The lack of soil nitrogen impacts the yield and quality of maize, which is a major problem of maize production in China. ZmCCT10 encodes the transcription factor, which is pleiotropic. ZmCCT10 is a very important co-factor regulating the growth, development and responding to abiotic stress of maize. The molecular mechanism of maize tolerance to low nitrogen is the basis for breeding maize varieties with low nitrogen tolerance and high nitrogen efficiency.

In this study, we compared the traits those relate to low-nitrogen tolerance, expression pattern of ZmCCT10 and transcriptome results of ZmCCT10 near-isogenic lines under low-nitrogen stress and complete nutrient conditions. To analysis the characteristics of ZmCCT10 in response to low-nitrogen stress and the molecular mechanisms involved in low-nitrogen tolerance were explored.

This study indicated that different alleles of ZmCCT10 showed significant differences in root length traits, biomass and nitrogen physiological traits under low nitrogen stress. The Y331-ΔTE haplotype without transposon insertion of ZmCCT10 had significantly longer total root length, main radicle length and lateral root length than Y331 after low nitrogen stress. What is more, root dry weight, shoot dry weight, nitrogen accumulation and nitrate reductase activity were also significantly higher than Y331. The expression levels of ZmCCT10 in roots and leaves were significantly higher than those in the control treatment. The expression level of ZmCCT10 in roots reached a peak at 3 hours after stress treatment. In leaves, the expression of ZmCCT10 continued to increase and peaked 6 hours after stress treatment. Root samples were collected under 0.04 mmol·L^-1 low nitrogen stress after 3h for transcriptome sequencing. The correlation coefficients between biological replicates are more than 0.9. GO enrichment analysis showed that the expression levels of amine synthesis process and cellular nitrogen compound catabolic process were significantly different in near-isogenic lines after low nitrogen stress. Combined with the amount and expression pattern of differential genes, ZmCCT10-regulated candidate genes involved in low-nitrogen tolerance were selected. qRT-PCR confirmed that the expression levels of ZmMPK5, ZmNS2 and other genes were significantly different after stress in near-isogenic lines.

ZmCCT10 is a candidate gene involved in low nitrogen tolerance in maize and it participates in the low-nitrogen tolerance response of maize as transcriptional regulation.