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Background Plants have evolved a panoply of specialized metabolites that increase their environmental fitness. Two examples are caffeine, a purine psychotropic alkaloid, and crocins, a group of glycosylated apocarotenoid pigments. Both classes of compounds are found in a handful of distantly related plant genera (Coffea, Camellia, Paullinia, and Ilex for caffeine; Crocus, Buddleja, and Gardenia for crocins) wherein they presumably evolved through convergent evolution. The closely related Coffea and Gardenia genera belong to the Rubiaceae family and synthesize, respectively, caffeine and crocins in their fruits. Results Here, we report a chromosomal-level genome assembly of Gardenia jasminoides, a crocin-producing species, obtained using Oxford Nanopore sequencing and Hi-C technology. Through genomic and functional assays, we completely deciphered for the first time in any plant the dedicated pathway of crocin biosynthesis. Through comparative analyses with Coffea canephora and other eudicot genomes, we show that Coffea caffeine synthases and the first dedicated gene in the Gardenia crocin pathway, GjCCD4a, evolved through recent tandem gene duplications in the two different genera, respectively. In contrast, genes encoding later steps of the Gardenia crocin pathway, ALDH and UGT, evolved through more ancient gene duplications and were presumably recruited into the crocin biosynthetic pathway only after the evolution of the GjCCD4a gene. Conclusions This study shows duplication-based divergent evolution within the coffee family (Rubiaceae) of two characteristic secondary metabolic pathways, caffeine and crocin biosynthesis, from a common ancestor that possessed neither complete pathway. These findings provide significant insights on the role of tandem duplications in the evolution of plant specialized metabolism.

BackgroundInfectious mononucleosis (IM) is an infectious clinical entity commonly seen in adolescence and early adulthood. It is caused in the majority of cases by Epstein-Barr virus (EBV) and it presents as pharyngitis, fever, and lymphadenopathy. As the viruses mainly target the lymphocytes and reticuloendothelial system of the body, leading to the proliferation of the lymphatic tissues, it is often mistaken as lymphoma. Most cases of IM can be easily distinguished from lymphoma by clinical presentations and laboratory findings. However, atypical clinical presentations or laboratory findings occasionally occur, including the ages of patients over 30, generalized or isolated lymphadenopathy at unusual sites, negative heterophile antibody tests, absence of atypical lymphocytosis in the peripheral blood smear, etc. These atypical cases may lead to confused diagnosis. Therefore, IM should be differentiated from malignant lymphoma. In this paper, we reported a case of atypical IM in the cervical region of an adult, with elder age and longer disease course than typical IM.Case presentationIn this paper, we reported a case of IM in the cervical region of a 31-year-old man, and reviewed the recent literatures on the pathogenesis, as well as differential diagnosis of IM.ConclusionWhen facing enlarged tonsil or cervical lymph nodes, the pathologists should increase vigilance to the differential diagnosis between infectious diseases and lymphomas. Especially in ambiguous cases, it is essential to test for EBER by in situ hybridization to rule out IM before making a preliminary diagnosis of lymphoma.

The evaluation of the soil contaminated by heavy metals can help to judge whether the soil meets the standard and whether the pollution will threaten human health and the ecological environment. In this study, the farmland soil from eight districts in Beijing was used as the research object, and the concentration of heavy metal elements, Pb, As and Cd in the soils and agricultural products were analyzed. The analysis results showed that: (1) The evaluation based on the improved Hakanson method suggested that the crops exhibit a significantly higher ability to absorb Cd than to absorb Pb and As. Pb, As and Cd are all at normal level of ecological risk; among them, Cd is mainly in a moderate ecological risk, without strong ecological risk. (2) Based on the Improved analytic hierarchy process(AHP) of evaluation, 0.2317 is the average value of the integrated index of heavy metal pollution of soil in the study area, which is a mild level of pollution. (3) Through the calculation of various parameters in the Influence index of comprehensive quality(IICQ) of soil and agricultural products, it was found that 0＜IICQS＜1, suggesting that the environmental quality of soil is at a clean level. In summary, the pollution of heavy metals Pb, As and Cd in the farmland soils and crops in the eight districts of Beijing, including Fangshan, Daxing, Shunyi, and Shijingshan is at a low level, and no significant impact has been brought to the surrounding environment.