FranceCountry of destination:
Flowering in apple is the main process that determines yield and a negative relationship between fruit development and floral induction that can lead to biennial bearing in apple has been observed. In this species, both the competition for carbohydrates between developing reproductive and vegetative organs and hormonal signals coming from seeds are suspected to inhibit floral induction. In this project, I aim at complementing the existing functional structural apple tree model MappleT by simulating the transport of both carbohydrates and hormones within a network of organs mixing sources (leaves and seeds producing carbohydrates and hormones respectively) and target organs (terminal meristem) in which flower induction will occur. I expect from such an approach, to test different assumptions regarding the respective impact of hormonal control, nutritional status and tree architecture on floral induction. This approach will include development of a framework for modelling the genetic network regulation involved in floral induction, allowing future knowledge on floral induction regulation to be easily incorporated. Modelling complex tree architectures and intertwined physiological processes requires specific computational methods and mathematical formalisms that are developed in laboratories specialized in computer sciences. Joining the Biological Information Technology team at the University of QueensLand will provide me a unique opportunity to develop this modelling approach on floral induction and to acquire new skills in computational science in order to complement my skills in ecophysiology and plant modelling. The University of Queensland has also a strong expertise in plant physiology especially on hormonal signaling that could be particularly relevant for my research project. Moving to the Biological Information team at the University of Queensland will allow me to acquire new skills in computer science in order to complement my skills in ecophysiology, plant physiology and plant modelling. The long term stay in Australia will be a unique opportunity for me to integrate the international plant modelling community and may also facilitate future international cooperation with other research groups
I am a plant scientist with a PhD in plant integrative biology and applied mathematics (September 2009, Ecole central de Paris, INRA Montpellier). During my PhD I built new models to simulate grapevine growth under stressful environments (water stress, low radiation) and contrasted crop loads. After my doctoral studies, I became assistant lecturer in ecophysiology and plant modelling at Montpellier SupAgro and I developed research activities in collaboration with CIRAD in ecophysiology and modelling on the phenotypic plasticity of oil palm. I was recruited as a young scientist on a permanent position at INRA in 2013 on functional structural modelling of apple tree growth and architecture. I got the opportunity to work at the University of Queensland during one year and a half thanks to AgreenSkills (2015-2016). During this period I developed new models dealing with long-distance fluxes (hormonal and carbon fluxes) that determine floral induction within the tree structure and among years. This modelling work opened the way through new research activities in my French research lab on the main physiological and genetics determinisms of biennial bearing pattern in apple trees.
Pallas B, Bluy S, Ngao J, Martinez S, Clément-Vidal A, Kelner JJ, Costes E., 2018. Growth and carbon balance are differently regulated by tree and shoot fruiting context: an integrative study on apple genotypes with contrasted bearing pattern. Tree Physiology. Doi:10.1093/treephys/tpx166.
Yang W. (Co-first author), Pallas B. (Co-first author), Durand J.-B., Martinez S., Han M., Costes E., 2016. The impact of long-term water stress on tree architecture is related to changes in transitions between vegetative and reproductive growth in the ‘Granny Smith’ apple cultivar. Tree Physiology, 36: 1369-1381.
Pallas B, Da Silva D, Valsesia P, Yang W, Guillaume O, Lauri P-E, Vercambre G, Génard M, Costes E., 2016. Simulation of carbon allocation and organ growth variability in apple tree by connecting architectural and source-sink models. Annals of Botany, 118(2): 317-330.
Pallas B, Clément-Vidal A, Rebolledo MC, Soulié JC, Luquet D., 2013. Using plant growth modelling to analyze C source-sink relations under drought: inter and intra specific comparison. Frontiers in Plant Science 4: 437.
Pallas B, Loi C, Christophe A, Cournède PH, Lecoeur J., 2011. Comparison of three approaches model grapevine organogenesis in conditions of fluctuating temperature, solar radiation and soil water content. Annals of Botany 107: 729-745.