Effects of applied ethrel, jasmonic acid, and salicylic acid on the formation of traumatic resin ducts in the bark of Thujopsis dolabrata cuttings and xylem of Metasequoia glyptostroboides seedlings

Abstract

Key message: Combined application of ethylene and jasmonate is a strong signal that leads to an increased magnitude of defense induction in two Cupressaceae species. Abstract: Ethrel (Et), methyl jasmonate (MJ), sodium salicylate (NS), and combinations of these compounds were applied to unwounded or wounded stems of Thujopsis dolabrata cuttings and Metasequoia glyptostroboides seedlings to clarify the mechanism of anatomical defense responses in Cupressaceae species. The application of MJ clearly induced the formation of abundant traumatic resin ducts (TRDs) in T. dolabrata, whereas the application of Et in M. glyptostroboides induced TRD formation rather than MJ. In both T. dolabrata and M. glyptostroboides, Et + MJ application induced massive tangential TRDs in the phloem or xylem. NS application did not significantly promote TRD formation in either species. Additionally, the application of NS with Et decreased resin duct formation in M. glyptostroboides compared with single Et application. These results indicate that Et and MJ application is a strong signal that leads to an increased magnitude of defense induction but no difference in species responsivity. Wounding increased TRD formation in the bark of T. dolabrata cuttings over that in unwounded cuttings under all treatments, whereas wounding in M. glyptostroboides showed little effect. These differences in anatomical responses may imply the strong constitutive defenses function by bark of T. dolabrata. © 2022, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.