Ultrasonic seed treatment improved seed germination, growth, and yield of rice by modulating associated physio-biochemical mechanisms.

Ultrasonic seed (US) treatment could alter seed germination mechanism, however, US induced alterations in morph-physiological attributes and yield of fragrant rice were rarely reported. In the present study, the seeds of three fragrant rice cultivars viz., Xiangyaxiangzhan, Meixiangzhan 2, Ruanhuayou 6100 and one non-fragrant rice viz., Wufengyou 615 were exposed to ultrasonic waves at 20-40 kHz for 1.5 min (T) whereas the seeds without exposure were taken as control (CK). Results showed that US treatment caused minor cracks on seed surface while improved seed germination rate (1.79 %-11.09 %) and 3-indoleacetic acid (IAA) (3.36 %-46.91 %). Furthermore, peroxidase (POD) activity and methionine sulfoxide reductase activity was increased by 29.15 %-74.13 % and 11.26 %-20.87 %, respectively; however, methionine sulfoxide reductase related protein repairing gene MSRA4 was down-regulated by 17.93 % -41.04 % under T, compared to CK. Besides, US treatment also improved soluble protein in flag leaf (0.92 %-40.79 %), photosynthesis (3.37 %-16.46 %), biomass (5.17 %-31.87 %), as well as 2-acetyl-1-pyrroline content (4.77 %-15.48 %) in rice grains. In addition, multivariate analysis showed that the dry weight at the maturity stage were significantly related to the POD, glutathione reductase (GR) activity, IAA, and abscisic acid (ABA) content while germination rate was positively related to the GR activity, ABA content, and yield, but which were negatively related to the IAA and gibberellic acid content.

Transcriptome Analysis Revealed the Mechanisms Involved in Ultrasonic Seed Treatment-Induced Aluminum Tolerance in Peanut.

Ultrasonic (US) treatment is an efficient method to induce crop tolerance against heavy metal toxicity; however, US-induced aluminum (Al) tolerance in peanuts was rarely studied. This study was comprised of two treatments, namely, CK, without ultrasonic treatment, and US, an ultrasonic seed treatment, for 15 min. Both treated and non-treated treatments were applied with Al in the form of AlCl3.18H2O at 5 mmol L-1 in Hoagland solution at one leaf stage. Results depicted that plant height, main root length, and number of lateral roots increased significantly under US treatment. Transcriptome analysis revealed that plant hormone signal transduction and transcription factors (TFs) were significantly enriched in the differentially expressed genes (DEGs) in US treatment, and the plant hormones were measured, including salicylic acid (SA) and abscisic acid (ABA) contents, were substantially increased, while indole acetic acid (IAA) and jasmonic acid (JA) contents were decreased significantly in US treatment. The TFs were verified using quantitative real-time (qRT)-PCR, and it was found that multiple TFs genes were significantly upregulated in US treatment, and ALMT9 and FRDL1 genes were also significantly upregulated in US treatment. Overall, the US treatment induced the regulation of hormone content and regulated gene expression by regulating TFs to improve Al tolerance in peanuts. This study provided a theoretical rationale for US treatment to improve Al tolerance in peanuts.