Nikolai Borisjuk, Eric La

The <em>Spirodela polyrhiza</em> genome reveals insights into its neotenous reduction fast growth and aquatic lifestyle.

The subfamily of the Lemnoideae belongs to a different order than other monocotyledonous species that have been sequenced and comprises aquatic plants that grow rapidly on the water surface. Here we select Spirodela polyrhiza for whole-genome sequencing. We show that Spirodela has a genome with no signs of recent retrotranspositions but signatures of two ancient whole-genome duplications, possibly 95 million years ago (mya), older than those in Arabidopsis and rice. Its genome has only 19,623 predicted protein-coding genes, which is 28% less than the dicotyledonous Arabidopsis thaliana and 50% less than monocotyledonous rice. We propose that at least in part, the neotenous reduction of these aquatic plants is based on readjusted copy numbers of promoters and repressors of the juvenile-to-adult transition. The Spirodela genome, along with its unique biology and physiology, will stimulate new insights into environmental adaptation, ecology, evolution and plant development, and will be instrumental for future bioenergy applications