Citrus aurantium L. extract alleviate depression by inhibiting gut microbiota-mediated inflammation in mice

Gut microbiota plays a crucial role in the pathophysiology of depression.This study aimed to explore the antidepressant effect of mature whole Citrus aurantium fruit extract(FEMC)in the chronic unpredictable mild stress(CUMS)model.The behavioral tests were applied to assess antidepressant effect and 16S rRNA sequencing was used to analyze the changes of gut microbiota.The results showed that the major components of FEMC were naringin and neohesperidin and significantly increased the sucrose preference index of the mice.FEMC also could reduce the feeding latency in an open field test and the rest time in a novelty suppressed feeding test.In addition,FEMC could increase CUMS-induced reduction in the levels of BDNF,PSD95,and SYN in the hippocampus.Moreover,FEMC intervention slightly decreased the ratio of Firmicutes to Bacteroidota.Meanwhile,FEMC reduced the abundance of the Prevotellaceae_Ga6A1_group,[Ruminococcus]_torques_group,which have been reported to be closely related to inflammation.Bioinformatics analysis revealed that mitogen-activated protein kinase(MAPK)signaling pathway and lipopolysaccharide biosynthesis were involved in the anti-inflammatory effect of FEMC in the CUMS animal model.Finally,the ELISA results showed that FEMC could significantly reduce the expression of pro-inflammatory cytokines IL-6 and TNF-αin the serum of depressive mice.Our results suggest FEMC can am eliorate depressive behavior by i nhibiting gut microbiota-mediated inflammation in mice.

Protective Effect of Immaturue Bitter Orange(Citrus aurantium L.)Flavonoids Extracts on PC12 Cell Injury Induced by 6-Hydroxydopamine

To study the neuro protective effect of flavonoids extracts from immature bitter orange(Citrus aurantium L.),the PC12 cells treated with 6-hydroxydopamine(6-OHDA)were used as the Parkinson’s disease(PD)model.To determine the optimal dose of 6-OHDA for constructing a PD model,PC12 cells were incubated with different concentrations of 6-OHDA for 24 h.After 24 h incubation,PC12 cells of drug groups were added 6-OHDA and different concentrations of flavonoids extracts were measured cell viability by CCK8 for selecting effective concentration of flavonoids extracts;the ROS level was determined using flow cytometry;the levels of MDA,CAT,SOD and GSH-Px were assayed by Colorimetric kit for oxidative stress investigation.Compared with the model group,PC12 cell viability was significantly enhanced(P<0.05),the levels of ROS and MDA were reduced significantly(P<0.05),and the activities of SOD,CAT and GSH-Px were significantly enhanced(P<0.05)in drug groups.In conclusion,immature bitter orange flavonoids extracts could protect PC12 cells against 6-OHDA-induced oxidative stress.

Expressing p20 hairpin RNA of Citrus tristeza virus confers Citrus aurantium with tolerance/resistance against stem pitting and seedling yellow CTV strains

The Citrus tristeza virus (CTV) uses 3 silencing suppressor genes, p20, p23 and p25, to resist the attacks from its Citrus hosts. Inactivating these genes is therefore obviously a potential defensive option in addition to the current control strat-egies including aphid management and the use of mild strain cross protection. In this study, we cloned partial DNA frag-ments from the three genes, and used them to construct vectors for expressing hairpin RNAs (hpRNAs). To facilitate the formation of hpRNAs, the constructs were introduced in a loop structure. Fol owing transformation of sour orange (Citrus aurantium) with these constructs, 8 p20 hpRNA (hp20) and 1 p25 hpRNA (hp25) expressing lines were obtained. The 7 hp20 transgenic lines were further characterized. Their reactions to CTV were tested fol owing inoculation with CT14A and/or TR-L514, both of which are severe strains. Results showed that 3 lines (hp20-5, hp20-6 and hp20-8) were completely resistant to TR-L514 under greenhouse conditions for no detectable viral load was found in their leaves by PCR. However, they exhibited only partial suppression of TR-L514 under screen house conditions since the virus was detected in their leaves, though 2 months later compared to non-transgenic controls. Further tests showed that hp20-5 was tolerant also to CT14A under screen house conditions. The growth of hp20-5 was much better than others including the controls that were concurrently chal enged with CT14A. These results showed that expressing p20 hpRNA was sufifcient to confer sour orange with CTV resistance/tolerance.

