Gene groups of the vernalization requirement (VRN) and the photoperiod sensitivity (PPD) play key roles in the molecular genetic regulation of environmental adaptation of cereals. During vernalization, VRN1 gene is gradually activated by the cold and the increasing volume of VRN1 transcription factor inhibits the function of VRN2 and, stimulates the VRN3 gene, which enhances the induction of flowering. PPD1 genes are important in fine-tuning of these processes.For the plant developmental dynamics, temperature has a much more complex effect than photoperiod. In the present work, we examined how the expression patterns of the four major developmental genes (VRN1, VRN2, VRN3 and PPD1) are influenced by temperature under different photoperiods (long day [LD]: 16h and short day [SD]: 12h illumination) in two wheat cultivars with different developmental dynamics: ‘Mv Toborzó’ with early and ‘Charger’ with late heading. The plants were grown under controlled environmental conditions.In the case of VRN1, under LD, the difference between the two cultivars increased with the lower temperature and became significant at 11 °C, while under SD, the PPD-insensitive type (‘Mv Toborzó’) had higher VRN1 level not only at 11 °C but also at 25 °C. Under LD, the transient expression level of VRN2 was the highest in the case of the PPD-sensitive type (‘Charger’), irrespective to the temperature level. Under SD, this tendency could be observed at 11 °C and 18 °C treatments. The VRN3 expression of the PPD-insensitive type was significantly the highest at 18 °C and 11 °C under LD, while only at 11 °C under SD. PPD1 activity was lowest at 11 °C and showed a gradual but continuous decrease in expression in both cultivars. Under LD, the PPD1 activity in the PPDinsensitive type (‘Mv Toborzó’) was 2-4 times higher compared to the PPD-sensitive type (‘Charger’), irrespective to the ambient temperature. Under SD, this difference between the insensitive and sensitive types mostly diminished. The intensive stem elongation phase of ‘Mv Toborzó’ accelerated at 25 °C, while the developmental dynamics of ‘Charger’ was significantly delayed even in inductive environments.

Acknowledgement. This research was partly funded by national research grant from the Hungarian Scientific Research Fund (GINOP-2.3.2-15-2016-00029) and partly by EU via the ADAPTAWHEAT EU-FP7 research grant.