Assessing Dynamic Changes of Taste-Related Primary Metabolism During Ripening of Durian Pulp Using Metabolomic and Transcriptomic Analyses.

Durian is an economically important fruit of Southeast Asia. There is, however, a lack of in-depth information on the alteration of its metabolic networks during ripening. Here, we annotated 94 ripening-associated metabolites from the pulp of durian cv. Monthong fruit at unripe and ripe stages, using capillary electrophoresis- and gas chromatography- time-of-flight mass spectrometry, specifically focusing on taste-related metabolites. During ripening, sucrose content increased. Change in raffinose-family oligosaccharides are reported herein for the first time. The malate and succinate contents increased, while those of citrate, an abundant organic acid, were unchanged. Notably, most amino acids increased, including isoleucine, leucine, and valine, whereas aspartate decreased, and glutamate was unchanged. Furthermore, transcriptomic analysis was performed to analyze the dynamic changes in sugar metabolism, glycolysis, TCA cycle, and amino acid pathways to identify key candidate genes. Taken together, our results elucidate the fundamental taste-related metabolism of durian, which can be exploited to develop durian metabolic and genetic markers in the future.

Genome-wide analysis of the Dof gene family in durian reveals fruit ripening-associated and cultivar-dependent Dof transcription factors.

DNA binding with one finger (Dof) proteins constitute a ubiquitous plant-specific transcription factor (TF) family associated with diverse biological processes, including ripening. We conducted a genome-wide analysis of durian (Durio zibethinus Murr.) and identified 24 durian Dofs (DzDofs), 15 of which were expressed in fruit pulp. Gene expression analysis revealed differential expression of DzDofs during ripening in two commercial durian cultivars from Thailand, Monthong and Chanee. Comparing the expression levels of fruit pulp-expressed DzDofs between cultivars revealed ten potential cultivar-dependent Dofs, among which DzDof2.2 showed a significantly greater fold increase at every ripening stage in Chanee than in Monthong. The prediction of DzDof2.2's function based on its orthologue in Arabidopsis revealed its possible role in regulating auxin biosynthesis. We observed significantly higher auxin levels during ripening of Chanee than Monthong which concurred with the greater expression of auxin biosynthetic genes. Transient expression of DzDof2.2 in Nicotiana benthamiana significantly upregulated the expression levels of auxin biosynthetic genes. Higher expression levels of DzDof2.2 in Chanee would enhance auxin levels through transcriptional regulation of auxin biosynthetic genes. Higher auxin levels in Chanee could activate auxin-mediated transcription, contributing to its faster ripening compared to Monthong through earlier initiation of the ethylene response (auxin-ethylene crosstalk).

Metabolic variation in the pulps of two durian cultivars: Unraveling the metabolites that contribute to the flavor.

Durian (Durio zibethinus M.) is a major economic fruit crop in Thailand. In this study, two popular cultivars, namely Chanee and Mon Thong, were collected from three orchards located in eastern Thailand. The pulp metabolome, including 157 annotated metabolites, was explored using capillary electrophoresis-time of flight/mass spectrometry (CE-TOF/MS). Cultivars and harvest years had more impact on metabolite profile separation than cultivation areas. We identified cultivar-dependent metabolite markers related to durian fruit quality traits, such as nutritional value (pyridoxamine), odor (cysteine, leucine), and ripening process (aminocyclopropane carboxylic acid). Interestingly, durian fruit were found to contain high amounts of γ-glutamylcysteine (810.3 ±â€¯257.5 mg/100 g dry weight) and glutathione (158.1 ±â€¯80.4 mg/100 g dry weight), which act as antioxidants and taste enhancers. This metabolite information could be related to consumer preferences and exploited for durian fruit quality improvement.