Protective effects of a polymethoxy flavonoids-rich Citrus aurantium peel extract on liver fibrosis induced by bile duct ligation in mice

Objective: To evaluate the possible protective effect of Citrus aurantium peel extract(CAE) against apoptosis in cholestatic liver fibrosis induced by bile duct ligation in mice. Methods: Male ICR mice were divided to 5 groups: 1) Control group(Sham-operated mice), 2) Cholestatic liver injury group induced by bile duct ligation(BDL), 3) BDL mice treated with silymarin(200 mg/kg) for 4 weeks, 4) BDL mice treated with 50 mg/kg CAE for 4 weeks, 5) BDL mice treated with 200 mg/kg CAE for 4 weeks. Mice were sacrificed and liver fibrosis was evaluated by serum and hepatic tissue biochemistry tests and liver histopathological examination. Effects of CAE on inflammation and apoptosis gene regulation were investigated through real-time PCR. CAE effect on lipid metabolism related signaling was determined by western blot analysis. Results: In BDL mice, administration of CAE for 4 weeks markedly attenuated liver fibrosis based on histopathological alteration. Serum and hepatic tissue biochemistry results revealed that CAE(50 and 200 mg/kg) decreased the levels of alanine transaminase, aspartate transaminase, gamma glutamyl transferase, total bilirubin, nitric oxide, and thiobarbituric acid reactive substances. Real-time PCR and western blot analysis showed that CAE regulated inflammation, apoptosis, and lipid metabolism factors increased by BDL. Interleukin family, tumor necrosis factor α, and related apoptosis factors m RNA levels were increased by BDL treatment. However, these increases were suppressed by CAE administration. In addition, CAE effectively increased phosphorylation of AMPactivated protein kinase, nuclear factor E2-related factor 2, and related cytoprotective proteins. Conclusions: CAE can efficiently regulate BDL-induced liver injury with antioxidant, antiinflammatory, and antiapoptotic activities.

Effect of <i>Citrus aurantium</i>L. Essential Oil and Its Interaction with Fluoxetine on Anxiety in Male Mice

Anxiety is a very common mental disorder among neurological diseases. Some herbs have soothing effects and play an important role in reducing anxiety. The purpose of this study is to investigate the effect of Citrus aurantium L. essential oil on anxiety and its interference with serotonergic pathway. Sixty male mice were assigned into control, sham (saline and olive oil), and experimental groups. Intraperitoneal injection of Citrus aurantium L. essential oil was applied at doses of 0.5, 2.5, and 5 percent for 5 days. In another set of experiments, after intraperitoneal injection of Citrus aurantium L. essential oil at doses of 0.5, 2.5, and 5 percent for 5 days, on the 5th day, 30 minutes before applying essential oil, fluoxetine (2 mg/kg) was injected. Then, the anxiety-related behavior was assessed using elevated plus maze test. The results revealed that injection of essential oil of Citrus aurantium L. alone or along with fluoxetine led to increasing the number of entries into the open arms and the time spent in open arms that was significantly different compared with control and sham groups (P?< 0.001). Besides, further effects revealed when fluoxetine added to essential oils, however no more effects obtained when compared to fluoxetine alone. It is concluded that Citrus aurantium L. essential oil can reduce the anxiety in male mice and due to fluoxetin potentiation and maximum response observed, the herb may express its anxiolytic effects in part, via serotonergic system.

