Hydrogen Peroxide-Induced Oxidative Stress in Sugarcane and Response Expression Pattern of Stress-Responsive Genes Through Quantitative RT-PCR

Economic production of sugarcane is highly affected by oxidative stress due to biotic and abiotic stress factors. The main objective of this study was to determine which concentration of hydrogen peroxide can induce the oxidative stress conditions in sugarcane and determine whether several key gene expression responses reported in other species are triggered in sugarcane. Sixty-day-old sugarcane plants were sprayed with 30% H2O2 (300, 500 and 1000ppm) for three consecutive days. Controls were maintained by spraying with water. Quantitative RT-PCR was performed to quantify the gene expression levels. The PCR products were cloned and sequenced to confirm the identity of the gene amplified. The representative sequences of the stress-responsive genes were deposited in GenBank (Acc. No KX828698 for HSP gene, KX828699 for APX gene, KX828700 for NAC transcription factor and KX828701 for ERF transcription factor). The expression pattern of stress-responsive key genes (HSP, NAC, ERF, GST, MYBAS and CAT) showed higher expression levels within 48h of H2O2 treatment at 500 and 1000ppm concentration. However, MYBAS transcription factor and catalase genes showed higher expression levels at a higher concentration of H2O2 (1000ppm) of H2O2 at 48h of treatment. Ascorbate peroxidase gene was up-regulated at 1000ppm of H2O2 at 72h of treatment. NAC transcription factor, heat shock proteins, ethylene-responsive factor and glutathione S-transferase showed a significant increase in expression at 500ppm concentration of H2O2 at 48h. Based on the expression pattern levels, 500ppm of hydrogen peroxide at 48h can induce the oxidative stress in sugarcane. The expression levels indicated that HSP, NAC, ERF, GST and MYBAS genes might play a role in signal transduction pathways, and APX and CAT are involved in scavenging reactive oxygen species.