{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T12:47:33Z","timestamp":1792068453603,"version":"4.4.0"},"reference-count":33,"publisher":"SAGE Publications","license":[{"start":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T00:00:00Z","timestamp":1791763200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"funder":[{"DOI":"10.13039\/501100001695","name":"Japan Science and Technology Corporation","doi-asserted-by":"publisher","award":["Sakura Science Program"],"award-info":[{"award-number":["Sakura Science Program"]}],"id":[{"id":"10.13039\/501100001695","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP21H04781"],"award-info":[{"award-number":["JP21H04781"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP23H04965"],"award-info":[{"award-number":["JP23H04965"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001691","name":"Japan Society for the Promotion of Science","doi-asserted-by":"publisher","award":["JP23H04966"],"award-info":[{"award-number":["JP23H04966"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["J Biol Rhythms"],"abstract":"<jats:p>\n                    Circadian rhythms allow plants to regulate internal processes to align with daily rhythms in the environment. Comparing circadian clocks across environments is essential because latitude-dependent variation in light and temperature imposes distinct selection pressures that shape the evolution and function of circadian timing systems. However, circadian clock studies have largely focused on temperate and subtropical species, leaving transcriptional circadian networks in tropical plants poorly understood. We report the comprehensive circadian transcriptome of\n                    <jats:italic toggle=\"yes\">Rubroshorea leprosula<\/jats:italic>\n                    , a dominant species in tropical rainforests in Southeast Asia. One sapling was sampled every 4 hours over 48-hour period under constant darkness and used for transcriptomic analyses. Only 283 of 20\u2009748 expressed genes (~1.3%) exhibited significant circadian oscillations, with periods strongly concentrated between 23 and 25 hours. Hierarchical clustering revealed 4 temporal clusters with alternate phases of expression and functional specialization. Comparative analysis identified clear orthologs for all major\n                    <jats:italic toggle=\"yes\">Arabidopsis<\/jats:italic>\n                    circadian clock components, with conserved synteny to\n                    <jats:italic toggle=\"yes\">Parashorea chinensis<\/jats:italic>\n                    , a close relative of\n                    <jats:italic toggle=\"yes\">R leprosula<\/jats:italic>\n                    . Time-lagged cross-correlation network reconstruction identified a characteristic circadian topological similarity with\n                    <jats:italic toggle=\"yes\">Arabidopsis<\/jats:italic>\n                    , including coupled morning and evening feedback loops and paralog expansion that maintained overall structure. Peak expression timing of these core clock genes in the tropical tree was largely consistent with that observed in\n                    <jats:italic toggle=\"yes\">Arabidopsis thaliana<\/jats:italic>\n                    . In contrast,\n                    <jats:italic toggle=\"yes\">Rubroshorea<\/jats:italic>\n                    orthologs showed reduced amplitudes and lower coefficients of variation under this single constant darkness, single-individual condition; because dark-induced damping is common across plants, this pattern is consistent with, but does not establish, reduced circadian robustness in\n                    <jats:italic toggle=\"yes\">R leprosula<\/jats:italic>\n                    linked to tropical adaptation. This study lays the molecular foundation for circadian regulation in dipterocarps and offers a system for integrating rhythmic gene expression to ecological function and forest productivity in tropical communities.