Transcriptome analysis revealed mechanisms involved in improved germination and growth of sugarcane by ultrasonic treatment

Ultrasonic treatment within a suitable range often has positive effects on seed germination and plant growth. In the present study, three sugarcane varieties, ROC22 (V1), LC05–136 (V2), and YT93–159 (V3), were treated with ultrasound waves with a mixed frequency of 20–40 kHz for 1, 2, and 5 min. Moreover, the changes in the transcriptome of the sugarcane variety ROC22 with and without ultrasonic treatment at 0, 6, and 12 days of germination were studied. The results showed that suitable ultrasonic treatment substantially increased the length, diameter, and germination rate of sugarcane buds and significantly improved the antioxidant enzyme activities of sugarcane to prevent oxidative burst of reactive oxygen species (ROS) from damaging cell membranes. A total of 2756 differentially expressed unigenes (DEGs) (1395 upregulated and 1361 downregulated) were identified in the day 0 comparison; a total of 831 DEGs (408 upregulated and 423 downregulated) were identified in the day 6 comparison, and 5987 DEGs (1862 upregulated and 4125 downregulated) were identified in the day 12 comparison. Furthermore, ultrasonic treatment significantly affected the hormone synthesis pathways, reduced the contents of auxin (IAA), abscisic acid (ABA), and jasmonic acid (JA), and increased the ratio of IAA/ABA to promote germination. The gene expression of gibberellin (GA) synthesis was upregulated, whereas the gene expression of ABA synthesis was downregulated, resulting in improved germination of sugarcane buds. Overall, the optimal exposure time for ultrasonic treatment differed among the varieties; however, an appropriate ultrasonic treatment could regulate the antioxidant system and hormone synthesis pathways, thereby promoting the germination of sugarcane. This study provides a theoretical basis and technical support for ultrasonic treatment employed to promote sugarcane germination and growth. [Display omitted] •First application of transcriptome analysis reveals the mechanism by which ultrasound promotes sugarcane germination.•Appropriate ultrasonic treatment inhibit ROS burst of sugarcane.•Appropriate ultrasonic treatment regulated gene expression of hormones such as IAA, ABA, and JA.