Dr. Bouzayen Mondher published 112 papers in both plant (Plant Cell, Plant Journal, Plant Physiology, New phytologist, Trends In Plant Science) and multi-disciplinary journals (PNAS, Nature Biotechnology, Nature and PLOS Genetics). His work is largely cited (over 7000 citations) giving him high recognition (h-index: 46). MB’s research addresses hormone signaling and epigenetic regulation fleshy fruit development. Tomato is the main model species and combined functional genomics and reverse genetics approaches are routinely implemented to uncover the physiological significance of regulatory genes. MB is coordinating the TomGEM H2020 project (2016 - 2020) and the COST Action FA1106 European research network on fleshy fruit (2012-2016). He led the French contribution to the “Tomato Genome Sequencing”.
The rapid world demographic growth along with the global climate change represent a serious threat in the ability of human society to provide sufficient amounts of high nutritional and sensory quality food. In higher plants, yield is a complex trait relying on the successful completion of flower pollination which can be impaired by environmental factors. Like other developmental shifts, the flower-to-fruit transition, so-called fruit setting, is associated with major transcriptomic reprogramming guided by the convergence between hormone signalling and epigenetic regulation. Histone marking and DNA methylation are the main epigenetic modes for genetic reprogramming, but their respective contribution to fruit setting remains unknown. In an attempt to clarify this issue, genome-wide transcriptomic profiling, ChIP-sequencing and DNA bisulfite sequencing were applied to tomato, a major economic crop and a model system for fleshy fruit. The study highlights the role of histone marking rather than DNA methylation in driving the transcriptomic reprogramming underlying fruit set and uncovers H3K9ac and H3K4me3 marks as primary players in this control mechanism. Consistently, the expression of fruit set-related genes such as those involved in hormone metabolism, cell division, and embryo development correlated with the appropriate histone mark repositioning, but not with changes in DNA methylation. The elucidation of the mechanisms underpinning fruit set, a major process impacting crop yield, represents a significant progress in our understanding of reproductive biology. In terms of applied outcome, the study identified epigenetic modifiers that are most active at this developmental shift, thus opening new leads towards improving fruit setting through providing new targets for breeding programs.