Microwave pre-stimulation methodology for plant growth promotion.

Although positive effects of microwave irradiation on plants have been reported, their underlying mechanisms remain unknown. In this study, we investigated the effects of low microwave irradiation on Arabidopsis thaliana. Interestingly, we found low output (23 W) with oscillating condition (not continuous irradiation) promoted plant growth. The microwave irradiation neither raised the plants' temperature nor induced heat responsive gene expression. Furthermore, overall transcriptome profile in microwave irradiation treated plants were significantly different from heat treated plants, suggesting that growth promotion might be attributed to non-thermal effects of microwave. Transcriptome and metabolome analysis indicated that microwave irradiation altered circadian clock as well as hormonal response especially in auxin and gibberellin, which promoted plant growth by inducing amino acid biosynthesis and stress tolerance, and reducing cell wall thickness. This finding potentially contributes to develop new approach to increase food production through accelerating crop yield in environmentally friendly way.