麻豆传媒

News — Citrus fruits, prized globally for their flavor and health benefits, derive much of their taste appeal from a precise balance of sugars and organic acids. While past studies have mapped the pathways for sugar and acid synthesis, the specific storage mechanisms within vacuoles, where flavor is concentrated, remain less understood. As demand for high-quality citrus increases worldwide, deeper insights into these storage processes are critical. In response to these challenges, comprehensive studies targeting vacuolar transport mechanisms have become essential to enhancing citrus flavor.

The National Key Laboratory for Germplasm Innovation & Utilization of Horticultural Crops at Huazhong Agricultural University led this research, on November 28, 2024, in . By isolating vacuoles from six citrus varieties and using label-free LC-MS/MS proteomic analysis, the team identified core proteins responsible for sugar and acid transport within the fruit. This approach unveils novel tonoplast transporters involved in storing sugar and acid, paving the way for refining flavor quality in citrus production through enhanced metabolic understanding.

Through advanced proteomic techniques, researchers identified 1,443 core proteins within citrus vacuoles, with specific transporters, such as ABCG15, Dict2.1, and STP7, showing key roles in citric acid and sugar accumulation. Notably, the study demonstrated how ABCG15 and Dict2.1 influence citric acid levels, contributing to the acidic profile in certain citrus varieties. Additionally, STP7, TMT2, and ERD6L transporters were linked to sugar levels, significantly enhancing sweetness in varieties like sweet orange and tangerine. These transporters actively manage the storage and balance of sugars and acids, directly shaping fruit taste and quality. To validate these findings, immunoblot assays confirmed the purity of isolated proteins, marking a first for citrus research at this scale and underscoring proteomics’ potential for advancing agricultural practices.

Dr. Chunlong Li, lead researcher, commented, “Our findings mark a promising path for enhancing citrus flavor quality. By isolating the proteins responsible for sugar and acid transport within citrus vacuoles, we gain a deeper grasp of citrus metabolism and open possibilities for genetic enhancement. Identifying transporters like ABCG15 and STP7 offers a valuable tool for breeding strategies aimed at optimizing taste and nutritional value in citrus varieties.”

This research heralds major advancements in citrus breeding. By spotlighting transporters that affect flavor, breeders can now target specific genes tied to these transport proteins to enrich taste profiles. Furthermore, this study sets a foundation for improving quality traits in other crops with similar vacuolar storage. In the future, insights into citrus vacuolar transport mechanisms may drive the development of varieties with enhanced sugar and acid profiles, meeting consumer demand for quality and increasing the economic value of citrus in global markets.

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Funding information

This work was supported by National Key Research and Development Program of China (2022YFF1003100), the National Natural Science Foundation of China (32322073), Foundation of Hubei Hongshan Laboratory (2021hszd016), Fundamental Research Funds for the Central Universities (2662023PY011), and the Huazhong Agricultural University (start-up funding to C. L.).

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is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2022. 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.