Two previously undescribed oleanane-type triterpenoids, 16α,22α,23,28-tetrahydroxyolean-12-en-3-one (1) and 4α-methyl-16α,21β,22α, 27-tetrahydroxyolean-12-en-3-one (2), together with three known analogues (3–5), were isolated from the seed cake of Camellia oleifera Abel. Their molecular structures were determined by NMR, HRMS and X-ray crystallography. Compound 2 features a rare C-4 monomethyl substitution. The anti-inflammatory activity of all compounds was evaluated in LPS-induced RAW264.7 macrophages. They dose-dependently inhibited the production of IL-6, NO, PGE2, and TNF-α without obvious cytotoxicity. Compound 4 exhibited the most potent broad-spectrum inhibition, while compounds 2 and 3 showed selective suppression of IL-6 and TNF-α, respectively. These findings expand the chemical diversity of triterpenoids from C. oleifera seed cake and highlight its potential as a source of anti-inflammatory lead compounds. The rare C-4 methylated skeleton of compound 2 provides new insights into structure–activity relationships among oleanane-type triterpenoids.

Soil organic carbon (SOC) loss in sloping farmland is a critical challenge for agricultural sustainability. This study investigated how citrus peel biochar (CPB), field snail shell powder (SSP), and their composite (CPB + SSP) differentially regulate SOC dynamics across slope positions (upper, middle, lower) in Guangxi’s citrus orchards. Key findings revealed: CPB significantly increased SOC content (up to 5.5 g·kg−1 at lower slopes) via high carbon input but suppressed mineralization amount in lower slope position (reduction of 17.9%) due to its high C/N ratio. SSP neutralized soil acidity (pH 3.95 to 7.5), stimulating microbial activity and raising mineralization rates by 58.95% (lower slope), yet minimally enhanced SOC (only +0.7 g·kg−1). CPB + SSP effectively balanced carbon stability and active release: dissolved organic carbon (DOC) and readily oxidizable organic carbon (ROC) increased by 14.4 mg·kg−1 and 0.22 g·kg−1 (middle slope), while SOC rose significantly (e.g., +2.2 g·kg−1 at lower slope). Slope position effects strongly influenced outcomes: the lower slope (highest initial SOC) responded most strongly to CPB for carbon stabilization, while middle slopes benefited from CPB + SSP to reconcile carbon loss with fertility. These results provide slope-specific strategies for SOC management by integrating amendment synergy and machine learning-driven insights in citrus orchards.

Forests play an important role in promoting carbon cycling and mitigating the urban heat island effect as one of the world’s major carbon storages. Scientifically quantifying tree biomass is the basis for assessing tree carbon storage and other ecosystem functions. In this study, a sample plot of Populus tomentosa plantation in the Olympic Forest Park in Beijing was selected as the research object. Point cloud data from three types of laser scanners, including terrestrial laser scanner (TLS), backpack laser scanner (BLS), and handheld laser scanner (HLS), were used to estimate the biomass of single tree trunks, branches, leaves, and aboveground total biomass based on the Allometric Biomass Model (ABM) and Advanced Quantitative Structure Model (AdQSM). The following conclusions were drawn from the estimation results: (1) For the three types of laser scanner point clouds, the biomass estimation values obtained using the AdQSM model were generally higher than those obtained using the Allometric Biomass Model. However, the estimation values obtained using the two models were similar, especially for tree trunks and total biomass. (2) For total biomass and individual biomass components of single trees, the results obtained from handheld and terrestrial laser scanner point clouds are consistent; however, they show some differences from the results obtained from backpack-mounted point clouds. This study further enriches the methodological system for estimating forest biomass, providing a theoretical basis and reference for more accurate estimates of forest biomass and more sustainable forest management.

通过对奈李进行套袋技术试验,研究套袋对奈李果实外观及品质的影响.结果表明:套袋能明显改善奈李的外观品质,提高商品果率.套袋处理提升了奈李果实蔗糖和山梨醇的含量,但果糖和Vc含量显著降低,套袋奈李果实的糖酸比及固酸比高于未套袋果实.

