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1.
茶枝柑（Citrus reticulata cv. chachiensis）在广东新会地区有悠久的栽培历史,其果皮可制作陈皮,具有一定的药用价值。茶枝柑黄龙病（Citrus Huanglongbing, HLB）发生历史悠久,危害严重,而目前尚无对感染黄龙病的茶枝柑症状描述及病菌Candidatus Liberibacter asiaticus(CLas)分布的相关研究。本研究通过采集广东新会感染CLas茶枝柑枝条和果实,对感病的茶枝柑叶片及果实的典型症状进行观察,同时通过实时荧光定量PCR(real-timequantitative PCR,qPCR)分析CLas在茶枝柑枝条不同部位及果实橘络中的分布规律,为筛选高浓度CLas材料提供依据。观察发现感染CLas的茶枝柑叶片呈现斑驳黄化症状,新叶尤为严重;感染CLas的茶枝柑果实表现出典型的“红鼻子”果症状,果实畸形形状不对称,种子败育。病原定量分析表明,CLas在同一染病茶枝柑枝条中呈不均匀分布：果实中轴组织中的CLas含量最高,为(2 770 162.87±544 972.11)个,其次为橘络(2 721 335.84±528 77... 相似文献
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就实时荧光定量PCR的原理、应用和不足及前景等方面进行了论述。实时荧光定量PCR技术以其快速、灵敏、准确和高通量等特点受到了人们越来越多的重视,被广泛的应用于生物学研究的各个领域。近年来在植物病原检测方面,已建立了一大批植物病原的实时荧光定量PCR方法,这为植物病害的准确诊断与防控提供了强有力的工具。 相似文献
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《大豆科学》2020,(2)
转基因大豆MON87701是由孟山都公司研发的商业化抗虫大豆品系,目前已在17个国家广泛应用。为建立适用于MON87701大豆的高效检测方法,本研究基于实时荧光定量PCR(real-time fluorescence quantitive PCR, qPCR)和芯片式数字PCR(3D digital PCR, 3D-dPCR)平台,对44种不同转基因材料进行测试,建立双重定量检测方法。研究结果显示:只在转基因大豆MON87701样品中获得了阳性结果,证实该方法中引物和探针组合具有较高的特异性。进一步对2%、0.9%、0.09%和0.02%不同含量的MON87701转基因大豆进行定量测试,建立的qPCR和3D-dPCR两种方法的定量限均达到0.09%,检出限均达到0.02%,两者并无明显差别,但由于3D-dPCR和qPCR相比不需要标准物质制作标准曲线,并且对DNA提取质量要求更低,因此使用起来更加便捷高效,为转基因检测提供了新的方法和思路。 相似文献
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以威廉斯8818香蕉为试材,采用整株挖掘、分解取样的方法,研究其干物质的构成特点、各器官矿质元素含量和累积及分布特征。结果表明,香蕉植株果实膨大期总干物质量为5.4 kg/株,其中叶片占36.1%,假茎占34.3%,球茎占15.1%,果实占10.6%,根占2.9%,果轴占1.1%。每株累积吸收N 61.65 g、P 4.40 g、K 49.65 g,N、P、K的吸收比例为1∶0.07∶0.81。此时期,N、P、K分配率规律为叶片＞假茎＞果实,果轴中则最低。叶片中N含量最高,其次为果实和果轴,假茎(叶鞘)最低。P以果实含量最高,叶片次之,球茎最低。K以果实含量最高,根次之,假茎(叶鞘)和球茎最低。叶片、假茎(叶鞘)、真茎(地上茎)和球茎中各矿质元素含量的大小顺序为N＞K＞P,而果实、果轴和根中则为K＞N＞P。 相似文献
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水稻低丰度表达基因OsAMT1;3实时荧光定量PCR方法的建立及其应用 总被引：12，自引：2，他引：10
采用实时荧光定量PCR技术,通过使用特异引物,对水稻中的低丰度表达基因OsAMT1;3进行了转录水平上的定量分析,成功建立了可检测低丰度表达基因的SYBR Green实时荧光定量PCR技术平台。该方法具有很好的准确性和实用性。获得的荧光定量PCR扩增曲线,基线平整,指数区明显,斜率大且固定;线性范围广,17～36个循环都能测出;稳定性、重复性好,变异系数仅为0.47%;标准曲线表明,循环阈值与PCR体系中起始模板量的对数值之间有着良好的线性关系,可对基因表达进行相对定量;缺氮条件下OsAMT1;3 与纯NH4+处理相比表达量增加4倍以上。 相似文献
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华南农业大学根系生物学研究中心采用拟南芥的紫色酸性磷酸酶基因AtPAP15转化大豆品系粤春03－3（YC03-3）,获得了酸性磷酸酶活性明显提高、可高效利用土壤磷素的转基因大豆新品系AP15-1。以AP15-1为研究对象,应用TAIL－PCR技术,根据载体序列设计特异引物,获得了转化载体左侧插入的旁邻序列。设计事件特异性检测引物,进行PCR扩增,只能在AP15-1的样品中扩增出特异性条带,进一步用实时荧光定量PCR作分析,结果显示,该引物对重复性好,融解曲线显示只有一个特异峰值。本实验应用该引物对建立的检测方法,检测的灵敏度可以达到0.01%,实时荧光定量PCR检测的极限值可以达到9个基因组的拷贝数,能够满足对转基因大豆新品系AP15-1及其衍生品种检测的需要。 相似文献
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以柑橘溃疡病菌特异性高的假定蛋白基因（登录号：AE008923.1）为靶标，设计并筛选4条引物来特异性识别靶标序列中的6个独立区域，建立柑橘溃疡病菌LAMP实时浊度检测方法。该方法利用实时浊度仪检测反应过程中产生的焦磷酸镁白色沉淀，实现对LAMP整个反应过程的实时监控。从镁离子浓度、甜菜碱浓度、dNTPs浓度、引物浓度和反应温度5个变量参数对 LAMP检测体系进行优化，并对方法的特异性、灵敏度、稳定性及实际样品检测效果进行评价。结果显示，该体系经优化后稳定性良好，可在66 ℃ 恒温条件下，60 min内完成检测；DNA检测下限可达0.02 ng/μL，灵敏度与荧光定量PCR方法相同，比常规PCR方法高1个数量级；能快速、准确地对田间疑似样品进行检测，与荧光定量PCR方法的检出情况一致，没有漏检。结果说明柑橘溃疡病菌实时浊度LAMP检测方法操作简便、所需时间短，特异性与灵敏度高，为柑橘溃疡病菌的快速筛查提供较好的途径。 相似文献
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喷施乙烯利对‘HAES900’澳洲坚果果实脱落和品质的影响 总被引：3，自引：0，他引：3
为解决澳洲坚果采收难和采收成本高的关键问题,以‘HAES900’澳洲坚果成龄结果树为材料,在采收期分别喷施低浓度梯度(0.40、0.65、0.90 g/L)和高浓度梯度(0.80、1.30、1.80 g/L)的乙烯利溶液,对喷施乙烯利溶液后的落果率、果柄附着力和果实品质进行了调查和分析。结果表明,低浓度乙烯利对果实脱落有促进作用,但落果率达不到生产要求;喷施1.80 g/L的乙烯利溶液2周和4周后的落果率分别达到98.75%和100.00%,可满足生产要求;喷施浓度为0.80、1.30和1.80 g/L的乙烯利会使果柄附着力显著降低,且果柄附着力与落果率呈极显著负相关;果柄附着力可作为判断澳洲坚果适宜采收期的指标之一。采用本方法采收对壳果含水量、单壳果重、壳果平均横径、单果仁重、出仁率和一级果仁率等品质参数无显著影响,且可缩短澳洲坚果采收周期,降低采收成本。 相似文献
