Litchi is valued for its translucent aril, juicy texture, and distinctive fragrance, but aroma remains a difficult quality trait to define and improve. Fruit scent is shaped by many low-molecular-weight volatile organic compounds (VOCs) produced through multiple metabolic pathways. Among them, fatty acid-derived C6 and C9 aldehydes and alcohols often contribute green, crisp, and fresh sensory notes. Although previous studies have described honey-like, osmanthus-like, citrus-like, and fresh aromas in different litchi cultivars, the specific compounds and regulatory genes responsible for the fresh scent were not well understood. Based on these challenges, deeper research into the volatile signatures and regulatory mechanisms shaping fresh aroma in litchi is needed.
Researchers from South China Agricultural University, Guangdong Academy of Agricultural Sciences, China Agricultural University, and Dongguan Agricultural Scientific Research Center published (DOI: 10.1093/hr/uhag010) the study on January 9, 2026, in Horticulture Research. The study reports that the LcARF17/LcRAP2-4–LcLOX7 regulatory module promotes the biosynthesis of fresh-aroma volatiles, especially C9 compounds, in litchi aril, offering new molecular insight into fruit flavor formation.
The team first profiled C6 and C9 volatile compounds in the arils of 24 representative litchi cultivars using gas chromatography–mass spectrometry (GC–MS). Fifteen compounds were detected, and the cultivars were divided into light- and strong-fresh-aroma groups according to volatile profiles. Four compounds showed the strongest ability to separate the two groups and accumulated more strongly during fruit maturation in fresh-aroma cultivars. To link these aroma traits with gene activity, the researchers performed RNA sequencing (RNA-seq), weighted gene co-expression network analysis (WGCNA), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis, and reverse transcription quantitative polymerase chain reaction (RT-qPCR). These analyses identified LcLOX7 as a key candidate associated with fresh-aroma volatile biosynthesis. Functional assays showed that overexpressing LcLOX7 in litchi callus and tomato fruits increased fatty acid-derived VOC production, with a particularly strong effect on C9 volatiles. The study then showed that LcARF17 and LcRAP2-4 directly bind to the LcLOX7 promoter and activate its transcription. Overexpression and silencing experiments confirmed that these two transcription factors (TFs) regulate LcLOX7 expression and C9 volatile emission.
The authors said the study connects what consumers smell in litchi with the molecular switches that help produce that aroma. They said the four identified VOCs provide practical markers for evaluating fresh-aroma intensity, while LcARF17, LcRAP2-4, and LcLOX7 explain how this trait can be regulated during fruit development. They also said the findings give the first evidence that an auxin response factor (ARF) transcription factor participates in fresh fruit aroma formation, opening a new direction for understanding flavor regulation in horticultural crops.
The findings may support more precise flavor-oriented breeding in litchi. Aroma is an important driver of consumer preference, but it is often hard to select for because it depends on complex chemical profiles and developmental regulation. By identifying both aroma compounds and regulatory genes, this study provides a useful framework for screening litchi germplasm, evaluating flavor quality, and developing cultivars with stronger or more desirable fresh-aroma traits. More broadly, the LcARF17/LcRAP2-4–LcLOX7 module offers a model for studying fatty acid-derived aroma formation in other fruit crops, where fresh scent is also central to eating quality and market value.
###
References
DOI
10.1093/hr/uhag010
Original Source URL
https://doi.org/10.1093/hr/uhag010
Funding information
This research was funded by the China Agricultural Research System (CARS-32-05), the National Natural Science Foundation of China (grant numbers 32330092 and 32202447), and the Natural Science Foundation of Guangdong Province (grant numbers 2023A1515012661).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2023. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.