Lipid Profiling of Four Guava Cultivars: A Multi-Dimensional Spatial Analysis

This study aimed to reveal the lipid composition and distribution and characterize the lipid metabolism profile in the three distinct parts of four guava varieties with varying textures and colors using liquid chromatography-electrospray ionization-tandem mass spectrometry. The four varieties, collected from a guava cultivation base in Danzhou City, Hainan Province, were "Zhenzhu" (white-fleshed hard-crispy guava, YBSL), "Bendi" (white-fleshed soft-waxy guava, RBSL), "Xiguahong" (red-fleshed hard-crispy guava, YHSL), and "Hongxin" (red-fleshed soft-waxy guava, RHSL). A total of 8242 lipids were detected, which were classified into four categories and 20 subcategories. Glycerolipids and glycerophospholipids are the most abundant types of lipids in guava. The lipid composition showed significant differences between hard-crispy and soft-waxy guavas. The red-fleshed guava varieties had 98, 57, and 96 differential lipid metabolites, whereas white-fleshed varieties had 68, 108, and 41 lipid metabolites in the epicarp, mesocarp, and endocarp, respectively. Moreover, comparative analysis of hard-crispy versus soft-waxy guavas with different colors revealed common differential lipids in the epicarp (29), mesocarp (21), and endocarp (18). The common differential lipids, including phosphatidylcholine (PC) (16:0/18:1), PC (18:1/18:1), and phosphatidylethanolamine (PE) (18:1/18:2), were found to be upregulated across all fruit parts, with greater abundance in soft-waxy guavas. They were mainly enriched in metabolic pathways associated with glycerophosphocholine and glycerophosphoethanolamine. These differential lipids may serve as potential biomarkers for evaluating guava quality. This study unveiled the lipid distribution and metabolic variations among different guava varieties. It also established a scientific foundation for improving guava varieties and implementing quality control measures.