\n                  <\/jats:p>","DOI":"10.1177\/07487304261488074","type":"journal-article","created":{"date-parts":[[2026,10,12]],"date-time":"2026-10-12T10:40:08Z","timestamp":1791801608000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":0,"title":["Circadian Timekeeping in the Tropics: Rhythmic Transcriptome and Diurnal Regulatory Networks in\n                    <i>Rubroshorea leprosula<\/i>"],"prefix":"10.1177","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-3179-7599","authenticated-orcid":false,"given":"Shashank Kumar","family":"Singh","sequence":"first","affiliation":[{"name":"Department of Biological Sciences and Engineering, Indian Institute of Technology Gandhinagar, India"},{"name":"Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Motohide","family":"Seki","sequence":"additional","affiliation":[{"name":"Faculty of Design, Kyushu University, Fukuoka, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hiroshi","family":"Ito","sequence":"additional","affiliation":[{"name":"Faculty of Design, Kyushu University, Fukuoka, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Naoki","family":"Tani","sequence":"additional","affiliation":[{"name":"Forestry Division, Japan International Research Center for Agricultural Sciences, Tsukuba, Japan"},{"name":"Institute of Life and Environmental Sciences, University of Tsukuba, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yuka","family":"Ikezaki","sequence":"additional","affiliation":[{"name":"Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kayoko","family":"Ohta","sequence":"additional","affiliation":[{"name":"Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Suat Hui","family":"Yeoh","sequence":"additional","affiliation":[{"name":"Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ng","family":"Ching Ching","sequence":"additional","affiliation":[{"name":"Institute of Biological Sciences, Faculty of Science, University of Malaya, Kuala Lumpur, Malaysia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Akiko","family":"Satake","sequence":"additional","affiliation":[{"name":"Department of Biology, Faculty of Science, Kyushu University, Fukuoka, Japan"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2026,10,12]]},"reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.1115581"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1007\/s10265-017-0991-8"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1007\/s11103-016-0477-4"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1038\/nrg3976"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-019-08398-5"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.3390\/genes11111284"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1098\/rspb.2022.0577"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1111\/pce.14297"},{"key":"e_1_3_2_10_2","doi-asserted-by":"publisher","DOI":"10.1177\/0748730408316040"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1073\/pnas.1307701110"},{"key":"e_1_3_2_12_2","doi-asserted-by":"publisher","DOI":"10.1146\/annurev-arplant-070522-065329"},{"key":"e_1_3_2_13_2","doi-asserted-by":"publisher","DOI":"10.1007\/s12042-008-9020-3"},{"key":"e_1_3_2_14_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-313X.2006.02847.x"},{"key":"e_1_3_2_15_2","doi-asserted-by":"publisher","DOI":"10.1007\/978-3-662-07255-4_20"},{"key":"e_1_3_2_16_2","doi-asserted-by":"publisher","DOI":"10.1086\/284837"},{"key":"e_1_3_2_17_2","doi-asserted-by":"publisher","DOI":"10.2307\/2656924"},{"key":"e_1_3_2_18_2","doi-asserted-by":"publisher","DOI":"10.1111\/1365-2745.12836"},{"key":"e_1_3_2_19_2","doi-asserted-by":"publisher","DOI":"10.1038\/s42003-022-03245-8"},{"key":"e_1_3_2_20_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1751-1097.1964.tb08171.x"},{"key":"e_1_3_2_21_2","doi-asserted-by":"publisher","DOI":"10.1111\/mec.14257"},{"key":"e_1_3_2_22_2","doi-asserted-by":"publisher","DOI":"10.1093\/bioinformatics\/bty560"},{"key":"e_1_3_2_23_2","doi-asserted-by":"publisher","DOI":"10.1093\/bioinformatics\/bts635"},{"key":"e_1_3_2_24_2","doi-asserted-by":"publisher","DOI":"10.7554\/eLife.88456"},{"key":"e_1_3_2_25_2","doi-asserted-by":"publisher","DOI":"10.1186\/1471-2105-12-323"},{"key":"e_1_3_2_26_2","doi-asserted-by":"publisher","DOI":"10.1093\/bioinformatics\/btp616"},{"key":"e_1_3_2_27_2","doi-asserted-by":"publisher","DOI":"10.1177\/0748730414553029"},{"key":"e_1_3_2_28_2","doi-asserted-by":"publisher","DOI":"10.1177\/0748730410379711"},{"key":"e_1_3_2_29_2","doi-asserted-by":"publisher","DOI":"10.1093\/bioinformatics\/btl567"},{"key":"e_1_3_2_30_2","doi-asserted-by":"publisher","DOI":"10.1016\/j.xplc.2022.100464"},{"key":"e_1_3_2_31_2","doi-asserted-by":"publisher","DOI":"10.1101\/sqb.2007.72.006"},{"key":"e_1_3_2_32_2","doi-asserted-by":"publisher","DOI":"10.1111\/j.1365-313X.2011.04505.x"},{"key":"e_1_3_2_33_2","doi-asserted-by":"publisher","DOI":"10.1007\/s11103-024-01493-2"},{"key":"e_1_3_2_34_2","doi-asserted-by":"publisher","DOI":"10.1093\/nar\/gkad658"}],"container-title":["Journal 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