The transcriptional changes underlying the flowering phenology shift of Arabidopsis halleri in response to climate warming

Climate warming is causing shifts in key life-history events, including flowering time. To assess the impacts of increasing temperature on flowering phenology, it is crucial to understand the transcriptional changes of genes underlying the phenological shifts. Here, we conducted a comprehensive investigation of genes contributing to the flowering phenology shifts in response to increasing temperature by monitoring the seasonal expression dynamics of 293 flowering-time genes along latitudinal gradients in the perennial herb, Arabidopsis halleri. Through transplant experiments at northern, southern and subtropical study sites in Japan, we demonstrated that the flowering period was shortened as latitude decreased, ultimately resulting in the loss of flowering opportunity in subtropical climates. The key transcriptional changes underlying the shortening of the flowering period and the loss of flowering opportunity were the diminished expression of floral pathway integrator genes and genes in the gibberellin synthesis and aging pathways, all of which are suppressed by increased expression of FLOWERING LOCUS C, a central repressor of flowering. These results suggest that the upper-temperature limit of reproduction is governed by a relatively small number of genes that suppress reproduction in the absence of winter cold.

Automated summary

Climate warming affects the shifting of key life-history events, such as flowering time. Understanding the transcriptional changes of genes is crucial in assessing the impact of increasing temperature on flowering phenology. This study investigated the seasonal expression dynamics of 293 flowering-time genes in Arabidopsis halleri along latitudinal gradients in Japan. The results showed that the flowering period was shortened with decreasing latitude, leading to a loss of flowering opportunity in subtropical climates. The diminished expression of floral pathway integrator genes, gibberellin synthesis genes, and aging pathway genes, which are suppressed by the increased expression of FLOWERING LOCUS C, a key repressor gene, were found to be the key transcriptional changes underlying the shortening of flowering period and loss of flowering opportunity. These findings suggest that a small number of genes play a significant role in regulating the upper-temperature limit of reproduction in the absence of winter cold.