Keep a distance to be different: axillary buds initiating at a distance from the shoot apical meristem are crucial for the perennial lifestyle of Arabis alpina.

In many seed plants, perennialism is achieved through axillary buds and side shoots that remain vegetative. This work aimed to analyse the pattern of axillary bud (AB) formation in the perennial model plant Arabis alpina and to study the role of the LATERAL SUPPRESSOR (AaLAS) gene. This study combines stereomicroscopic analysis with RNA sequencing to monitor the correlation between patterns of AB formation and gene expression. The role of AaLAS was studied using an RNA interference (RNAi) approach. During vegetative development, ABs initiate at a distance from the shoot apical meristem (SAM), whereas after floral induction, they initiate adjacent to the SAM. Dormant buds are established before the onset of vernalization. Transcript profiles of ABs initiated at a distance differed from those in the SAM, whereas those of buds initiated in close proximity were similar. Knockdown of AaLAS leads to the loss of dormant buds and vegetative side shoots, strongly compromising the perennial life cycle. AB formation is regulated differently during vegetative and reproductive development. New meristems that possess different gene expression profiles from those in the SAM are established at a distance from the SAM. AaLAS is essential for the perennial life cycle by modulating the establishment of dormant buds and vegetative side shoots.