Wu Die

PhD student
in Plant Ecophysiology and Physiology

Team: ETAP

I received my MSc in Cell Biology from the University of the Chinese Academy of Sciences in 2024, with a focus on cell and molecular biology.
Since October 2024, I have been a PhD student at LEPSE in the ETAP team, studying the determinism of the LowSugarBerry (LSB) trait and its potential advantages for acclimation to water deficit.

Start of PhD: 1.10.2024

Subject: Physiological and transcriptional determinism of the LowSugarBerry trait and its impacts on the
performance of the vine under water deficit

Abstract
New grapevine varieties displaying low sugar concentration in berries (LowSugarBerry, LSB) and resistant to mildews could make vineyards both more resilient to climate change (global warming, drought) and less reliant on chemicals. The objective of this thesis is to compare carbon metabolism and water balance responses between LSB and non-LSB grapevine varieties subjected to water deficit, and elucidate the physiological, structural and transcriptomic origins of the LSB trait. In order to address these objectives, two main hypotheses were proposed: (i) the decoupling of water vs carbon imports into LSB fruits results from properties of the pericarp cell walls which allow berry expansion at low osmotic gradient, and (ii) at equivalent fruit water budget, the lower sugar fruit demand favors a more comfortable carbon status of the vine under water deficit.
To test these hypotheses, a combination of phenotyping approaches is performed to both LSB and non-LSB macrovines and microvines grown in different environments including growth chambers and phenotyping platforms (greenhouse and field trials). These approaches will be used to assess: (i) the carbon gain and the water loss at the leaf, fruit and whole plant levels, (ii) the rheology of the berries in relation to the composition and anatomical characteristics of cell wall structures of the berry skin and pulp, and (iii) the identification of differentially expressed genes (DEGs) associated with functional categories and (iso)genes co-regulated with the LSB trait in berries. Overall, this work is expected to advance the understanding of the mechanisms underlying berry sugar and water accumulation and to provide scientific bases for breeding grapevine varieties better adapted to future climatic constraints.

Key words: Cell wall, LowSugarBerry (LSB), transcriptomics, Water deficit.

Publication

Bigard A, de Almeida LW, Berhe DT, Wu D, Ojeda H, Pellegrino A, Romieu C, and Torregrosa L (2025) The LowSugarBerry trait phenotyped at single fruit and population levels. BMC Research Notes, 18:236. doi:  10.1186/s13104-025-07289-x

Supervisors
UMR LEPSE, ETAP Team: Anne Pellegrino (PhD supervisor), Laurent Torregrosa (PhD co-supervisor)
UMR SPO : Charles Romieu (PhD co-supervisor)