Chemotaxonomy and Palynology of the Citrus Species in Iraq: A Biosystematics Study

Articles in Press

Document Type : Research Article

Authors

Department of Plant Science, Faculty of Basic Science, University of Mazandaran, Babolsar, Iran

Abstract

The Rutaceae family plays an important role in the biodiversity of the ecosystem, as it comprises evergreen species that serves economic, health, and cosmetic purposes, among others. The aim of this study was to conduct a biosystematic investigation of the genus Citrus (Rutaceae) in Iraq using chemotaxonomic and palynological approaches. For this purpose, leaves of eleven Citrus species were collected from Diyala Province, Iraq. Methanolic leaf extracts were analyzed using gas chromatography-mass spectrometry (GC-MS), and pollen morphology was examined using field‑emission scanning electron microscopy (FESEM). GC-MS spectrum analysis of the methanolic extracts of the eleven leaf extracts revealed qualitative and quantitative variation in the detected chemical compounds among the studied species. Hierarchical cluster analysis (HCA) based on the GC–MS data separated the species into two main clusters. The first cluster (C1) includes nine species, C. sinensis, C. reshni, C. aurantium, C. latifolia, C. sinensis var. Moro, C. deliciosa, C. grandis, C. aurantiifolia var. acidica and C. paradisi. The second cluster (C2) included C. limetta and C. limon. Palynological observations showed that the pollen grains of all examined species were unicellular, radially symmetrical, and isopolar. The grains were generally medium‑sized, and their basic shapes included spheroidal to sub‑prolate forms. Minor size variation was observed among species, but no major structural deviations were recorded. Overall, the chemotaxonomic and palynological data were congruent and provided complementary evidence for species delimitation within Citrus. These findings highlight the usefulness of integrating chemical profiling and pollen morphology in biosystematic studies of this genus.

