2,3-Butanediol induces brown blotch resistance in creeping bentgrass by strengthening cell wall structure and promoting lignin synthesis of precursor phenolic acid

Brown blotch caused by Rhizoctonia solani is among the most common Agrostis lawn diseases. Evidence shows that 2,3-butanediol (2,3-BD) induces and improves plant disease resistance. Herein, we treated Agrostis stolonifera L. Penn-A4 with 250 µmol/L 2,3-BD to induce resistance to brown blotch ( Rhizoctonia solani ). Changes in leaf ultrastructure were observed with a TECNAI-G 2 (TF20) electron microscope. The cell wall composition and phenolic acids used as precursors in lignin synthesis were determined by spectrophotometry and high-performance liquid chromatography. The disease index of creeping bentgrass decreased significantly following 2,3-BD induction. The disease index of the uninduced treatment increased to 70.45% on the 15th day after inoculation, 3.26 times higher than the 2,3-BD-induced treatment. The degree of damage to cells was significantly reduced after induction, chloroplasts were completely spindle shaped and appeared close to the cell wall, the cell wall was thicker with visible folds, and the cell wall cross section was more visible. The levels of lignin, cellulose, hemicellulose, pectin, and hydroxyproline-rich glycoprotein (HRGP) in leaves were significantly higher in induced plants than in non-induced plants. Lignin, hemicellulose, pectin, and cellulose of the induced plants peaked on the 13th, 9th, 11th, and 7th days, respectively, and were 5.7, 16.5, 0.9, and 17.6% higher than those of non-induced plants, whereas HRGP increased by 22.8 and 42.5% on days 7–9 compared to non-induced plants. The induced plants had significantly higher levels of p-coumaric acid, caffeic acid, ferulic acid, and sinapic acid. p-Coumaric acid peaked on the 7th and 15th days, when it was 1.38 and 1.12 times higher than in non-induced plants, respectively, while caffeic acid, ferulic acid, and sinapic acid peaked on the 9th, 11th, and 13th days, when it was 1.39, 1.11, and 1.16 times higher than in non-induced plants. The 2,3-BD treatment effectively strengthened cell wall structure and increased plant resistance by increasing the content of constituent substances in the cell wall and strengthening the cell wall. Also, the content of precursor substances for lignin synthesis increased. The findings demonstrate that 2,3-BD can effectively improve plant disease resistance.