The genus Achillea (Asteraceae) shows a great diversity in leaf dissection patterns. Leaf shape is one of the most variable traits of plants, and the transcription factor NAM is known to regulate development of leaf serration in Arabidopsis.
Sha et al. investigate whether NAM also underpins leaf dissection in Achillea, and whether modification of its activity is responsible for changes to leaf form in this genus. The NAM gene was isolated from A. acuminata with serrate leaves and A. asiatica with 3-pinnatisect leaves, and in situ mRNA hybridization and quantitative PCR was conducted to determine the gene’s expression in their leaves. Both methods showed altered NAM expression dynamics in serrate versus pinnate leaves. This study provides important insights into the genetic factors leading to changes of leaf forms in processes of speciation.