Identification and characterisation of candidate genes involved in chilling responses in maize (Zea mays L.)

Chilling stress can have severe impacts on the growth, development and productivity of maize worldwide. In the present study, cDNA amplified fragment length polymorphism (cDNA-AFLP) analysis was used to evaluate gene expression in maize during chilling treatments (6A degrees C) over four time periods (0, 2, 6 and 12 h). A total of 441 transcript-derived fragments (TDFs) induced by low-temperature treatment were detected. Based on the sequence analysis, the 58 TDFs of known functions were involved in metabolism, photosynthesis, signal transduction and defence responses etc., suggesting that maize undergoes a complex adaptive process in response to low temperatures. Three full-length cDNA, encoding MAPKKK (mitogen-activated protein kinase kinase kinase), CLC-D (chloride channel D) and RLK (receptor-like protein kinases) homologues, were isolated from maize through in silico cloning and named as ZmMAPKKK, ZmCLC-D and ZmRLK, respectively. Finally, the expression patterns of the three genes showed a significant increase of differential expression after chilling stress as analysed by semi-quantitative RT-PCR and real-time qRT-PCR. This study provides important clues to understanding low-temperature regulation mechanisms in maize and the three candidate genes involved in chilling responses need further research to determine their usefulness in breeding new resistance cultivars.