The accumulation pattern of sugars and organic acids in diverse fruit pulps coordinates sweet-sour taste of passion fruit

Passion fruit is highly esteemed for its distinct sweet-sour flavor, a key attribute that largely hinges on the equilibrium between soluble sugars and organic acids. To better understand the sweet-sour flavor formation in P. edulis, we performed comprehensive metabolite profiling through GC-MS and LC-MS analyses, systematically quantifying spatial distributions of soluble sugars and organic acids across pulp tissues in multiple cultivars. Sucrose is concentrated in the pulp neck exerting favorable sweet flavor, while citric acid and L-malic acid accumulate mainly in the pulp body, collectively contributing to the fruit's sweet-sour flavor profile. Integrated transcriptomic analysis combining with WGCNA co-expression networks identified key regulators, PeMYB306, PeNF-YA3 and PeSWEET2A-1, coordinating sugar-acid metabolism in fruit pulp. These findings provide insights into the composition of sugar and organic acid compounds in fine-tuning of flavor of passion fruit pulp, thereby offering a preliminary perspective for the genetic improvement of its sensory qualities.