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柑橘黄龙病（Citrus Huanglongbing,简称HLB）是柑橘的毁灭性病害,柑橘感染后不仅导致叶片黄化,影响果实品质,而且会使树势减弱直至植株死亡。本研究以感染黄龙病和健康沙田柚[Citrus maxima (Burm.) Merr. cv. Shatian Yu]为材料,对比分析黄龙病树（HLB+）和健康树（HLB-）在叶片形态特征、果实品质、矿质元素等方面的差异,旨在掌握黄龙病对沙田柚树体和果实的影响,为促进柑橘黄龙病的防控提供理论参考。沙田柚黄龙病植株与健康植株相比,叶片面积减少28.13%,叶绿素a、叶绿素b和类胡萝卜素分别降低40.38%、44.00%和40.47%;果实外观着色异常且果实偏小,平均单果重下降45.62%,果皮变薄,种子败育增多,果实维生素C升高26.44%,达到显著水平,并且不同组织的多个元素发生显著变化。与健康植株相比,黄龙病叶片N和Ca元素分别减少19.00%和49.72%,果肉N元素减少18.00%,而果皮和果肉Ca元素显著升高;病树根、叶片、果皮和果肉S元素均显著低于健康树。病树叶片B和Cu元素分别降低了35.07%和54.45%,果皮Cu元素显著降低了42.96%,果肉Zn元素显著升高了41.30%。黄龙病严重影响了沙田柚叶片形态和果实品质以及矿质元素代谢,应高度重视提高沙田柚果园的黄龙病防控管理水平。 相似文献
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Hajivand Shokrollah Thohirah Lee AbdullahKamaruzaman Sijam Siti Nor Akmar Abdullah 《Crop Protection》2011,30(5):521-525
Huanglongbing (HLB), also known as citrus greening disease, has spread to and is seriously threatening the citrus industry in more than 40 countries. The HLB pathogen is a phloem limited bacteria, Candidatus Liberibacter spp. There is little information pertaining to the effects of different citrus rootstocks and interstocks against HLB in Citrus reticulata. The objective of this study was to evaluate the beneficial effects of different combinations of citrus rootstocks and interstocks against HLB using side grafting. There were no symptoms of HLB when C. grandis was used as rootstock with C. hystrix as the interstock and vice versa six months after inoculation. However, C. Liberbribacter asiaticus was detected in the scion using second PCR amplification. A high rate of disease severity was observed when C. aurantum was used as rootstock and C. aurantifolia as the interstock and vice versa. This study showed that C. Liberibacter asiaticus can be detected by conventional PCR and characteristics of their detrimental effects include low rate of vegetative growth and reduction of dry matter, root dry matter, plant height and stem diameter. 相似文献
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Huanglongbing (HLB), one of the most devastating citrus diseases in the world, was detected in Mexico in 2009. Currently, HLB is associated with the bacteria Candidatus Liberibacter spp., although several phytoplasmas have been found from trees showing HLB-like symptoms in Brazil and China. The aim of this study was thus to determine if, in addition to ‘Ca. L. asiaticus’ (CLas), phytoplasma species are also associated with HLB-like symptoms in citrus groves of Mexico. Citrus plants exhibiting symptoms such as diffuse chlorosis, blotchy mottle and vein yellowing were collected in the Mexican States of Nayarit, Colima and Sinaloa between August 2011 and September 2012. Samples were then evaluated for phytoplasmas and CLas by PCR, using primers that respectively target the genes for the 16S ribosomal RNA and 50S ribosomal protein of the β operon (rplA-rplJ). Out of 86 HLB-symptomatic citrus plants, 54 were positive for CLas, 20 were positive for phytoplasmas, 7 were found in mixed infections with both pathogens and 19 samples were negative for CLas and phytoplasmas. Actual and virtual RFLP analyses of the 16S rDNA sequences enabled us to classify two HLB phytoplasma strains as members of the aster yellows group (16SrI) ‘Candidatus Phytoplasma asteris’, which was confirmed by phylogenetic analysis. The HLB phytoplasma strain identified from Nayarit (HLBpc-Nay-IB) belongs to subgroup B (16SrI-B), and the strains identified from Colima (HLBpc-Col-IS) and Sinaloa (HLBpc-Sin-IS) belong to subgroup S (16SrI-S). The partial ‘Ca. L. asiaticus’ rplA-rplJ gene sequences were 100% identical to the ‘Ca. L. asiaticus’ strains isolated from several countries affected by HLB. These results confirm the association of ‘Candidatus Phytoplasma asteris’ with HLB-like symptoms in citrus groves in Mexico. Nonetheless, further studies are required to fully describe the ‘Ca. L. asiaticus’ and ‘Ca. P. asteris’ interactions in citrus, which will greatly assist the design of efficient management strategies. 相似文献
