Date Published: May 24, 2019
Publisher: Public Library of Science
Author(s): Annika Wieghaus, Dirk Prüfer, Christian Schulze Gronover, David A. Lightfoot.
The Russian dandelion (Taraxacum koksaghyz) is a promising source of inulin and natural rubber because large amounts of both feedstocks can be extracted from its roots. However, the domestication of T. koksaghyz requires the development of stable agronomic traits such as higher yields of inulin and natural rubber, a higher root biomass, and an agronomically preferable root morphology which is more suitable for cultivation and harvesting. Arabidopsis thaliana Rapid Alkalinisation Factor 1 (RALF1) has been shown to suppress root growth. We identified the T. koksaghyz orthologue TkRALF-like 1 and knocked out the corresponding gene (TkRALFL1) using the CRISPR/Cas9 system to determine its impact on root morphology, biomass, and inulin and natural rubber yields. The TkRALFL1 knockout lines more frequently developed a taproot phenotype which is easier to cultivate and harvest, as well as a higher root biomass and greater yields of both inulin and natural rubber. The TkRALFL1 gene could therefore be suitable as a genetic marker to support the breeding of profitable new dandelion varieties with improved agronomic traits. To our knowledge, this is the first study addressing the root system of T. koksaghyz to enhance the agronomic performance.
The Russian dandelion (Taraxacum koksaghyz) is a sexually reproducing, self-incompatible, perennial plant species in the family Asteraceae , renowned for its rapid growth and climatic versatility. T. koksaghyz has recently emerged as a promising industrial feedstock for temperate regions because of its ability to produce and store significant amounts of natural rubber and inulin in its roots, although complete domestication is required before it can be adopted as an industrial crop [2,3].
T. koksaghyz accumulates considerable quantities of valuable metabolites such as inulin and natural rubber in its roots, and is therefore considered as a promising alternative source of both feedstocks [6,11,36]. However, most previous studies have focused on the inulin and natural rubber metabolic pathways [37–41], rather than the root morphology. In this study, for the first time, we addressed the morphology, growth and productivity of T. koksaghyz roots by investigating the impact of TkRALFL1, a member of the RALFL peptide family.