Dev113878 1..10

Tissuemorphogenesis inplants requirescommunicationbetweencells, a process involving the trafficking ofmolecules through plasmodesmata (PD). PD conductivity is regulated by endogenous and exogenous signals. However, the underlying signaling mechanisms remain enigmatic. In Arabidopsis, signal transduction mediated by the receptor-like kinase STRUBBELIG (SUB) contributes to inter-cell layer signaling during tissue morphogenesis. Previous analysis has revealed that SUB acts non-cell-autonomously suggesting that SUB controls tissue morphogenesis by participating in the formation or propagation of a downstreammobile signal. A genetic screen identified QUIRKY (QKY), encodingapredictedmembrane-anchoredC2-domain protein, as a component of SUB signaling. Here, we provide further insight into the role ofQKY in this process.We show that likeSUB,QKY exhibits non-cell-autonomywhenexpressed in a tissue-specificmanner and that non-autonomyofQKYextendsacrossseveral cells. Inaddition, we report on localizationstudies indicating thatQKYandSUB localize to PDbut independently of eachother. FRET-FLIM analysis suggests that SUB and QKY are in close contact at PD in vivo. We propose a model where SUB and QKY interact at PD to promote tissue morphogenesis, thereby linking RLK-dependent signal transduction and intercellular communication mediated by PD.