基于UPLC特征图谱和多成分定量评价不同采收时间枸橘药材质量

目的:基于不同采收时间枸橘药材UPLC特征图谱,结合黄酮类和香豆素类成分的含量测定,明确枸橘成分积累规律,为枸橘的采收和质量控制提供依据。方法:采用UPLC法构建30批枸橘特征图谱,采用相似度评价、聚类分析、主成分分析和正交偏最小二乘判别分析对数据进行处理。采用HPLC法测定其中6个成分的含量。结果:30批样品UPLC特征图谱共标定25个共有峰,相似度为0.913~0.993,指认了7个成分,其中6个成分芸香柚皮苷、柚皮苷、枸橘苷、欧前胡素、异欧前胡素、葡萄内酯的含量分别为0.62~2.40 mg/g、5.75~27.52 mg/g、7.00~53.86 mg/g、0.63~2.94 mg/g、0.11~0.45 mg/g、3.69~9.29 mg/g;聚类分析可将样品分为3类,正交偏最小二乘判别分析筛选出5个质量差异标志性成分。不同采收时间枸橘药材可以通过果皮颜色区分,枸橘苷、柚皮苷、欧前胡素等是导致枸橘药材质量产生差异的主要标志物。结论:果皮颜色可作为枸橘药材的采收依据;枸橘苷、柚皮苷和欧前胡素等是枸橘药材质量差异标志物。

A Study of the Effect of <i>Citrus aurantium</i>L. Essential Oil on Anxiety and Its Interaction with GABAergic Pathways in Male Mice

Anxiety is among the most common disorders affecting a great number of people. Different neurotransmitter systems, such as GABAergic system, play an important role in emergence of anxiety-related behaviors. In this study, we have investigated the effect of Citrus aurantium L. essential oil on anxiety and its interaction with GABAergic pathways. Male mice were assigned into control, sham, and experimental groups. Intraperitoneal injection of Citrus aurantium L. essential oil was applied at doses of 0.5, 2.5, and 5 percent for 5 days. Diazepam (0.1 mg/kg) was injected on the fifth day, thirty minutes before applying Citrus aurantium L. essential oil. The anxiety-related behavior of mice was then assessed using elevated plus-maze test. In groups receiving Citrus aurantium L. essential oil at doses of 2.5 and 5 percent, the percent time spent in the open arms increased significantly (P Citrus aurantium L. essential oil resulted in increasing in the number of entries to the open arms and the percent time spent in the open arms (P Citrus aurantium L. essential oil can reduce anxiety-related behaviors in male mice thah may act via GABAergic system.

Effect of <i>Citrus aurantium</i>L. Essential Oil and Haloperidol on Anxiety in Male Mice

Relationship between sociability and the amount of brain’s dopamine is very well known. In this study, we have examined the effect of Citrus aurantium L. essential oil on anxiety and its interaction with dopaminergic pathways. 70 male mice were assigned into experimental, control, and sham groups. Essential oil of Citrus aurantium L. was injected intraperitonealy at doses of 0.5%, 2.5% and 5% for 5 days. Subcutaneous injection of haloperidol was administered on the fifth day, 30 minutes before the injection of the essential oil. The anxiety-related behavior of mice was then assessed by elevated plus-maze test. The result of this study showed that the injection of Citrus aurantium L. essential oil at doses of 2.5% and 5% increased significantly the time spent in the open arms (OAT) (p < 0.001), also there was a significant increase in the number of entries into the open arms (OAE). Injection of different doses of the essential oil along with haloperidol significantly increased OAT (p < 0.001(. The results demonstrate that the essential oil of Citrus aurantium L. along with haloperidol medication reduces anxiety-related behaviors.

