Genome of the world’s smallest flowering plant, Wolffia australiana, helps explain its specialized physiology and unique morphology

Watermeal, Wolffia australiana , is the smallest known flowering monocot and is rich in protein. Despite its great potential as a biotech crop, basic research on Wolffia is in its infancy. Here, we generated the reference genome of a species of watermeal, W. australiana , and identified the genome-wide features that may contribute to its atypical anatomy and physiology, including the absence of roots, adaxial stomata development, and anaerobic life as a turion. In addition, we found evidence of extensive genome rearrangements that may underpin the specialized aquatic lifestyle of watermeal. Analysis of the gene inventory of this intriguing species helps explain the distinct characteristics of W. australiana and its unique evolutionary trajectory. Halim Park and Jin Hwa Park et al. report the nuclear genome sequence of the duckweed Wolffia australiana , the smallest known flowering plant. The genome assembly represents an improvement over a recently published genome and highlights genome rearrangements that may be linked to its specialized aquatic adaptations.