Identified a new key protein that controls flowering time in plants

The time of flowering initiation is essential for the reproductive success of plant species but also for the optimal production of fruits and seeds in crops. For that reason, plants have evolved to bear complex regulatory networks that control the time of flowering very precisely. A deep knowledge of these molecular mechanisms will allow the design of strategies to facilitate the adaptation of crops to fluctuating environmental conditions that threaten agricultural production in the current scenario of climate change.

This new study, published in Plant Physiology, reveals a novel chromatin remodelling factor involved in the control of flowering time. The protein ‘INHIBITOR OF GROWTH 2 (ING2)’ participates in the regulation of this developmental process through the direct transcriptional modulation of master genes that act as floral switches in plants.

The role of ING2 in the control of flowering initiation

ING2 is a chromatin reader protein that contains a domain called PHD (Plant HomeoDomain) finger, known to recognize particular posttranslational histone modifications associated with transcriptionally active genes. This specific binding allows ING proteins, highly conserved in eukaryotes, to orchestrate different cellular processes in plants and other organisms.

The work, led by CBGP researchers José Antonio Jarillo Quiroga and Manuel Ángel Piñeiro Galvín, reveals that ING2 proteins associate in vivo with multiple subunits of a histone acetyltransferase complex called NuA4 to control histone H4 acetylation levels throughout the genome of the model species Arabidopsis thaliana.

This covalent modification of histone H4 has a direct effect on the expression of underlying genes that, in turn, modulates different developmental processes including the initiation of flowering by directly controlling the transcription of master regulator genes of flowering. Interestingly, this works demonstrates that ING2 function in the control of flowering time is largely independent of the homologue protein ING1, also present in Arabidopsis. Moreover, the study unveils a genetic interaction between ING2 and genes encoding relevant proteins for the deposition of other chromatin modifications also modulating gene expression, suggesting that ING2 might represent a hub for potential crosstalk between different histone modifications/variants that end up finely tuning transcription.

This finding will help to understand in greater depth a key process in the reproductive cycle of plants and opens the possibility of developing new adaptation strategies in crops that are threatened by environmental fluctuations caused by climate change.