Promoting effects of <italic>Tulasnella</italic> sp. S7 metabolites on <italic>Dendrobium officinale </italic>seed germination

Abstract

<p indent="0mm">The seeds of the orchid<italic> Dendrobium officinale</italic> symbiotically germinated with <italic>Tulasnella</italic> sp. S7. The S7 extracts promoted germination. In this study, the ethyl acetate fraction of the S7 mycelium extract (MyE-E) and the petroleum ether and ethyl acetate fractions of the S7 fermentation broth extract (FBE-P and FBE-E) were confirmed to be active by activity tracking. Thereafter, the FBE-E chemical constituents were isolated by column chromatography and preparative high-performance liquid chromatography, and their activities were detected. Twelve compounds were isolated and elucidated as diisobutyl phthalate (<bold>1</bold>), dibutyl phthalate (<bold>2</bold>), indole-3-carboxaldehyde (<bold>3</bold>), vanillic acid (<bold>4</bold>), isovanillic acid (<bold>5</bold>), syringic acid (<bold>6</bold>), <italic>trans</italic>-ferulic acid (<bold>7</bold>), 3,5-dihydroxybenzoic acid (<bold>8</bold>), 3,4-dihydroxybenzoic acid (<bold>9</bold>), indole-3-carboxylic acid (<bold>10</bold>), 1,5,5-trimethyl-6-acetoxy-cyclohexen-3-one (<bold>11</bold>), and benzyl alcohol (<bold>12</bold>). Compounds <bold>4</bold> and <bold>12</bold> at 1 and <sc>100 μmol L⁻¹,</sc> respectively, accelerated seed germination and promoted the development of the protocorm on 1/2 MS medium; compounds <bold>3</bold> and <bold>10</bold> accelerated seed germination at <sc>100 μmol L⁻¹.</sc> This study clarified the active S7 metabolites that induce <italic>D</italic>.<italic> officinale</italic> seed germination for the first time.