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Huanglongbing (HLB) is the most devastating disease of citrus worldwide. It is caused by bacteria of the genus ‘Candidatus Liberibacter’ and transmitted by two psyllid species, the Asian citrus psyllid (ACP) Diaphorina citri, and the African citrus psyllid Trioza erytreae. Considerable research has been conducted toward developing and implementing HLB and ACP management strategies. With respect to ACP control, of interest is that reports indicate guava, Psidium guajava, can be repellent to ACP. We conducted research to further evaluate repellency of guava to ACP. In one set of experiments, guava oil from five Brazilian guava cultivars (‘J3’, ‘Pedro Sato’, ‘Século XXI’, ‘Thailand’ and ‘Paluma’) was extracted from leaves (immature and mature) by hydro-distillation in a Clevenger-type apparatus and evaluated for psyllid repellency. In a second set of experiments, repellency of guava leaves to ACP was investigated using leaves (immature and mature) from two guava cultivars in Florida, ‘Pink’ and ‘Thai White’. In each set of experiments, repellency was evaluated by releasing ACP adults into a cage with two large vials, one containing a young flush shoot (= immature leaves) of Murraya exotica (a favored host plant of the psyllid, the flush of which is highly attractive to ACP) and one with M. exotica flush and the test material of interest (guava oil, immature guava leaf or mature guava leaf). The adults were free to move throughout the cage and into the vials, and the number of psyllids in each vial was counted after 24 h. The results showed that all guava materials tested had at least some repellency to ACP. Mature leaves tended to have a greater repellent effect than immature leaves. Each of the five oils exhibited repellency. A report in the literature suggested that sulfur compounds associated with guava may be responsible for ACP repellency. Interestingly, the five guava oil extracts we studied were repellent to ACP but none contained any sulfur compounds. Identification of the constituents responsible for repellency could lead to new ACP management tactics. 相似文献
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通过调查嫁接在8种砧木上的砂糖橘的生长指标,分析叶片、枝条解剖结构及叶片中过氧化物酶(POD)、生长素氧化酶(IOD)活性,探讨树势与解剖结构和酶活性的关系。结果表明:以枳壳、粗柠檬和枸头橙为砧木的砂糖橘树势较强,红黎檬次之,酸橘、枳橙、红橘和砂糖橘(本砧)较弱;各指标与树势的相关性分析结果发现,叶片的海绵组织厚度与株高和树冠体积呈显著负相关,栅海比与树冠体积呈显著正相关;枝条的导管密度与株高和树冠体积均呈显著负相关;叶片POD活性与株高和树冠体积均呈显著负相关,IOD活性与秋梢长度呈显著负相关,其余无显著相关性。叶片中较低的栅海比、较高的海绵组织厚度和POD活性与枝条中较高的导管密度是影响树体矮化的重要因素。 相似文献
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Effect of chemical treatments on ‘Candidatus Liberibacter asiaticus’ infected pomelo (Citrus maxima)
Huanglongbing (HLB), also known as citrus greening, is one of the most destructive diseases affecting Rutaceae plants in many parts of the world. HLB is associated with three species of ‘Candidatus Liberibacter’ with ‘Ca. L. asiaticus’ (Las), being the most widely distributed bacterium in Thailand and Asia. The effectiveness of chemical treatment via trunk injection was evaluated in Las-infected pomelo (Citrus maxima) trees using quantitative real-time polymerase chain reaction. Our results demonstrated that a mixture of streptomycin (250 mg/L), ampicillin (2.5 g/L), penicillin G (2 g/L), and Bacicure® (2 g/L) provided the highest efficiency in reducing and suppressing the Las-bacterium population indicated by the mean cycle threshold (Ct) values from 20.8 (≈7.2 × 107 cells/g of plant tissue) to 36.6 (≈2140 cells/g of plant tissue) in greenhouse experiments, and from 19.4 (≈1.8 × 108 cells/g of plant tissue) to 37.8 (≈969 cells/g of plant tissue) in the field experiments. In addition, our strategies remained therapeutically effective for one year. Finally, response of Las-infected pomelo to chemical treatment was elucidated using transmission electron microscopy. 相似文献
