Sodium carbonate(Na2CO3)presents a huge challenge to plants by the combined damaging effects of Nat,high pH,and CO32-.Little is known about the cellular responses to Na2CO3stress.In this study,the transcriptome of maize(Zea mays L.cv.B73)roots exposed to Na2CO3stress for 5 h was compared with those of NaCl and NaOH stresses.The expression of 8,319 genes,representing over a quarter of the total number of genes in the maize genome,was altered by Na2CO3stress,and the downregulated genes(5,232)outnumbered the upregulated genes(3,087).The effects of Na2CO3differed from those of NaCl and NaOH,primarily by downregulating different categories of genes.Pathways commonly altered by Na2CO3,NaCl,and NaOH were enriched in phenylpropanoid biosynthesis,oxidation of unsaturated fatty acids,ATP-binding cassette(ABC)transporters,as well as the metabolism of secondary metabolites.Genes for brassinosteroid biosynthesis were specifcally upregulated by Na2CO3,while genes involved in ascorbate and aldarate metabolism,protein processing in the endoplasmic reticulum and by N-glycosylation,fatty acid biosynthesis,and the circadian rhythm were downregulated.This work provides the frst holistic picture of early transcriptomic adaptation to Na2CO3stress,and highlights potential molecular pathways that could be manipulated to improve tolerance in maize.
