中国柑橘黄龙病病原菌两个原噬菌体超变异基因遗传多样性

【目的】通过原噬菌体区域高度变异的基因位点研究柑橘黄龙病病原菌亚洲种（‘Candidatus Liberibacter asiaticus’）的种群分化,探讨病原菌种群遗传多样性水平和遗传结构。【方法】基于2种原噬菌体类型（SC1和SC2）对应的超变异基因区域设计2对引物（Lap-TJ-F/Lap-TJ-R1和Lap-TJ-F/Lap-TJ-R2）,对中国不同柑橘产区的224个‘Ca. L. asiaticus’株系进行PCR检测和序列分析。【结果】PCR扩增的条带类型呈多态性,具有4种条带类型（SC1-1、SC1-2、SC2-1和SC2-2）,西南地区以SC1-1型为主,广东、广西地区以SC2-1型为主,福建、江西、浙江地区没有明显优势的扩增型。分析SC1-1和SC1-2对应序列表明,其差异系由于132 bp的卫星序列和24 bp的小卫星序列2种串联重复序列数不同引起,而SC2-1和SC2-2的差异系由原噬菌体内部基因重排引起。【结论】中国不同地理来源病原菌株系在原噬菌体区域具有较丰富的多态性,对该基因区域研究将有助于揭示中国‘Ca. L. asiaticus’种群的遗传多样性。     

基于PRiME HLB前处理技术的鸡蛋中四环素类药物的快速筛选方法研究

使用新型固相萃取小柱PRiC_1MEC_1 HLB处理鸡蛋样品,建立了一种鸡蛋中四种四环素类药物的简单、快速的筛选分析方法。鸡蛋样品经Na_2EDTA-Mcllvaine缓冲液提取,乙腈沉淀蛋白,PRiC_1MEC_1 HLB固相萃取柱净化,浓缩富集后,采用液相色谱法检测,外标法定量。PRiC_1MEC_1 HLB固相萃取法是简单的通过式净化处理方法,样品净化过程简单、快速、高效。方法最低检出限为50μg/kg,定量限为100μg/kg,土霉素、四环素、金霉素、多西环素4种四环素类药物在50~5000C_1ng/mC_1L范围内呈现良好线性,回收率满足分析筛选的要求。该方法可以有效起到快速筛选鸡蛋中四环素类药物残留的作用,具有较广的应用性。     

����ľʭ���о���չ

柑橘木虱(Diaphorina citri)主要危害柑橘等芸香科植物,传播黄龙病菌,给柑橘生产带来极大危害.从柑橘木虱的生物学及生态学特性、防治,柑橘木虱内生菌多样性、其对黄龙病菌的传播机制等方面进行综述,提出木虱寄主选择机理、专性传菌机制和抗性品种筛选是今后防治柑橘木虱的研究重点.     

小麦抗蠕孢菌叶枯病(HLB)遗传的初步研究

小麦蠕孢菌叶枯病(HLB)在我国已经成为影响小麦高产、稳产的重要病害之一。本文通过小麦抗、感品种杂交的F1、F2代群体对Bipolaris sorokiniana的抗病性差异,研究了小麦蠕孢菌叶枯病(HLB)的抗性遗传,发现豫麦17的抗病性是由数量性状基因控制的。经典数量遗传学分析表明豫麦17对蠕孢菌叶枯病的抗性是由2个以上基因控制,可能是3个基因。它与中国春组合的广义遗传力为67%。     

萜烯树脂乳液的研制

采用专用高分子表面活性剂研制了系列萜烯树脂乳液.研究结果表明,修正后的计算亲水亲油平衡值(HLB值)的方法可用于高分子表面活性剂中单体质量比的设计,萜烯树脂的HLB值被定为13.乳化中应添加助溶剂来降低萜烯树脂的熔化温度和时间.高分子表面活性剂的结构极大地影响萜烯树脂的乳化结果,本研究中高分子表面活性剂苯乙烯-聚丙烯酰胺-单体3(质量比1:0.6:0.2)用量为10%时能将萜烯树脂T-90、T-100和T-110乳化成稳定的乳液.     

