Stone cell biogenesis in conifers

Stone cells are tough, highly lignified cells found throughout the plant kindom. Stone cells function as a dose-dependent constitutive physical defense of conifers against stem feeding insects. In Sitka spruce, increased quantities of stone cells in apical shoot tips is associated with resistance to spruce weevil. However, little is known about the molecular mechanisms and genes involved in their formation. We evaluated differences in gene expression of developing stone cells isolated from resistant (R) and susceptible (S) Sitka spruce genotypes with high and low quantities of cortical stone cells. Gene expression differences were compared using RNA-seq data of laser microdissected developing stone cells and undifferentiated cortical parenchyma cell types. Transcriptomic differences between R and S spruce revealed novel stone cell associated gene targets between genotypes. The new information regarding stone cell associated genes from R spruce will assist the rapid selection and breeding of weevil resistant Sitka spruce with traits specific to an overall enhanced conifer defense syndrome.