ZmCCT-associated QTL Regulates Flowering and Stress Responses under Long-Day Conditions

Photoperiodism is the ability of plants to measure day length, enabling plants to coordinate internal activities with external changes to ensure normal growth. The ZmCCT gene was previously identified as a homolog of the rice photoperiod response regulator Ghd7, and associated with the major QTL responsible for Gibberella stalk rot resistance in maize. However, its regulation has not been studied.

Henan Agricultural University researchers mapped the ZmCCT-associated QTL (ZmCCT-AQ). The trascriptomes of a photoperiod-insensitive inbred line Huangzao4 (HZ4) and its near-isogenic line (HZ4-NIL), containing ZmCCT-AQ, were sequenced and compared. Analysis found that a set of genes exhibited higher basal expression levels in HZ4-NIL than in HZ4.

These upregulated genes were associated with responses to circadian rhythm changes and biotic and abiotic stresses. The HZ4-NIL exhibited enhanced drought and heat tolerance, and stronger disease resistance compared to HZ4. Further analysis suggests that ZmCCT and ZmCCA1, one of the circadian clock core genes, are important nodes linking photoperiod to stress tolerance responses under long day conditions.

For more on this study, read the article in BMC Plant Biotechnology.