为探明"无核沃柑"的无核成因,以"沃柑""无核沃柑"为试验材料,对其花药发育、异交亲和性和种子发育进行了观察研究.结果表明,"沃柑""无核沃柑"花药发育均不良,表现为花粉囊狭小甚至缺失,产生的花粉粒少,同属于败育型花药."沃柑""无核沃柑"采用"桂橙1号""琯溪蜜柚""北京柠檬"花粉异花授粉后,花粉管均能正常生长进入子房室."沃柑""无核沃柑"的种子数差异大,不同授粉组合的"沃柑"平均每果种子数为10～18.5粒,"无核沃柑"平均每果种子数为0～1.5粒."沃柑""无核沃柑"的种子发育动态不同."沃柑"异花("琯溪蜜柚"花粉)授粉后4周胚珠出现明显的大小分化,授粉后12～16周合子胚从球形、心形快速发育成子叶胚,授粉后20周部分子叶胚已占满整个胚囊."无核沃柑"异花("琯溪蜜柚")授粉后2周胚珠已停止发育,部分珠心细胞解体,授粉后10周胚珠组织细胞明显解体、萎蔫,授粉后12周完全萎蔫、皱缩,形成0.5 mm左右的微小瘪子.雌性不育、受精受阻或胚早期败育均可能是"无核沃柑"无核的成因.

柳叶菜花是桂林地方特色菜心品种,富含多种维生素及微量元素.为了探究自然温度下柳叶菜花品质变化规律,试验通过采收不同自然温度条件下的柳叶菜花,测定其可溶性固形物、粗纤维、粗蛋白、还原糖以及Vc等生理指标,结合温度分段统计的方法,分析温度变化与柳叶菜花品质变化的相关性以及变化规律.试验结果表明,柳叶菜花品质形成的最佳温度条件为在自然温度条件下,当低于5℃的累积时长达到14h左右且低于10℃的累积时长约占采收前10d总时长的50％时,柳叶菜花的营养品质基本达到了最高水平.研究分析了柳叶菜花不同温度条件下主要营养指标的变化规律,为获得高品质菜花气候条件的选择提供理论依据.

Polyploids have elevated stress tolerance, but the underlying mechanisms remain largely elusive. In this study, we showed that naturally occurring tetraploid plants of trifoliate orange (Poncirus trifoliata (L.) Raf.) exhibited enhanced cold tolerance relative to their diploid progenitors. Transcriptome analysis revealed that whole-genome duplication was associated with higher expression levels of a range of well-characterized cold stress-responsive genes. Global DNA methylation profiling demonstrated that the tetraploids underwent more extensive DNA demethylation in comparison with the diploids under cold stress. CHH methylation in the promoters was associated with up-regulation of related genes, whereas CG, CHG, and CHH methylation in the 3'-regions was relevant to gene down-regulation. Of note, genes involved in unsaturated fatty acids (UFAs) and jasmonate (JA) biosynthesis in the tetraploids displayed different CHH methylation in the gene flanking regions and were prominently up-regulated, consistent with greater accumulation of UFAs and JA when exposed to the cold stress. Collectively, our findings explored the difference in cold stress response between diploids and tetraploids at both transcriptional and epigenetic levels, and gained new insight into the molecular mechanisms underlying enhanced cold tolerance of the tetraploid. These results contribute to uncovering a novel regulatory role of DNA methylation in better cold tolerance of polyploids.

为探讨树冠覆膜对沙糖橘树冠环境、光合作用和果实品质的影响,以沙糖橘为试验材料,树冠覆膜为处理、不覆膜为对照,分别记录树冠的温度、湿度和光照强度等环境因子指标,测定叶片的净光合速率、气孔导度、蒸腾速率和胞间二氧化碳浓度等光合作用指标,分析果实的可溶性固形物、总糖、可滴定酸及维生素C等品质指标.与对照相比,树冠覆膜后,总体上沙糖橘树冠白天的光照强度和湿度降低,降幅分别为36.36％～63.64％和5.25％～7.56％,月均温度和月均昼夜温差增加,最大分别增加1.21℃和3.88℃,净光合速率下降,最大降幅45.95％;果实的可溶性固形物、总糖及糖酸比等果实品质指标显著提高,分别增加7.81％、23.46％和4.87％.树冠覆膜在延长沙糖橘采收期的同时,总体上保持了较好的果实品质.

植物组织结构与细胞形态学观察是植物系统分类、遗传演化、抗逆反应等的主要研究方法之一.本文研究了不同材料处理和不同切片方法对柑桔叶脉组织细胞荧光显微观察的影响.结果表明,利用荧光显微技术可以简便、有效地观测柑桔叶脉的组织结构和细胞形态,新鲜材料徒手切片和冷冻切片、FAA固定材料冷冻切片在荧光显微镜下都可以得到较佳的观测效果;几种处理方法各有优缺点,研究中可以根据具体情况灵活选用.

