Transcriptomic analysis revealed that short-day treatment of seedlings promotes flowering in maize (Zea mays L.).

Background: In this study, blockage of transition from vegetative to reproductive growth was observed in short-day maize (Zea mays L.) varieties under long-day conditions.

Methods: Two short-day varieties, namely, CML116 and CML493, were cultivated under long-day conditions at various time points of short-day treatments of seedlings. Notably, short-day treatment was started at the three-leaf stage and ended at the five- (5 L), seven- (7 L) and nine-leaf (9 L) stages. Moreover, transcriptomic analysis (RNA-seq) was carried out to examine the gene expression profiles.

Results: The results of gene functional analysis showed that DEGs related to light stimulation and circadian rhythm had different expression patterns among various groups. Additionally, ZmCO, ZmSOC1, ZmFT and ZmHY5 acted as the key regulators of the transition process from vegetative to reproductive growth. Furthermore, the expression of most CO transcripts reached a peak at 5 L in both CML493 and CML116 but decreased in the subsequent short-day treatment.

Conclusions: It is possible that accumulation of CO and FT at the seedling stage facilitated transition from vegetative to reproductive growth. In addition, long-day conditions were not conducive to the accumulation of CO and FT as well as their downstream target, SOC1. Moreover, accumulation of the HY5 protein promoted photomorphogenesis, which played a positive role in promoting the normal development of maize plants.