柑橘黄龙病株分布边缘效应研究

根据柑橘园黄龙病植株与健康植株的二阶中心矩比值DR和方差检验来分析HLB的分布边缘效应,同时以病株与健康株的一阶方向矩比值LR和方差检验来判断HLB的主要入侵方位(N、S、E、W)。结果表明,当DR≥1且方差F显著性概率P<0.05时,HLB病株分布呈显著边缘分布倾向,由此说明HLB具有边缘侵入效应;当DR≤1且方差F显著性概率P<0.05时,认为HLB为内源性苗木带菌入侵;当DR≈1且方差F显著性概率P>0.05时,或因HLB初侵染或盛发期而无法判断HLB侵染源。另,DR≥1、|LR|≥1且方差分析均呈显著差异时,可依据|LR|在各方向的大小来判定HLB的主要入侵方向。近距柑橘园间HLB传播具有边缘侵入效应与方向性,在HLB疫区建园时需注意防范。     

土霉素处理对Valencia夏橙中淀粉及相关基因表达的影响

黄龙病(Huanglongbing,HLB)会造成柑橘韧皮部坏死堵塞,导致光合同化物运输不畅,淀粉大量积累。在感染HLB的4年生Valencia夏橙病株上分别注入0.1和0.2 g·株~(-1)土霉素(Oxytetracycline,OTC),90 d后运用qPCR检测,病株中HLB病原菌(Candidatus Liberibacter asiaticus,Las)含量均明显降低,且0.2和0.1 g·株~(-1) OTC处理的效果相当。I2/KI显色及LM观测表明,0.2 g·株~(-1) OTC处理后植株的淀粉含量从注射前的18.58μg·mm~(-2)减少至90 d的5.24μg·mm~(-2),而0.1 g·株~(-1)的处理90 d仅降至11.88μg·mm~(-2)。高效液相色谱(HPLC)检测结果表明,注射后90 d内,试验用浓度0.2 g·株~(-1) OTC在植株体内可降解至200μg·kg~(-1)以下。基因表达结果表明,注射0.2 g·株~(-1) OTC后30和90 d,淀粉合成及分解相关基因表达量均下降,其中淀粉合成相关基因AGPase表达量下降最显著,这与OTC注射后30和90 d叶片内淀粉含量下降结果一致。     

Boron availability and uptake in huanglongbing-affected citrus trees on a Florida entisol

Abstract

Florida sandy soils, particularly, Entisols are low in boron (B) and occasionally have B deficiency for citrus. A study was set-up at Citrus Research and Education Center, Lake Alfred, Florida, on a Candler fine sand to determine the availability and uptake of B in a high-density citrus planting of Huanglongbing (HLB)-affected trees. Boron was applied at 1.12?kg ha^?1 in three splits, at University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) recommended rate (1×), and at 2× the recommended rate using foliar and soil application methods. Soil samples were taken from soil surface to 60?cm depth in 15-cm increments within the irrigated and non-irrigated zones. Soil and leaf samples were analyzed for B using Mehlich III extraction method and acid digestion, respectively. Results showed the leaf B concentration for soil applied rate 1× was significantly higher (P?<?0.001) than that of foliar applied either at single or double rate but both were in the optimum range recommended by UF/IFAS. The sorption study revealed that there was no sorption (K_D < 0.2?L kg^?1) but K_D at 0–15-cm depth was 3× greater than that at 15–60?cm depths. The concentration of B in the leaf tissue remained in the recommended optimum critical range. Sorption coefficients showed negligible B sorption which means most applied B would be prone to leaching under heavy rains or saturated soil conditions on Florida sandy soils thus requiring judicious management for optimizing tree performance and sustaining environmental quality.     

郴州市柑橘黄龙病发生规律和综合防控措施

近年来柑橘黄龙病在郴州市呈流行趋势，本文对该病发生原因、危害面积和数量等进行了调查分析。指出柑橘黄龙病的防控在健全组织管理和加大培训宣传的基础上，通过采取严管种苗源头、精准联防统治、坚决清除病树等一系列综合防控技术措施，其暴发和蔓延得到了有效遏制。最后总结了黄龙病防控工作中的主要问题和不足之处，为其他地区柑橘黄龙病的综合防控提供参考。     

Rapid and quantitative detection of citrus huanglongbing bacterium ‘Candidatus Liberibacter asiaticus’ by real-time fluorescent loop-mediated isothermal amplification assay in China

Huanglongbing (HLB) is a devastating citrus disease that is associated with bacteria of the species ‘Candidatus Liberibacter asiaticus (Las)’ in China. All currently popular cultivars are susceptible to HLB, and there are no effective approaches to control the disease once the plants have been infected. Therefore, rapid and easy diagnostic tools are needed for maintaining clean nursery stock and inoculum removal strategies to control HLB. A real-time fluorescence loop-mediated isothermal amplification (RealAmp) targeting16S rDNA was developed for the rapid and quantitative detection of Las in China. The detection sensitivity of the RealAmp assay was approximately 1 pg/μl template DNA (equal to 2.4 × 10⁵ target DNA copies/μl) and no cross-reaction was observed with other pathogens or virus-free seedlings. Besides the quantitative detection using SYTO-9 fluorescent dye, an improved closed-tube visual inspection technique using SYBR Green I staining was developed for rapid screening of samples and minimize the risk of cross-contamination. The RealAmp assay is an alternative quantitative method, which would be used as a routine detection service for nursery materials in China.