以2年生盆栽南丰蜜橘为试验材料,以未感染黄龙病的健康树作为对照,分析了感染黄龙病的病树叶片中脱落酸(ABA)、赤霉素(GA3)、吲哚乙酸(IAA)和玉米素核苷(ZR)的含量变化规律.结果表明,与对照相比,南丰蜜橘被黄龙病侵染后5～10天叶片中ABA含量显著降低,GA3、IAA和ZR含量显著提高,可把激素含量变化作为黄龙病早期检测的一个辅助手段.

对野生柑橘种质资源和疑似耐(抗)柑橘黄龙病种质材料进行了收集,共收集了177份材料,其中野生柑橘资源19份,田间疑似耐(抗)柑橘黄龙病种质材料158份,包括'砂糖橘'25份、'沙田柚'29份、椪柑65份、橙类19份、'桂橘一号'5份、温州蜜柑10份、'蜜广橘'2份、'南丰蜜橘'1份及其他柑橘材料2份.对收集的疑似耐(抗)病材料进行嫁接和保存,并建立耐(抗)柑橘黄龙病柑橘种质材料保存圃1个.通过高接染毒法对疑似耐(抗)黄龙病柑橘种质材料进行鉴定,通过田间症状观察诊断和定性/定量PCR检测,初步筛选出16份对黄龙病有耐性的种质材料,包括4份野生柑橘材料和12份田间耐病材料,为柑橘的抗病育种奠定了基础.

为了解桂林市沙糖桔产区叶片营养元素的丰缺状况,进而为合理施肥提供参考,于2017年9-10月调查分析了6个县60个果园叶片的氮(N)、磷(P)、钾(K)、钙(Ca)、镁(Mg)、硼(B)、铁(Fe)、锰(Mn)、铜(Cu)、锌(Zn)含量,并根据柑桔叶片营养相关分级标准判定丰缺状况.结果 表明,桂林市沙糖桔叶片N和B普遍丰富,含量偏多(超过适量水平,包括高量和过量水平)果园的比例分别为43.33％和78.33％;叶片P、K、Ca、Mg、Cu和Zn偏少的现象较明显,含量不足(低于适量水平,包括低量和缺乏水平)果园比例分别为38.33％、35.00％、40.00％、43.33％、65.00％和81.67％;叶片Fe和Mn适量的果园比例分别为65.00％和66.67％,均同时存在偏多或不足的现象.桂林市沙糖桔产区树体营养元素失衡现象普遍存在,总体上,生产中应减少N和B肥的用量,改善P、K肥施肥方式提高其利用效率,重视叶面施肥补充Ca、Mg、Cu、Zn,合理施用Fe和Mn肥,以确保树体营养均衡.

树冠覆膜技术已在金柑生产中得到广泛应用.该研究以阳朔金柑为材料,树冠覆膜作为处理,不覆膜作为对照,分别测定处理和对照的树冠的温度、湿度和光照强度等环境因子的变化,观测处理和对照的叶面积、叶长、叶宽及叶绿素含量,测定处理和对照的净光合速率、气孔导度、蒸腾速率和胞间二氧化碳浓度等光合作用指标,并分析处理和对照的果实硬度、可溶性固形物、总糖、可滴定酸及维生素C含量等果实品质指标.结果表明:与对照相比,金柑树冠覆膜处理后,树冠的光照强度降低、温度上升、湿度下降、叶面积增大、叶绿素含量提高,净光合速率下降且最大降幅是对照的21.39％,果实的可滴定酸降低,但硬度、可溶性固形物、总糖、固酸比及糖酸比等果实品质指标提高.金柑树冠覆膜处理减少了树冠的光照,降低了净光合速率,但增加了叶面积和叶绿素含量,从而保障了光合同化物的累积,提高了果实的可溶性固形物和总糖.同时,树冠覆膜处理还提高了树冠白天的气温,降低了可滴定酸,增大了固酸比和糖酸比,因此从总体上提高了果实品质.

