A negative feedback loop regulating inflorescence development in plants

The inflorescence is a crucial stage in the reproductive cycle of plants. During this phase, by perceiving both external (seasonal) and internal (endogenous) inductive signals, plants develop different floral buds. The architecture of this inflorescence will determine when the plant flowers and how many seeds it produces, two critical aspects for its reproductive success.

There are determinate inflorescences, where the inflorescence ends in a flower and no longer grows, and indeterminate inflorescences, where the inflorescence does not end in a flower and the plant continues producing flowers until it ages. This differentiation between determinate and indeterminate inflorescences occurs due to the different behaviour of the apical meristem, the region of the plant with stem cells capable of producing new organs.

In Arabidopsis, the inflorescence is indeterminate and is divided into two parts: in the first phase, the apical meristem continues to produce lateral meristems that give rise to indeterminate shoots in the form of leaves and stems, and, in the second phase, the lateral meristems produce determinate flowers when they perceive signals that induce flowering. This opposing response of the apical and lateral meristems to the same stimulus has been a great enigma in the field of plant science.
Researchers from the ‘Synthetic biology of plant signaling circuits’ group at CBGP have participated in an international study published in Science that reveals the molecular mechanism that allows two types of meristems in close proximity (apical and lateral) to offer opposing responses to the same systemic signal.

A negative feedback loop

Researchers have combined experimental data with computer modelling to elucidate a negative feedback loop at the center of the apical meristem, responsible for inflorescence development, which acts as a buffering response to the floral inductive signal.

This negative feedback loop, involving the master transcription factor LEAFY (LFY) and the transcriptional corepressor TERMINAL FLOWER1 (TFL1), allows for the dynamic and precise control of LFY accumulation, thereby blocking inflorescence meristem termination.

Inflorescence determination is a key agronomic trait, and the new findings opens the door to crops with shorter growth cycles, higher planting densities, and more efficient harvesting.