Patterns of mitochondrial gene expression in rapeseed leaves (Brassica napus L.) at early growth stage in response to drought stress

Drought stress adversely affects a plant’s growth and productivity. Wide ranges of molecular disorders could be caused by the production of reactive oxygen radicals. Plant cells have developed potential systems to prevent such damage by scavenging and reducing the reactive oxygen species (ROS). In this study, both the genotypes of oilseed rape-tolerant and sensitive to drought-were exposed to polyethylene glycol (PEG)-induced osmotic stress at various intervals to screen the expression of mitochondrial genes that are involved in oxidizing excessive NAD(P)H without producing adenosine triphosphate (ATP). Results showed that the maximum number of alternative oxidase 1a (AOX1a) gene expression occurred in Hyola308 after 12 hours of water stress. Meanwhile, no change was observed in other sampling times. However, in SLM046, the gene expression had gradually been increased during the stress and the maximum expression was observed after 24 hours of stress. The expression of uncoupler (UCP) gene, in SLM046, was increased during the water stress and its maximum expression was observed at eight and 24 hours after the stress. However, the maximum UCP expression in Hyola308 occurred around the 12-hour mark after the stress as an AOX gene expression. Moreover, the expression of external NADPH dehydrogenase (exNDH) was increased at the early hours of the stress in Hyola308 while the same was done during the final hours of stress in SLM046.Our results showed that high activity of the mitochondrial genes, alone or together, could also be an important factor in drought tolerance in oilseed rape crop by detoxifying the harmful effects of the ROS.