Abstract
Plant 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 summary Somatic mutations in fruit trees occur in specific cell layers.
Competing Interest Statement
The authors have declared no competing interest.