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Spraying citrus (lime; Citrus auranticola (Christm.) Swing.) plants with clay suspensions containing kaolin or mixtures of kaolin and bentonite (montrorillonite) markedly reduced the rate of natural colonization by winged spiraea aphids (Aphis citricola van der Goot). The reduced colonization seems to be caused by the white coating of clay deposited on the leaves. Bentonite increases the adhesion of the clay suspensions on the leaves. These results suggest that clay suspensions may provide an ecologically acceptable control method for aphids, particularly under dry conditions. 相似文献
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Citrus variegated chlorosis (CVC), caused by the xylem-limited bacterium Xylella fastidiosa subsp. pauca (Xfp), is a damaging disease of sweet oranges (Citrus sinensis (L.) Osbeck) in several citrus production areas of South America. CVC was first identified in sweet orange orchards in the Northwest region of São Paulo State, Brazil. Transmission of Xfp from seed of CVC infected sweet orange fruit to seedlings has been reported. However, Xfp has not been reported to infect or cause CVC in lemon (Citrus limon (L.) Burm. f). Therefore, the objectives of this study were 1) to further evaluate the potential for vertical transmission of the bacterium through sweet orange seeds originating from symptomatic fruits to sweet orange seedlings and 2) to examine lemon trees and seeds for PCR detection of Xfp. Based on our evaluations, Xfp was not detected by PCR in leaves and seeds of different lemon cultivars surrounded by sweet orange orchards with high incidence of CVC. Furthermore, we could not detect with PCR that Xfp is vertically transmitted through sweet orange seeds to seedlings of sweet orange even from fruits with typical CVC symptoms. Hence, in this study and with the cultivars tested, Xfp was not confirmed by PCR detection to be transmitted via infected seeds from fruits of Citrus spp. even in areas where CVC is endemic nor was lemon found to be a natural host of Xfp. 相似文献
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Among the recommended measures for citrus Huanglongbing (HLB) management, the systematic elimination of symptomatic trees is the most argued and difficult to be accepted and accomplished by citrus growers. Elimination of recently affected HLB trees represents a short term yield loss and cost increase due to the need of frequent inspections and removal operations. This work aimed to evaluate the effect of different frequencies of inoculum reduction applied at individual citrus blocks scale (or local inoculum reduction) on HLB temporal progress. Eight experiments were carried out in new planted and older citrus blocks with 504–1290 trees/plot. In all experiments, inspections to detect symptomatic trees were done in a fortnightly or monthly frequency. The treatments of frequencies of local inoculum reduction varied from fortnightly to 6 months. Annual disease progress rate was estimated by logistic model for each plot. No difference on HLB progress rates among treatments