ARF19 affects seed size in biofuel plant jatropha

Jatropha curcas is a perennial woody plant with high seed oil content that has potential to be used in biofuel production.  However, there is limited knowledge about the biology of seed oil production in Jatropha spp.  Sun. et al., used a genetic approach to identify a J. curcas QTL that controls seed length and contains the JcARF19 transcription factor.  The authors used quantitative real-time PCR to show JcARF19 expression is highest in the endosperm tissue.  Overexpression of JcARF19 in A. thaliana increased both seed length and dry seed weight.  Similar overexpression of JcARF19 in J. curcas increased beneficial agronomic traits, including flowering time, number of seeds per plant, seed weight, and seed length.  J. curcas overexpressing JcARF19 also shows higher expression of auxin-responsive genes including JcLBD18, JcLBD29, and JcCYCD2.  ARF transcription factors are inactivated by forming dimers with IAA proteins, and, JcARF19 interacted in vitro with JcIAA9.  Interestingly, JcIAA9 had a significantly weaker interaction with the ARF19 protein from the related J. integerrima.  The authors have described J. curcas auxin signaling as a step towards engineering the plant for biotechnology applications. (Summary by Daniel Czerny) Sci. Reports 10.1038/srep40844