Warming and elevated CO₂ alter the transcriptomic response of maize (Zea mays L.) at the silking stage

Exploring the transcriptome of crops in response to warming and elevated CO₂ (eCO₂) is important to gaining insights of botanical adaption and feedback to climate change. This study deployed Illumina sequencing technology to characterize transcriptomic profile of maize plants at the silking stage, which were grown under warming (2 °C higher than ambient temperature) and eCO₂ (550 ppm) conditions. The treatment of ambient temperature and ambient CO₂ concentration was considered as control (CK). Warming, eCO₂ and warming plus eCO₂ resulted in 2732, 1966 and 271 genes expressing differently (DEGs) compared to the CK, respectively. Among the DEGs, 48, 47 and 36 gene ontology (GO) terms were enriched in response to warming, eCO₂ and warming plus eCO₂ compared to the CK, respectively. The majority of genes were assigned to the biological process category and the cellular component category. Elevated CO₂ significantly inhibited gene expressions in terms of photosynthesis and carbohydrate biosynthesis pathways. Warming not only negatively affected expressions of these genes, but also secondary pathways of nitrogen (N) metabolism, including key enzymes of GST30, GST7, GST26, GST15, GLUL and glnA. These results indicated the negative biochemical regulation and physiological functions in maize in response to warming and eCO₂, highlighting the necessity to improve the genetic adaptability of plant to future climate change.