Harnessing Apple Cell Suspension Cultures in Bioreactors for Triterpene Production: Transcriptomic Insights into Biomass and Triterpene Biosynthesis

Plant cell suspension cultures offer a sustainable method for producing valuable secondary metabolites, such as bioactive pentacyclic triterpenes. This study established a high-triterpene-yielding cell suspension culture from the apple cultivar "Cox Orange Pippin." Through transcriptomic analysis and triterpene profiling across growth phases, we uncovered complex regulatory networks that govern biomass production and triterpene biosynthesis. Key biological processes, including cell cycle regulation, cell wall biosynthesis, lipid metabolism, and stress response mechanisms, play pivotal roles in culture dynamics. Differential gene expression linked to these processes revealed how the culture adapts to growth conditions and nutrient availability at each growth phase. Methyl jasmonate elicitation enhanced phenylpropanoid and flavonoid biosynthesis, along with specific triterpene production pathways, highlighting its potential for optimizing secondary metabolite production. Key enzymes, including oxidosqualene cyclase 4 and a putative C-2a hydroxylase, emerged as promising targets for future metabolic engineering of triterpene pathways. This study represents the first in-depth report on the molecular mechanisms underlying plant cell growth in bioreactors, specially focusing on a non-model plant species . These findings reveal key regulatory pathways in biomass accumulation and triterpene production, offering insights to optimize bioreactor cultures for industrial use. The research opens new avenues to enhance triterpene yields via targeted metabolic engineering and innovative bioprocessing strategies, paving the way for efficient large-scale production. Overall design: A Malus x domestica cell line produced from the Cox orange Pippin variety was grown in bioreactors with three biological replicates. Cells were sampled during the course of the batch to investigate gene expression patterns being involved in the different growth stages (lag phase, exponential phase, stationnary phase, post elicitation)