Interaction of Flomazenil with Anxiolytic Effects of <i>Citrus aurantium</i>L. Essential Oil on Male Mice

Due to our previous findings about the role of GABAegic neurotransmission in anxiolytic effects of Citrus aurantium L. essential oil, we are now presenting flomazenil interaction with this herb, as an antagonist of benzodiazepines at GABA receptor. The study was performed on 84 male albino mice assigned to 14 groups of six. The animals were injected intraperitoneally with the Citrus aurantium L. essential oil for 5 days. On the fifth day, either normal saline or flomazenil (0.1 mg/kg) was injected to the experimental groups. Thirty minutes after the injection, all the groups were assessed for anxiety-related behavior by elevated plus-maze test. In groups receiving Citrus aurantium L. essential oil at doses of 2.5 and 5 percent, the time spent in the open arms increased significantly (P aurantium L. essential oil regarding the increment in the number of entries to the open arms and the time spent in the open arms (P aurantium L. essential oil induces its anxiolytic effects like benzodiazepines, in the same site at GABA receptor.

Identification of Genetic Variation in Citrus sinensis from Hunan Based on Start Codon Targeted Polymorphism

[Objective] The aim was to identify genetic variation in Citrus sinensis （sweet orange） germplasm from Hunan Province according to the Start Codon Targeted （SCoT） Polymorphism. [Method] The reaction system for SCoT amplification from sweet orange was first optimized, and then the SCoT fragments were amplified from 24 sweet orange cultivars collected in Hunan Province and sequenced for genetic variation analysis. [Result] The optimum reaction system for SCoT markers amplification was 2.0 μl containing 80 ng of template DNA, 0.3 mmol/L dNTPs, 0.2 μmol/L primer, 1.6 mmol/L Mg2＋, 1.6 U of Taq DNA polymerase and 10×PCR buffer. By using this reaction system, the PCR products from the sweet orange cultivars produced clear and reproducible bands at 100-2 000 bp through electrophoresis. The SCoT fragments of the 24 sweet orange cultivars were 1 090-1 091 bp, with the homology of 99.84% and nucleotide deletion and substitution. After being sequenced, the SCoT polymorphisms could distinguish 12 sweet orange cultivars. In addition, the BLAST result showed that part of the SCoT fragments coding region shared high homology with ribosomal protein S3 N superfamily. [Conclusion] This study will provide a theoretical basis for breeding sweet orange cultivars.

红肉脐橙(Citrus sinensis L.)果肉中特征色素提取方法探索

红肉脐橙是目前为止惟一果肉呈粉红色或红色的脐橙,其呈色色素尚未见报道。为深入研究其果肉中特征色素的构成及在果实生长发育和贮存过程中色素含量的变化,本研究在对该色素初步定性的基础上对提取方法进行了探索。在分析红肉脐橙果肉中色素萃取液的紫外可见吸收光谱时发现,该色素有类胡萝卜素的特征吸收峰,将萃取液进行薄层层析则进一步证实其内含有番茄红素。在色素提取的前处理方式上,本研究认为冷冻干燥样品的浸提效果较真空干燥的样品稳定(变异系数小),且浸提率相差无几,所以选择冷冻干燥作为合适的样品前处理方式。色素浸提条件的正交实验结果表明,最佳浸提条件为50℃、1.5h内浸提4次,浸提的料液比为1:60。此外,浸提温度、浸提时间、浸提料液比和浸提次数对浸提率都有显著影响,影响最大的因素是浸提温度,最佳温度为50℃,随温度降低浸提率显著降低。其次是侵提时间的长短,最佳浸提时间为1.5h,延长或缩短0.5h都会使浸提率下降。浸提次数对浸提率的影响是最小的。

Phenolic and flavonoid contents of mandarin (Citrus reticulata Blanco) fruit tissues and their antioxidant capacity as evaluated by DPPH and ABTS methods

