The majority of somatic mutations in fruit trees are layer-specific

Abstract

AbstractPlant meristems consist of three distinct stem cells layers. The identities of these layers are maintained in developing organs. Somatic mutations in the meristem thus propagate only into the respective layers of the differentiated organs. We analysed the genomes of individual cell layers in an apricot tree and found an unexpectedly high mutation load, where >90% of the somatic mutations were layer-specific. The layers had similar mutation spectra but layer 1 (epidermis) had substantially more mutations than layer 2 (mesocarp). Most somatic mutations were shared between fruits and neighbouring leaves corroborating their meristematic origin. Single-cell transcriptomics revealed their layer-specific effects forming the basis for layer-specific phenotypes. Our work unveils the hidden abundance of layer-specific meristematic mutations and provides insights into their identification and understanding.One sentence summarySomatic mutations in fruit trees occur in specific cell layers.