Localization of tomato (Solanum lycopersicum) R3 MYB protein encoded by SlTRY in Arabidopsis roots

CAPRICE (CPC), an R3-type MYB transcription factor, is known to promote root hair differentiation in the root epidermis of Arabidopsis. CPC moves from non-hair cells to adjacent hair-forming cells. In contrast, we have previously shown that there is no movement of the CPC homologs, ENHANCER OF TRY AND CPC 1, 2, and 3 (ETC1, 2, and 3), and TRYPTICHON (TRY) between root epidermal cells. We also identified a tomato homolog of CPC, named Solanum lycopersicumTRYPTICHON (SlTRY).SlTRY-introduced transgenic Arabidopsis produced many root hairs, like CPC-introduced transgenic Arabidopsis. To clarify the cell-to-cell movement ability of the SlTRY protein, in this study, we observed the distribution of GFP fluorescence in CPCp:SlTRY:GFP transgenic Arabidopsis. Unexpectedly, SlTRY moved from non-hair cells to adjacent root hair cells, like CPC, in Arabidopsis root epidermis. SlTRY does not have the cell-to-cell movement sequence (S1) defined in CPC, and the mechanism of movement is still unknown. Further investigation is necessary to elucidate the mechanism of cell-to-cell movement of SlTRY. Our results will help in the further unraveling of the functions of these MYB transcription factors in determining cell fate.