Leaf transcriptome analysis of Lancaster versus other heterotic groups' maize inbred lines revealed different regulation of cold-responsive genes

One of the strategies for overcoming global climate change threatening to decrease maize yield is early sowing. To contribute to the development of cold-tolerant hybrids this research focused on the genetic background's comparative analysis in maize inbreds with good combining ability. Leaf whole-transcriptome sequencing of 46 maize genotypes revealed 77 differentially expressed genes (DEGs) between Lancaster and other heterotic groups (i.e. BSSS, Iowa dent, Ohio), referred to as non-Lancaster group, under optimal growing conditions. Cold test of the subset of four Lancaster and four non-Lancaster lines showed that the former were cold sensitive and the latter cold tolerant. Cold-induced expression analysis of seven DEGs in eight lines revealed different expression regulation dependent on the duration of cold exposure and genetic background for six out of seven analysed genes-chloroplast ATP-sulphurylase, photosystem II cytochrome b559 alpha subunit, CIPK serine-threonine protein kinase 15, glutamyl-tRNA reductase, photosystem II reaction centre protein I and Calvin cycle CP12-chloroplastic-like encoding genes. The results imply that differently regulated basic processes between Lancaster and non-Lancaster maize group involve, at least, photosynthesis and sulphate assimilation, contributing to their different cold response and different adaptation to low temperatures.