A tribute to Georges Bernier (1934–2023)

Professor Georges Bernier passed away on 31st August 2023, at the age of 89. He was Professor Emeritus at the University of Liège, Belgium, and a member of the Royal Academy of Belgium (Class of Sciences) and of the Academy of Agriculture, France.

Georges Bernier was an internationally renowned and pioneering researcher who dedicated his whole career to the understanding of flowering and to the quest of identifying the physiological signals controlling the reprogramming of the shoot apical meristem (SAM). His interest in the flowering process started in the early 1960s during his PhD, for which he selected Sinapis alba, white mustard, as an experimental model plant. This choice later proved to be fortunate, as this species belongs to the Brassicaceae family and is a close relative to Arabidopsis. He set up an experimental system for inducing flowering by a single photoperiodic cycle (one long day) and, with his group, he dissected hour by hour the changes that occur at the whole-plant level during the transition to flowering. He introduced the concept of ‘multifactorial control of flowering’ to account for the changes in hormones and other metabolites (assimilates) originating from leaves and roots that could trigger the early changes occurring in the SAM during evocation, such as the activation of cell division and doming (Bernier et al., 1981b). He enjoyed recounting the impassioned and (sometimes) heated debates that took place during congresses at that time around the quest for ‘florigen’.

Beside Sinapis, he supervised similar research on the long-day grass Lolium temulentum and the short-day plant Xanthium strumarium, and later embraced the use of Arabidopsis in the 1990s. He also ran a center of applied research in which horticultural and ornamental plants such as tomato, strawberry, and azalea were studied. Between 1981 and 1985 with his colleagues and friends Jean-Marie Kinet (then at University of Liège, later UCLouvain) and Roy Sachs (University of California, Davis), he published a book series of three volumes on ‘The Physiology of Flowering’ from floral induction to flower development, which remains a major reference for its deep and exhaustive coverage (Bernier et al., 1981a, 1981b; Kinet et al., 1985).

Georges Bernier was the Editor of the Flowering Newsletter (FNL) from 1989 to 2005, taking over this position after A. Halevy, who created the FNL in 1986. In the 34 FNL issues that he edited, he liked to illustrate some contributions or opinions with cartoons drawn by Yves Lemoine. The one shown above, dating from May 1991, illustrates the challenge that he took up with enthusiasm after the emergence of Arabidopsis as the model organism of choice for research in plant biology: to integrate physiological and molecular/genetic approaches to acquire a comprehensive understanding of the flowering process (Bernier and Périlleux, 2005).

Georges Bernier continued to edit the FNL after his official retirement from the University of Liège in 1999, and he passed the torch to Nick Battey (University of Reading) in 2005. By a quirk of fate, this handover shortly preceded the discovery of the FLOWERING LOCUS T (FT) protein as the mobile florigen that had been so eagerly searched for, and the cartoon (below) from the last FNL issue that Georges Bernier edited shows his endless questioning about its multiple components. The integration of the FNL into the Journal of Experimental Botany occurred in 2006, on which occasion a symposium on the ‘Major Themes in Flowering Research’ was organized in Georges Bernier’s honor in Canterbury, UK, in the presence of eminent members of the flowering community (see the Special Issue of the Journal of Experimental Botany, volume 57, issue 13).

A hard worker and insatiable researcher, Georges Bernier kept abreast of discoveries about florigen and remained thirsty for knowledge during his whole life. In the 2011 issue of the FNL, he presented his favorite picture: a longitudinal section of the SAM showing, by in situ hybridization, the activation of SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) by the application of exogenous cytokinin, the hormone family that he had shown to be part of the physiological signals of flowering in Sinapis (Bernier, 2011). In 2013, he wrote the book ‘Darwin, un pionnier de la physiologie végétale’, for which he captivatedly read the books of Charles Darwin, relived his fascination for plants, and highlighted the input of his son, Francis Darwin (Bernier, 2013).

Beside his research career, Georges Bernier was an outstanding teacher of plant physiology who transmitted his passion to dozens of Master’s and PhD students. As one of his former students and on behalf of all those with whom he communicated his passion for flowering, I wish to express to him our warmest gratitude for his mentoring, and offer our most sincere condolences and support to his wife, Martine.