Investigation of microRNA-mediated redox regulation in leaf growth regions during chiling stress tolerance of maize (Zea mays L.)

Corn (Zea mays L.) is one of the temperate climate crops, very sensitive to chilling stress and needs relatively high temperature for optimum growth and high yield. Chilling stress disrupts growth processes coupled with disruption of redox homeostasis of the cell, leading to oxidative stress. It is also known that the low amount of reactive oxygen species (ROS) released during this period promote growth. From that view, the aim of this study was to investigate the possible microRNA (miRNA) mediated regulation of ROS playing signalling role in leaf growth response against the chilling stress of maize seedlings. In this respect, ROS production was triggered by applying low night temperature stress to maize hybrid seedlings named ADA313. The antioxidant genes that play a major role in the redox regulation and the microRNAs targeting them were determined by in silico analysis and the relationship between them was validated at the transcriptional and enzymatic level. As a result, the elongation rate of the fourth leaf was reduced by 19% by chilling stress compared to control. miR528, which was predicted to target SOD 1a gene was found meristem and stress specific. The expression of miR397, which was predicted to target Laccase, was detected at maturity. Enzymatic activities of catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR), peroxidase (POX) and ascorbate peroxidase (APX) were found to differ between the growth regions. In this study, the miRNA-mediated regulation of the oxidative signaling pathway was shown for the first time in the leaf growth zones of maize response to chilling stress