Light emitting diodes (LEDs) of different wavelengths significantly influenced kale growth, morphology, and nutrient content. The importance of indoor agriculture is being recognized, but few studies have investigated the influence of LEDs, particularly green wavelengths, on crops at the transcriptome level. The objective of this study was to use RNA sequencing technology to elucidate the genetic response of kale to blue (BV), green (G), and red (RF) LEDs compared to the combination of all the LEDs (RFBVG), control. Results revealed total amount of differentially expressed genes (DEGs) was 1373 for kale grown under BV LEDs, 924 under G LED, and 133 under the RF LED treatments. DEGs enriched in kale grown under RF LEDs played roles in regulating hormone metabolic processes and oxidoreductase activity. In the BV treatment, several enzymes in the phenolic biosynthetic pathway were upregulated compared to the control which may explain previous results reporting higher levels of phenolic content in kale grown under BV LEDs. In the G LED treatment, the expression of genes related to photosynthesis, heme binding, and oxidoreductase activity were upregulated compared to those in the control group. These results may support previous findings of higher iron content in kale grown under G LEDs. Further, the G LED treatment upregulated the expression of cytochrome P450 enzymes, which play key roles in plant growth and stress responses. Understanding the molecular mechanisms underlying the effects of different LED wavelengths by RNAseq provides information to improve indoor cultivation practices that optimize crop growth and nutrient value.
