{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,9]],"date-time":"2026-06-09T06:04:24Z","timestamp":1780985064250,"version":"3.54.1"},"reference-count":30,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,6,9]],"date-time":"2026-06-09T00:00:00Z","timestamp":1780963200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Plant Sci."],"abstract":"\n Introduction<\/jats:title>\n \n Soluble sugar composition critically determines the commercial quality of loquat (\n Eriobotrya japonica<\/jats:italic>\n ), a prominent Rosaceae fruit. Sucrose synthase (SUS) plays a central role in carbohydrate partitioning and fruit sink strength, yet the SUS gene family in loquat remains uncharacterized.\n <\/jats:p>\n <\/jats:sec>\n \n Methods<\/jats:title>\n \n Seven\n EjSUS<\/jats:italic>\n genes were identified from the loquat genome and analyzed via phylogenetics, chromosomal mapping, synteny, and structural characterization. Spatiotemporal expression profiling was performed during fruit development in two cultivars (\u2018YingShuang\u2019 and \u2018ZheHong 16\u2019). Soluble sugar contents were measured, and Pearson correlation analysis was conducted. Recombinant\n EjSUS4<\/jats:italic>\n protein was subjected to in vitro enzymatic assays. Promoter cis-element analysis was also performed.\n <\/jats:p>\n <\/jats:sec>\n \n Results<\/jats:title>\n \n The seven\n EjSUS<\/jats:italic>\n genes were classified into three subfamilies. Segmental and tandem duplications drove family expansion.\n EjSUS4<\/jats:italic>\n (Group I) was specifically and highly upregulated during the terminal ripening stage, coinciding with peak sucrose accumulation, whereas other\n EjSUS<\/jats:italic>\n members showed very low or undetectable expression. Loquat was confirmed as a hexose-accumulating fruit.\n EjSUS4<\/jats:italic>\n transcript levels showed a highly significant positive correlation with sucrose content. Recombinant\n EjSUS4<\/jats:italic>\n exhibited robust sucrose synthesis activity, and its promoter contained ABRE cis-elements potentially linking it to ABA signaling.\n <\/jats:p>\n <\/jats:sec>\n \n Discussion<\/jats:title>\n \n Our findings demonstrate that\n EjSUS4<\/jats:italic>\n is the predominant SUS member driving late-stage sugar accumulation in loquat. This work provides valuable genetic resources and a theoretical basis for molecular breeding to improve loquat fruit quality.\n <\/jats:p>\n <\/jats:sec>","DOI":"10.3389\/fpls.2026.1860539","type":"journal-article","created":{"date-parts":[[2026,6,9]],"date-time":"2026-06-09T05:43:27Z","timestamp":1780983807000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Sucrose synthase gene family analysis in loquat reveals EjSUS4 as a key regulator of sugar accumulation"],"prefix":"10.3389","volume":"17","author":[{"given":"Junhao","family":"Yan","sequence":"first","affiliation":[{"name":"College of Horticulture, Zhejiang A&F University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wenqi","family":"Shao","sequence":"additional","affiliation":[{"name":"College of Horticulture, Zhejiang A&F University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jie","family":"Ding","sequence":"additional","affiliation":[{"name":"College of Horticulture, Zhejiang A&F University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Minghui","family":"Chen","sequence":"additional","affiliation":[{"name":"College of Horticulture, Zhejiang A&F University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chaofeng","family":"Yang","sequence":"additional","affiliation":[{"name":"State Key Laboratory for Development and Utilization of Forest Food Resources, Zhejiang A&F University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kai","family":"Xu","sequence":"additional","affiliation":[{"name":"College of Horticulture, Zhejiang A&F University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Boping","family":"Wu","sequence":"additional","affiliation":[{"name":"College of Horticulture, Zhejiang A&F University","place":["Hangzhou, Zhejiang, China"]},{"name":"State Key Laboratory for Development and Utilization of Forest Food Resources, Zhejiang A&F University","place":["Hangzhou, Zhejiang, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,6,9]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.3390\/molecules23051144","article-title":"The sucrose synthase gene family in Chinese pear (Pyrus bretschneideri Rehd.): structure, expression, and evolution","volume":"23","author":"Abdullah","year":"2018","journal-title":"Molecules"},{"key":"B2","doi-asserted-by":"publisher","DOI":"10.3389\/fpls.2022.1039360","article-title":"Sugar and acid profile of loquat (Eriobotrya japonica Lindl.), enzymes assay and expression profiling of their metabolism-related genes as influenced by exogenously applied boron","volume":"13","author":"Ali","year":"2022","journal-title":"Front. 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