The total phenolic and flavonoid contents in the fruit tissues （peels, pulp residues, seeds, and juices） of 19 citrus genotypes belonged to Citrus reticulata Blanco were evaluated and their antioxidant capacity was tested by 2,2-diphenyl-l-picrylhydra- zyl radicals （DPPH） method and 2,2＇-azino-bis（3-ethylbenzthiozoline-6）-sulphonic acid （ABTS） method. The total phenolic and flavonoid contents, and their antioxidant capacity varied in different citrus fruit tissues. Generally, the peel had both the highest average of total phenolics （27.18 mg gallic acid equivalent （GAE） g^-1 DW） and total flavonoids （38.97 mg rutin equivalent （RE） g^-1 DW）. The highest antioxidant capacity was also the average of DPPH value （21.92 mg vitamin C equiv- alent antioxidant capacity （VCEAC） g^-1 DW） and average of ABTS value （78.70 mg VCEAC g-1 DW） in peel. The correlation coefficient between the total phenolics and their antioxidant capacity of different citrus fruits tissues ranged from 0.079 to 0.792, and from -0.150 to 0.664 for the total flavonoids. The antioxidant capacity of fruit tissues were correlated with the total phenoilc content and flavonoid content except in case of the peel. In addition, the total phenolic content and antioxidant capacity varied in different citrus genotypes. Manju and Karamandarin were better genotypes with higher antioxidation and the phenolic content, however Shagan was the poorest genotype with lower antioxidation and the phenolic content.

HPLC测定枳实导滞丸中枳实所含6种成分及其药材基原分析

目的建立枳实导滞丸中芸香柚皮苷、柚皮苷、橙皮苷、新橙皮苷、水合橙皮内酯、马尔敏的含量测定方法,同时鉴别其中枳实来源。方法采用Waters Symmetry C 18柱(250 mm×4.6 mm,5μm)色谱柱分析,以乙腈(A)-乙酸水(B)为流动相,梯度洗脱,柱温30℃,流速:1.0 mL·min^(-1),检测波长:285 nm、320 nm,进样量10μL。结果6个成分在各自线性范围内均符合要求,相关系数r均≥0.9993;各成分平均回收率范围在98.68%~101.16%,RSD均≤2.5%。12批枳实导滞丸中芸香柚皮苷质量分数在0.37~5.65 mg·g^(-1),柚皮苷在0~12.16 mg·g^(-1),橙皮苷在0~53.90 mg·g^(-1),新橙皮苷在0~18.90 mg·g^(-1),水合橙皮内酯在0~0.23 mg·g^(-1),马尔敏在0~0.13 mg·g^(-1)。12批次枳实导滞丸样品分别呈现与酸橙或甜橙药材一致的黄酮类成分含量情况。香豆素类成分主要存在于酸橙制备的丸剂中且含量偏低。结论该方法简便、准确、可靠,可同时测定枳实导滞丸中6种有效成分的含量并鉴别丸剂中枳实的基原,可为枳实导滞丸质量评价提供依据。

Integrated multi-omics analysis of developing‘Newhall’orange and its glossy mutant provide insights into citrus fragrance formation

Sesquiterpene valencene is dominant in flavedo tissues of sweet oranges and imparts a unique woody aroma.However,the interaction between the biosynthetic pathways of valencene and other nutritional compounds is less studied.Sesquiterpenoids were significantly accumulated in a previously reported glossy mutant of orange(MT)than the wild type(WT),especially valencene and caryophyllene.In addition,we identified several other pathways with variations at both the transcriptional and metabolic levels in MT.It’s interesting to found those upregulated metabolites in MT,such as eukaryotic lipids,kaempferol and proline also showed strong positive correlation with valencene along with fruit maturation while those down-regulated metabolites,such as phenylpropanoid coumarins and most of the modified flavonoids exhibited negative correlation.We then categorized these shifted pathways into the‘sesquitepenoid-identical shunt’and the sesquitepenoid-opposite shunt’and confirmed the classification result at transcriptional level.Our results provide important insights into the connections between various fruit quality-related properties.

