BELLECOMBE Melvin

PhD student
In Plant Ecophysiology and physiologie

Team: MAGE

I graduated with a Master’s degree in Plant Biology, specializing in Phytoressources and Phytosciences from Lyon 1, I’m curently in thesis in the MAGE team at LEPSE. My thesis is about integrated analysis of wheat spike devlopment in response to climate change to identify resilience traits. 

Start of PhD: 1.11.2025

Subject:   Analysis of wheat spike development in response to climate change to identify resilience traits.nalyse intégrée du développement de l’épi de blé en réponse au changement climatique pour identifier des traits de résilience.

Abstract
The stagnation of wheat yields observed over the past several decades is partly atributed to climate change. To address this issue, it has become crucial to identify resilient wheat genotypes. One avenue for improvement lies in increasing the number of fertile flowers per spike (which directly affects grain number), a trait strongly limited by floral senescence and exacerbated by climate-related stresses.
My PhD therefore aims to identify resilience traits in order to find better-adapted genotypes. A promising lead involves spike architectures and physiological traits that allow for more efficient carbon allocation to developing florets. However, current knowledge on the regulation of spike fertility is fragmented and tends to focus on isolated processes and single climatic factors, which is insufficient to capture the complexity of fertility regulation by both genotype and climate.
The objective of my PhD is thus to adopt an integrated approach to studying the regulation of spike fertility as a function of genotype and climatic conditions. The approach will rely on the theoretical framework of Munch, which posits that carbon allocation to a “sink” organ depends on three fundamental processes: (1) carbon supply from photosynthetic organs, (2) its transport to the sink (here, the floret), and (3) the sink's ability to use it.
My thesis xill be structured around three main axes. The first will explore the impact of unfavorable climatic scenarios on carbon allocation to florets and its consequences on spike fertility. The second axis will investigate how the morphological and physiological traits of the spike—shaped by both climate and genotype—affect carbon supply to florets and their survival. These experimental results will be used to establish a theoretical framework describing fertility regulation by climate and genotype, which will then feed within a third axis into an existing numerical model to simulate different climatic scenarios and identify more resilient spike ideotypes.

Keywords: Allocation du carbone, architecture, fertilité de l’épi, organes puits, stress climatiques.

Supervisors
UMR LEPSE, MAGE Team: Jessica BERTHELOOT (PhD supervisor) , Bertrand MULLER (PhD co-supervisor)