以广西荔浦市的沙糖橘为试材,研究了果实大小[2S(3.5～4.0 cm)、S(4.0～4.5 cm)、M(4.5～5.0 cm)和L(5.0～5.5 cm)]、贮藏期(0～45 d,12月26日至翌年2月13日)对沙糖橘果实浮皮和果肉糖酸含量变化的影响.结果表明:采收期和贮藏期,果实大小与浮皮程度正相关,与可滴定酸含量负相关,即果实越大,浮皮程度越重,可滴定酸含量越低;果实大小与可溶性固形物含量的相关性不明显.随贮藏时间的延长,各等级果实的浮皮率和浮皮指数先升后降,可溶性固形物含量先升高后平稳保持,可滴定酸含量持续下降.结论:不同大小的沙糖橘果实贮藏期均能保持较好的糖酸风味,但大果在采收期和贮藏期浮皮程度较重.为避免浮皮引起的损伤,建议先行销售大果.中小果在采收期和贮藏期浮皮程度较轻,可适当延长贮藏时间.

Green mold caused by Penicillium digitatum is a serious postharvest disease of citrus. In this study, we obtained a new strain with potent biocontrol activity to control green mold of citrus, and it was characterized as Bacillus sp. w176 by physiological, biochemical, and 16S rDNA analyses. Cell-free supernatant (CFS) of strain w176 in PDB culture was analyzed by Liquid Chromatography Tandem Mass Spectrometry (LCMS/MS). There were more than four different groups of possible metabolites including macrolactin, bacillaene, mycosubtilin, and surfactin. Additionally, both Bacillus sp. w176 and its CFS could effectively reduce disease incidence and lesion diameter of green mold of citrus in vivo. Bacillus sp. w176 and its CFS reduced green mold by round percentage of 89.3% and 54.46%, respectively. Moreover, both Bacillus sp. w176 and its CFS could similarly inhibit the expansion of green mold on citrus with similar effect compared to the fungicide prochloraz after three months of storage. Transmission Electron Microscope (TEM) examination showed that subcellular structure of P. digitatum was changed involving vacuolation, when it was incubated with CFS. Gene expression analysis indicated a change in redox and ribosome biogenesis stress-related genes transcript levels, when P. digitatum were treated with CFS. These results suggested that both Bacillus sp. w176 and its CFS might be valuable for disease control purpose. Our study may provide a novel biological agent to control the citrus green mold and improve our understanding of the possible biocontrol mechanisms of strain w176.

在广西荔浦市,以树冠覆膜留树保鲜的沙糖桔为试材,研究了果实大小(按横径分级:2S级,3.5～4.0 cm;S级,4.0～4.5 cm;M级,4.5～5.0 cm;L级,5.0～5.5 cm;2L级,5.5～6.0 cm)和留树保鲜时间(12月12日至翌年2月28日)对果实浮皮和果肉品质的影响.结果 表明,果实大小和留树保鲜时间对浮皮程度均有显著影响,果实越大、留树保鲜时间越长,浮皮率越高、浮皮指数越大.在留树保鲜前期(1月底以前),各级果实的可溶性固形物含量和可滴定酸含量差异规律性不明显;后期,可溶性固形物和可滴定酸含量表现为随果实增大而降低.随留树保鲜时间的延长,25、S、M级果实的可溶性固形物含量呈小幅上升趋势,L和2L级果实的可溶性固形物含量呈波动变化、规律性不明显;各级果实的可滴定酸含量均呈先降后升、总体下降的变化趋势,1月底最低;各级果实的固酸比表现为先升后降、总体上升的变化趋势,1月底最大.

Summary Tetraploids have been reported to exhibit increased stress tolerance, but the underlying molecular and physiological mechanisms remain poorly understood. In this study, autotetraploid plants were identified by screening natural seedlings of trifoliate orange (Poncirus trifoliata). The tetraploids exhibited different morphology and displayed significantly enhanced drought and dehydration tolerance in comparison with the diploid progenitor. Transcriptome analysis indicated that a number of stress‐responsive genes and pathways were differentially influenced and enriched in the tetraploids, in particular those coding for enzymes related to antioxidant process and sugar metabolism. Transcript levels and activities of antioxidant enzymes (peroxidase and superoxide dismutase) and sucrose‐hydrolysing enzyme (vacuolar invertase) were increased in the tetraploids upon exposure to the drought, concomitant with greater levels of glucose but lower level of reactive oxygen species (ROS). These data indicate that the tetraploids might undergo extensive transcriptome reprogramming of genes involved in ROS scavenging and sugar metabolism, which contributes, synergistically or independently, to the enhanced stress tolerance of the tetraploid. Our results reveal that the tetraploids take priority over the diploid for stress tolerance by maintaining a more robust system of ROS detoxification and osmotic adjustment via elevating antioxidant capacity and sugar accumulation in comparison with the diploid counterpart.