<i>In-Vitro</i>Regeneration of <i>Citrus sinensis</i>(L.) Osbeck from Mature Seed Derived Embryogenic Callus on Different Solid Basal Media

In-vitro callus induction and regeneration method was developed using different plant growth regulators (PGRs), and basal media (Murashige and Skoog (MS), CHU (N6) and Gamborg (B5) media) of Citrus sinensis (L.) Osbeck. Observations of the effect of PGRs were carried out using different concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D),1-naphthalene acetic acid (NAA) and combinations of 2,4-D and NAA using different basal media. This study found Citrus sinensis (L.) Osbeck exhibited a high frequency of callus induction on MS medium supplemented with 3 mg/L 2,4-D and callus induction frequency was 86.7% ± 3.4% whereas N6 and B5 showed lower callus induction frequency of 83.3% ± 8.8% and 82.2% ± 1.9% respectively compared to that of MS media with supplementation of the same hormone. Among the induced calli, the morphological analysis showed only 40% - 50% was embryogenic calli. Regeneration of plantlets from calli was done using different concentrations and combinations of auxin and cytokinin. The study showed that 3 mg/L 6-benzylaminopurine (BAP) supplemented medium has the maximum potential to promote regeneration of Citrus sinensis (L.) Osbeck from embryogenic calli with the frequency of 89.3% ± 8.8% but no regeneration occurred from the non-embryogenic calli. The regenerated plantlets were rooted on MS medium with supplementation of 5 mg/l NAA. These observations in Citrus sinensis (L.) Osbeck regeneration will be helpful for genetic improvement with desired traits.

Study on Infrared Spectra of Citrus grandis Peels from Guangxi Zhuang Autonomous Region

[ Objective ] This study aimed to establish the infrared （IR） spectra fingerprints for peels of Citrus grandis from Guangxi Zhuang Autonomous Region. [ Method ] The fingerprint was established by fourier transform infrared spectroscopy （ FT-IR）, and then were analyzed by Omic software. [ Result ] IR spectra fin- gerprint of C. grand/s were successfully established. There were six common peaks in the characteristic spectra of 12 samples. [ Conclusion] The specific, rapid and stable method can be applied to quality control of C. grandis.

Religious and Cultural Significance of the Citron （Citrus medica L. ＇Diamante＇） from Calabria （South Italy）： A Biblical Fruit of the Mediterranean Land

The history and geographical origin of citron （Citrus medica L.） is still unknown but most of authors agree that it originated in Southeast Asia. There are different opinions about the exact period and the steps by which it was brought from its country of origin to the Mediterranean basin where it is cultivated in Corsica, Crete and in southern Italy （Calabria region）. In particulary, Citrus medica ＇Diamante＇ grows, almost exclusively, in a restricted area of the Tyrrhenian cost of the region Calabria, called ＂Riviera dei Cedri＂, a relevant local economic district. This citron has been and is, still being used by Jews for worship during the Feast of Tabernacles, a very important religious ritual, where it plays a prominent part; in fact, for this holiday of Sukkot, the use of the authentic citron that grows in Calabria region is recommended, because it is not grafted. In this paper, the fascinating history of C. medica and its spread from the centers of origin to the Mediterranean is reported with the aim to investigate the religious and cultural significance of the C. medica ＇Diamante＇, an exclusive and historical heritage of the Calabria region.

不同采收期的酸橙叶片形态及药材质量比较

研究不同采收期酸橙(Citrus aurantium L.)药材干燥后枳实和枳壳的性状特点,比较水分、灰分、浸出物含量和主要化学成分的变化规律,确定酸橙药材枳实和枳壳的最佳采收期,并为充分利用酸橙资源、完善质量控制提供科学依据。采用甲苯法测定水分、热浸法测定浸出物含量,按《中华人民共和国药典(2020年版四部)》规定的方法测定灰分,采用高效液相色谱法测定枳实、枳壳中辛弗林和3种黄酮苷的含量。结果表明,酸橙中果、大果性状稳定性较优,与药典规定规格相近。随着采收期推后,酸橙药材柚皮苷含量呈先升高后降低的趋势,新橙皮苷、橙皮苷、辛弗林含量均呈下降趋势。综合考虑劳动力、时间成本、药材性状、药材有效化学成分等,确定中果酸橙的枳实质量为佳,枳实6月中旬采摘为佳,枳壳7月上中旬果皮尚绿时采收为佳。