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References

Abo-Elnaga, A. Z., Ali, A. M., & Rabei, S. H. (2018). Pollen morphological variations among some cultivated Citrus species and its related genera in Egypt. Scientific Journal of Agricultural Sciences, 12(1), 163-173. https://doi.org/10.21608/sjdfs.2018.194790
Al-Aamri, M. S., Al-Abousi, N. M., Al-Jabri, S. S., Alam, T., & Khan, S. A. (2018). Chemical composition and in-vitro antioxidant and antimicrobial activity of the essential oil of Citrus aurantifolia L. leaves grown in Eastern Oman. Journal of Taibah University Medical Sciences, 13(2), 108-112. https://doi.org/10.1016/j.jtumed.2017.12.002
Al-Anbari, A. K., Barusrux, S., Pornpongrungrueng, P., & Theerakulpisut, P. (2015). Systematic significance of pollen morphology of Citrus (Rutaceae) from Iraq. Medicinal & Aromatic Plants, 4(3), 1000191. https://doi.org/10.4172/2167-0412.1000191
Anmol, R. J., Marium, S., Hiew, F. T., Han, W. C., Kwan, L. K., Khai, A., Wong, Y., Khan, F., Sarker, M. R., Chan, S. Y., & Kifli, N. (2021). Phytochemical and therapeutic potential of Citrus grandis (L.) Osbeck: A review. Journal of Evidence-Based Integrative Medicine, 26, 1-20. https://doi.org/10.1177/2515690x211043741
Benedetto, N., Carlucci, V., Faraone, I., Lela, L., Ponticelli, M., Russo, D., Mangieri, C., Tzvetkov, N. T., & Milella, L. (2023). An insight into Citrus medica Linn.: A systematic review on phytochemical profile and biological activities. Plants, 12(11), 2150. https://doi.org/10.3390/plants12112150
Bilgin, N., Mısırlı, A., & Güneri, M. (2022). A study on the characterization of Citrus pollen grains. Erwerbs-Obstbau, 64(3), 569-573. https://doi.org/10.1007/s10341-022-00655-0
Deng, H., He, R., Huang, R., Pang, C., Ma, Y., Xia, H., Liang, D., Liao, L., Xiong, B., Wang, X., Zhang, M., Ao, X., Yu, B., Han, D., & Wang, Z. (2022). Optimization of a static headspace GC-MS method and its application in metabolic fingerprinting of the leaf volatiles of 42 Citrus cultivars. Frontiers in Plant Science, 13, 1050289. https://doi.org/10.3390/fpls.2022.1050289
Ding, M., Xie, Q., Jiang, L., Liu, L., Luo, W., Su, H., & Chen, Q. (2024). Pollen morphological characteristics of 46 germplasm resources of Polygonatum and its taxonomic implications. Plants, 13(2), 263. https://doi.org/10.3390/plants13020263
Dutra, F. V., & Gasparino, E. C. (2018). Pollen morphology of Rutaceae from Brazilian forest fragments. Palynology, 42(1), 43-54. https://doi.org/10.1080/01916122.2017.1306812
Elhawary, E. A., Nilofar, N., Zengin, G., & Eldahshan, O. A. (2024). Variation of the essential oil components of Citrus aurantium leaves upon using different distillation techniques and evaluation of their antioxidant, antidiabetic, and neuroprotective effect against Alzheimer’s disease. Industrial Crops and Products, 213, 118435. https://doi.org/10.1016/j.indcrop.2024.118435
Garralla, S. S. (2021). Pollen morphology of the native Rutaceae species from Argentina. Darwiniana, Nueva Serie, 9(2), 282-292. https://doi.org/10.14522/darwiniana.2021.92.962
Húngaro, V., Gusman, B., Soares, E. L., & De Souza, C. N. (2024). Morphological analysis of pollen grains in Machaerium species from São Paulo, Brazil. Acta Botanica Brasilica, 38, e20240042. https://doi.org/10.1590/1677-941X-ABB-2024-0042
Khan, N. H., Qian, C. J., & Perveen, N. (2018). Phytochemical screening, antimicrobial and antioxidant activity determination of Citrus maxima peel. Pharmacy and Pharmacology International Journal, 6(4), 279-285. https://doi.org/10.15406/ppij.2018.06.00187
Lora, J., Garcia-Lor, A., & Aleza, P. (2022). Pollen development and viability in diploid and doubled diploid Citrus species. Frontiers in Plant Science, 13, 862813. https://doi.org/10.3389/fpls.2022.862813
Mohammed, I. O., Alrasheid, A. A., Mohammed, S., & Ayoub, H. (2024). GC-MS analysis and study of the antimicrobial activity of Citrus paradisi, Citrus aurantifolia, and Citrus sinensis peel essential oils as hand sanitizer. Journal of Tropical Medicine, 2024, 4957712. https://doi.org/10.1155/2024/4957712
Owolabi, M. S., Avoseh, O. N., Ogunwande, I. A., William, N., Ogungbo, R., Ogundajo, A. L., Lawal, O. A., & Flamini, G. (2018). Chemical composition of Citrus limon (L.) Osbeck growing in southwestern Nigeria: Essential oil chemotypes of both peel and leaf of lemon. American Journal of Essential Oils and Natural Products, 6(4), 36-40. https://www.essencejournal.com/
Parobali, T., Songuine, T., Yarkoa, T., & Karou, S. D. (2024). Influence of Citrus sinensis seed powder on growth performance, morphological and histological development of the small intestine of broiler chickens. Journal of Applied Poultry Research, 33(2), 100395. https://doi.org/10.1016/j.japr.2023.100395
Posadino, A. M., Maccioccu, P., Eid, A. H., Giordo, R., Pintus, G., & Fenu, G. (2024). Citrus limon var. pompia Camarda var. nova: A comprehensive review of its botanical characteristics, traditional uses, phytochemical profile, and potential health benefits. Plants, 13(13), 1735. https://doi.org/10.3390/plants13131735
Pham, T. L. C., Le, H. T., Nguyen, T. T. H., & Pham, V. H. (2020). Valorization of Citrus leaves: Chemical composition, antioxidant and antibacterial activities of essential oils. Waste and Biomass Valorization, 11(8), 4111-4121. https://doi.org/10.1007/s12649-019-00742-w
Rana, G. M. M., Uddin, J., Barmon, J., Chandra, B., Akter, T., Kumar, A., Maitra, B., Moin, I., Mahbubur, A. H. M., Kanti, B., & Sarmina, M. (2025). Assessment of the essential oil extracted from Citrus aurantifolia leaves using solvent-free microwave extraction technique. Food Chemistry Advances, 6, 100913. https://doi.org/10.1016/j.focha.2025.100913
Rao, M. J., Feng, B., Ahmad, M. H., Tahir, M., Aslam, M. Z., Khalid, M. F., Hussain, S., Zhong, R., Ali, Q., Xu, Q., Ma, C., & Wang, L. (2023). LC-MS/MS-based metabolomics approach identified novel antioxidant flavonoids associated with drought tolerance in Citrus species. Frontiers in Plant Science, 14, 1150854. https://doi.org/10.3389/fpls.2023.1150854
Saidi, S., Handaq, N., Remok, F., Drioiche, A., Bouissane, L., & Zair, T. (2022). Citrus × clementina (leaf): Phytochemical and antioxidant activity. Arabian Journal of Medicinal and Aromatic Plants, 8(1), 87-107. https://revues.imist.ma/index.php/AJMAP/login?source=%2Findex.php%2FAJMAP%2F
Sharma, P., & Singh, A. P. A. L. (2025). Comprehensive review of the pharmacological potential of Citrus reticulata leaves: Evaluating efficacy, safety, and therapeutic potential. International Journal of Research in Pharmaceutical Sciences, 17(5), 17-21. https://ijrps.com/
Zhang, H., Chen, M., Wen, H., Wang, Z., Chen, J., Fang, L., & Zhang, H. (2020). Transcriptomic and metabolomic analyses provide insight into the volatile compounds of citrus leaves and flowers. BMC Plant Biology, 20, 310. https://doi.org/10.1186/s12870-020-02517-5
Zhao, D., Feng, G., Yang, Z., Bi, G., Wei, H., Sun, Y., Chen, L., Yang, Y., Li, W., Li, Y., Li, C., & Yi, H. (2025). Analysis of the pollen morphology and cluster of different pummelo germplasms. Horticulturae, 11(1), 45. https://doi.org/10.3390/horticulturae11010045
Zhao, Y., Xiong, H., Luo, Y., Hu, B., Wang, J., Tang, X., & Rennenberg, H. (2024). Long-term nitrogen fertilization alters the partitioning of amino acids between citrus leaves and fruits. Frontiers in Plant Science, 15, 1516000. https://doi.org/10.3389/fpls.2024.1516000
Journal of Genetic Resources

Articles in Press, Accepted Manuscript
Available Online from 17 July 2026

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