Arabidopsis thaliana semi-dwarf accessions carry inactive alleles at the gibberellin biosynthesis GA5 locus. Barboza-Barquero et al. check for pleiotropic effects in the root system of semi-dwarfs in comparison with tall, near-related accessions and find some GA5 mutations with decreased root length in comparison to the related wild types. However, the deepest root system was found in a semi-dwarf accession, and this was independent from the ga5 loss-of-function allele, as shown by co-segregation analysis. They conclude that the observed diversity in the root system growth and architecture occurs independently from semi-dwarf phenotypes, and is probably linked to a genetic background effect.