was observed, except in experiments 1 and 3 where less frequent tree removal resulted in higher disease progress rate. This ineffectiveness of local inoculum reduction on the disease progress rate was explained by the higher weight of primary spread on HLB epidemics than the secondary spread within plots associated with small size and narrow shape of treated plots (except for experiments 1 and 3), high dispersal capacity of HLB-insect vector among plots and groves, and strong control of psyllid within the plots (except for experiment 1, with poor insecticide spray program). Also, the high amount of inspections to detect symptomatic trees before the eradication treatment, which reduced the escapes (asymptomatic and non visual detectable diseased trees) contributed for these results. It is important to note that these results were obtained with only small citrus plots (0.8–2.9 ha) and they cannot be extended to larger groves and farms amenable to HLB management by the symptomatic tree removal and vector control. 相似文献
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The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an important pest of citrus in the United States of America primarily because it vectors ‘Candidatus Liberibacter asiaticus’, the bacterium putatively responsible for Asiatic huanglongbing (HLB). Asiatic HLB is considered one of the most serious diseases of citrus. In the United States where Asiatic HLB was first found in the state of Florida, vector control is considered an essential component to mitigate pathogen infection and spread of the disease. Therefore commercial citrus growers in Florida have adopted intensive insecticide programs to manage psyllid populations. However, the repetitive use of insecticides for ACP control is expensive and interferes with biological control of ACP and other citrus pests. As an alternative to insecticides, reports from Vietnam indicated that infestations of ACP in citrus (and consequently incidence of HLB) were reduced when citrus was interplanted with white guava, Psidium guajava L. Speculations were that guava volatiles reduced ACP infestations in citrus by either repelling ACP or interfering with ACP ability to locate and infest citrus grown next to guava. We present the results of two studies conducted in Florida (where both ACP and HLB occur) to assess ACP infestations and HLB incidence in citrus interplanted with either white or pink guava compared to infestations and disease incidence in citrus grown as a monoculture, both in orchards and nurseries. In the field study, the effect of guava on ACP infestations was assessed alone and in combination with insecticide or oil applications. Significant reductions in ACP infestations in citrus interplanted with pink guava were identified, but there was no reduction in citrus interplanted with white guava. The effect of pink guava on ACP infestations could be investigated further. However, intercropping citrus with either white or pink guava did not prevent the introduction and spread of HLB. Conclusions from field studies regarding guava as a management tactic against ACP were difficult to make due to persistent nematode problems and freeze damage to guava, which could have interfered with the production of guava volatiles responsible for deterring ACP infestations. Conversely, citrus nursery trees interspersed with guava did show reduced HLB incidence and disease progression over time. However, vector and disease reduction resulting from guava intercropping in citrus nurseries was not adequate to recommend it as a management strategy. 相似文献