Huanglongbing (HLB) is one of the most destructive diseases in citrus production worldwide. Early detection of HLB pathogens can facilitate timely removal of infected citrus trees in the field. However, low titer and uneven distribution of HLB pathogens in host plants make reliable detection challenging. Therefore, the development of effective detection methods with high sensitivity is imperative. This study reports the development of a novel method, tandem repeat-based polymerase chain displacement reaction (TR-PCDR), for the detection of ‘Candidatus Liberibacter asiaticus’, a widely distributed HLB-associated bacterium. A uniquely designed primer set (TR2-PCDR-F/TR2-PCDR-1R) and a thermostable Taq DNA polymerase mutant with strand displacement activity were used for TR-PCDR amplification. Performed in a regular thermal cycler, TR-PCDR could produce more than two amplicons after each amplification cycle. Sensitivity of the developed TR-PCDR was 10 copies of target DNA fragment. The sensitive level was proven to be 100× higher than conventional PCR and similar to real-time PCR. Data from the detection of ‘Ca. L. asiaticus’ with filed samples using the above three methods also showed similar results. No false-positive TR-PCDR amplification was observed from healthy citrus samples and water controls. These results thereby illustrated that the developed TR-PCDR method can be applied to the reliable, highly sensitive, and cost-effective detection of ‘Ca. L. asiaticus’.

Clemenules、Hernadina、Spinoso V.C.R、SRA63、Marisol、Pons等6个克里曼丁红橘新品种系广西特色作物研究院2015年从湖南农业大学引入,在2016～2017年进行了物候期观察、果实品质分析等生物学性状观察.结果表明:克里曼丁红橘新品种在广西表现丰产、品质好、化渣、有特殊香味;并筛选出SRA63、Pons和Hernadina 3个综合性状表现优良、适合在广西推广种植的优良品种.

[目的]溃疡病是严重危害柑橘的一种细菌性病害,通常在高温下容易发生.论文旨在阐明高温下柑橘易发生溃疡病的机制,揭示其代谢变化,为利用药剂防治溃疡病提供重要的理论指导.[方法]以感病的甜橙(Citrus sinensis)为研究对象,在21℃和30℃下预培养3d,然后均接种同样浓度(108cfu/mL)的柑橘溃疡病菌(Xanthomonas citri subsp.citri,Xcc)10 μL,比较两组植株的发病率,采用半定量RT-PCR分析两种温度下4个抗病基因AOS、CHI、GPX和PR4A的表达量,利用HPLC测定预培养3d后叶片内源多胺(腐胺、亚精胺和精胺)的含量.在此基础上,利用外源亚精胺(0.4 mmol·L-1)处理甜橙植株(以清水处理为对照),比较亚精胺和清水处理的植株接种溃疡病菌后的发病率和病情指数,分析亚精胺处理对内源多胺含量和抗病基因AOS、CHI、GPX和PR4A表达的影响.[结果]溃疡病菌接种后观察发现,21℃培养植株溃疡病的发病率在前期低于30℃培养的植株,至第10天时,两个处理组植株的发病率接近;同时HPLC测定发现,21℃培养植株叶片3种自由态多胺(腐胺、亚精胺和精胺)含量高于30℃培养植株;RT-PCR分析表明,CHI、GPX和PR4A这3个抗病基因的表达量在21℃培养植株中高于30℃培养植株,而AOS表达水平在两组材料中差异不明显.外源亚精胺处理显著增加了内源腐胺和亚精胺的含量,降低了所处理植株接种溃疡病菌后的发病率和病情指数,接种后14 d发病率比对照降低45％,病情指数比对照降低4.8,而由表型可见对照发病程度重于亚精胺处理材料.此外,亚精胺处理能够增强AOS、CHI、GPX和PR4A4个抗病基因的表达量.[结论]高温下甜橙更易发生溃疡病的可能机制是高温抑制抗病基因的表达和多胺合成.外源多胺处理能够降低甜橙发生溃疡病,可能机制是多胺处理后增强了抗病基因的表达,诱发植株的抗病反应最终表现出抗病.因此,高温是影响溃疡病发生的一个关键环境因子,多胺有助于提高对柑橘溃疡病的抗性.