Expression patterns of orthologous genes can be similar between distantly related species, suggesting that developmental programs can be conserved between organisms. Here, we show that the promoter of AHP6, a gene which is involved in Arabidopsis lateral root development, also drives the expression of the reporter GUS gene in lateral roots of Medicago truncatula suggesting that similar regulatory elements are involved in lateral root organogenesis in these species. Interestingly, the AHP6 promoter was able to drive GUS expression in root nodules and nodule primordia, structures that are absent in Arabidopsis. We found two AHP6 orthologous genes in the M. truncatula genome and we speculate that these putative cytokinin inhibitors may play a role during lateral root and nodule development in this species.
Keywords: cytokinin; gene expression; lateral roots; orthologous genes; root nodules.