马家柚叶绿体基因组特征及其密码子偏好性分析

【目的】为了明确马家柚叶绿体基因组结构特征及其与同属类群的系统发育关系,阐明马家柚在柑橘属中的分类地位,对马家柚叶绿体基因组的特征及其密码子的偏好性进行分析。【方法】采用DNBSEQ-T7测序平台对马家柚进行测序,采用Noveplastys、CAP3、GeSeq和tRNAscan-SE软件对马家柚叶绿体基因组进行组装、注释;采用CGViewServer、MISA、REPuter、CodonW、Gview、IRscope、NADnaSP6.0软件对马家柚叶绿体基因组特征进行分析;采用MAFFT 7.0和FastTree 2.1.10软件对马家柚及其85个同科种和山小橘属3个外群种叶绿体基因组进行序列比对和建树。【结果】马家柚叶绿体基因组全长160186 bp,包括1个大单拷贝(LSC)区、1个小单拷贝(SSC)区和2个反向重复(IR)区,为典型闭合环状双链结构。马家柚叶绿体基因组共注释到133个功能基因,包括88个编码蛋白(CDS)基因、8个核糖体RNA(rRNA)基因和37个转运RNA(tRNA)基因。马家柚叶绿体基因组共检测到79个简单序列重复(SSR)和34个长序列重复(Longrepeat)。马家柚叶绿体基因组非编码区的变异程度高于基因编码区,LSC区的变异性>SSC区>IR区,SC/IR边界较为保守。马家柚叶绿体基因组平均ENC值为48.02,密码子偏好性较弱。马家柚叶绿体基因组密码子使用偏好性主要受自然选择的影响,受内部突变的影响小。马家柚叶绿体基因有10个最优密码子(AAU、UGU、AAA、UUU、GCU、GGA、CCA、ACU、CGU、AGU),均以A、U结尾。马家柚与西双版纳东试早柚(KY055833,来源地:云南)、日本夏橙(ON193075,来源地:韩国)、福建六月早蜜柚(MT527726,来源地:福建)、福建琯溪蜜柚(MN782007,来源地:福建)有亲缘关系。【结论】马家柚是一个柑橘属中较为独特的品种,该研究结果为进一步研究马家柚的遗传资源、物种资源鉴定和系统发育分析提供了理论依据。

酸橙夏季光合作用特性研究

[目的]研究酸橙夏季光合作用特性。[方法]采用Li-6400便携式光合作用测定系统测定酸橙不同位置叶片净光合速率、酸橙光合日变化、光响应曲线和CO_(2)响应曲线。[结果]酸橙不同方位和不同部位叶片净光合速率存在一定差异;酸橙夏季净光合速率日变化呈双峰型,存在“午睡”现象,其光合峰值分别出现在10:00和14:30;气孔导度的日变化与净光合速率日变化相似。从光响应曲线看,酸橙光饱和点高,光强为0~2000μmol/(m^(2)·s),净光合速率不断上升,最大为13.44μmol/(m^(2)·s),光补偿点为28.33μmol/(m^(2)·s),表观光量子效率为0.036。从CO_(2)响应曲线看,酸橙CO_(2)饱和点在1500μmol/mol,CO_(2)补偿点为60.65μmol/mol,羧化效率为0.079。相关及回归分析结果表明,夏季酸橙净光合速率与气孔导度、空气相对湿度、胞间CO_(2)浓度、蒸腾速率、水汽压亏缺等生理生态因子关系密切。[结论]酸橙是一种喜阳的C_(3)型植物,且对弱光有较强的适应及利用能力,对CO_(2)具有较强的同化能力,同时在夏季高温低湿环境下,酸橙光合作用受各种生理生态因子影响,此期光合有效辐射不是影响净光合速率的关键因子,空气相对湿度与净光合速率呈显著正相关,因此通过环境选择或增加相对湿度的措施,可缓解酸橙夏季“午睡”现象,提高净光合效率。