Sound wave stimulates plant gene response and improve salt stress tolerance of rice seedlings

다국어 초록 (Multilingual Abstract)

We investigated whether sound could alter gene expression in plants. Using a sound-treated subtractive library, a set of sound-responsive genes in plants was demonstrated through mRNA expression analyses. Of them, the rbcS and ald genes, which are light responsive, up-regulated their expression with sound treatment in both light and in dark conditions. This suggested that sound could be used as a gene regulator instead of light. When we analyzed ald gene expression using various single wavelengths, a significant increase in mRNA levels was found at 125 or 250 Hz but decreased at 50 Hz, indicating that the gene responded to sound in a wavelength-specific manner. To determine whether the ald promoter respond to sound, we generated transgenic rice plants harboring the chimeric gene consisting of a 1,506-bp promoter fragment of the ald gene fused to Escherichia coli GUS reporter gene. Analyses of mRNA expressison level of three independent transgenic lines sound-treated with 50 or 250 Hz for 4 h showed that the Gus gene expression in all three transgenic lines was up regulated by 250 Hz, but down regulated by 50 Hz. These results correlated with sound responsive mRNA expression pattern observed for the ald gene in rice plants, indicating that the 1,506-bp ald promoter confers sound-responsiveness on a reporter gene in transgenic rice plants. We also investigated whether sound waves could improve salt tolerance in rice seedling. The rice seedlings were sound treated with 800 Hz for 1hr, and then treated with 0, 75, 150, and 225mM NaCl for 3 days to observe changes in physiological and morphological aspects. Sound treatment seedlings resulted in enhanced salt stress tolerance, mainly demonstrated by the sound treated seedlings exhibiting of increased root relative water contents (RWC), root length and weight, photochemical efficiency (ratio of variable to maximum fluorescence, Fv/Fm), and germination rate under salt stress condition. This demonstrates that a specific sound wave might be used, not only to alter gene expression in plant, but also to improve salt stress tolerance.