[目的]本研究旨在研究福建南平地区芦柑(Citrus reticulata)植株根际土壤细菌群落,并分析黄龙病对其细菌群落的影响,为南平地区芦柑黄龙病的防控提供科学依据.[方法]采用五点法采集了健康和黄龙病发病的芦柑植株根际土壤样本,通过扩增子测序技术和生物信息学方法,深入研究了黄龙病发病芦柑根际土壤细菌群落的多样性和组成变化,分析了土壤理化因子与细菌群落的关联性.[结果]研究结果表明,黄龙病发病的芦柑植株根际土壤细菌群落的多样性略高于健康植株.黄龙病发病芦柑根际土壤中的变形菌门相对丰度明显升高,而放线菌门相对丰度显著降低.在属水平上,与健康植株相比,黄龙病发病芦柑植株根际土壤细菌群落中蔷薇属和嗜酸性杆菌属的相对丰度显著增加,与速效钾、有效磷以及有机质呈现显著负相关,而与pH值呈现显著正相关.相反地,康奈斯氏杆菌属和褚氏杆菌属的相对丰度明显低于健康植株,并与速效钾、有效磷以及有机质呈现显著正相关,同时与pH值呈现显著负相关.[结论]黄龙病菌感染改变了柑橘土壤理化特性,并显著减少根际土壤中有益细菌的相对丰度,从而导致了芦柑植株根际细菌群落的多样性和组成出现显著变化.与此同时,黄龙病发病的芦柑植株可能通过招募固氮和促进植物根际生长的有益细菌来对抗病原菌的侵害.

亚洲柑橘木虱Diaphorina citri Kuwayama是柑橘黄龙病的传播媒介.本文利用SteREO Discovery V20体视显微镜对亚洲柑橘木虱成虫内生殖系统进行解剖观察,并探索了亚洲柑橘木虱雌雄成虫内生殖系统的形态变化规律.结果表明:雄虫内生殖系统由1对精巢、1对输精管、1个精泵、1个射精管、1对附腺和1个贮精囊组成.雌虫内生殖系统由1对卵巢、1对侧输卵管、1个中输卵管、2个附腺、1个黏腺和1个受精囊组成.交配前期和交配期的雄虫精巢饱满,精巢在交配后期明显萎缩.交配期和交配后期的雄虫贮精囊都明显大于交配前期的贮精囊.雌虫受精囊在交配前期、交配期和交配后期依次增大,交配前期的受精囊呈不饱满状态,交配期和交配后期受精囊呈饱满状态,内有白色精包.交配后期的雌虫卵巢内有大量成熟的橙黄色卵.

亚洲柑橘木虱Diaphorina citri Kuwayama是柑橘的毁灭性病害—黄龙病(huanglongbing,HLB)的传播媒介,是柑橘生产中最重要的害虫.本文综述了亚洲柑橘木虱的起源、分布和扩散情况,揭示中国亚洲柑橘木虱由南向北的扩散规律,为有效防治木虱、阻止黄龙病进一步蔓延传播、保障我国柑橘产业的健康发展提供依据.

Wolbachia can profoundly influence the survival,reproduction,and defenses of insect hosts.These interactions could potentially be harnessed for managing pests or insecttransmitted diseases.Diaphorina citri Kuwayama is a phloem-feeding pest capable of transmitting the putative causal agent of citrus greening,Candidatus Liberibacter asiaticus (CLas).Like many insects,D.citri is also infected with Wolbachia (wDi).Recent studies indicate that the relative abundance of wDi could be associated with the abundance of CLas,and that wDi may contribute to regulating expression of phage lytic cycle genes in CLas,suggesting the need for better understanding of wDi biology in general.This study investigated the genetic diversity of wDi among D.citri in populations spanning eleven countries and two U.S.territories.Six Wolbachia genes,wsp,coxA,fbpA,ftsZ,gatB,and hcpA,were sequenced and compared across samples.Two prevalent wDi strains were identified across the samples,and screening of clone libraries revealed possible coinfection of wDi strains in specific populations.D.cirri mitochondrial cytochrome oxidase subunit Ⅰ gene (mtCOI) were more divergent between D.citri populations that were infected with different wDi strains or had different infection statuses (single infection vs.coinfection).While we could not eliminate the possibility that maternal transmission may contribute to such patterns,it is also possible that wDi may induce cytoplasmic incompatibility in their host.These findings should contribute to the understanding of wDi population ecology,which may facilitate manipulation of this endosymbiont for management of citrus greening disease worldwide.

Citrus is one of the top three fruit crops worldwide.Citrus production is facing an unprecedented crisis due to Huanglongbing (HLB,also known as citrus greening),which is the most devastating disease of citrus.HLB was first reported in Asia a century ago.HLB is associated with Candidatus Liberibacter asiaticus (Las),Ca.L.americanus (Lam),and Ca.L.africanus (Bové,2006),which belong to the gram-negative α-proteobacteria.Among them,Las is the most widely spread.Las and Lam are vectored by Diaphorina citri Kuwayama (ACP),whereas Laf is transmitted by Trioza erytreae.HLB and ACP are rapidly spreading to and having a devastating impact on citrus production in other citrusproducing areas such as Brazil,Caribbean counties,and the US.To date,HLB has been confirmed in 51 of the 140 citrusproducing countries.The major citrus-producing regions without HLB,such as the Mediterranean region and Australia,are at great risk for ACP establishment and HLB spread (Gutierrez and Ponti,2013).In addition,Trioza erytreae has been found in Spain and poses immediate threat of spread of HLB in the Mediterranean region.Thus,HLB has become a global problem.

柑橘木虱Diaphorina citri Kuwayama是柑橘黄龙病(huanglongbing,HLB)的重要传播媒介.为了利用灯光诱控技术防治柑橘木虱,本实验于室内条件下研究柑橘木虱对波长为360 nm、400 nm、440 nm、480 nm、520 nm、560 nm和600 nm的LED光源和不同光照强度趋光行为反应.结果 表明:柑橘木虱对7种单色光都有正趋向性.其中雌雄混合存在时对400 nm的紫光趋向性最强,其次是560 nm的绿光;单独处理时,雌成虫对400 nm的紫光趋性最强,其次是520 nm的绿光,雄成虫则是对520 nm的绿光趋性最强,其次是400 nm的紫光.在200 μw/cm2到1 000 μw/cm2的光照强度范围内,随着光照强度的增大,柑橘木虱雄成虫趋光行为逐渐增强,在光照强度为1 000 μw/cm2时趋光行为最强,但雌成虫趋光行为变化不明显.该研究表明:柑橘木虱雌雄成虫具有明显的正趋光性,且对光谱和光强的反应存在差异.这一结果可为柑橘木虱田间的灯光诱控提供实验依据.

黄龙病是全球广泛发生的毁灭性病害,柑橘木虱为其主要媒介昆虫.越南最早于上个世纪六十年代有相关报道.通过一些国际合作项目,越南对柑橘木虱和黄龙病进行了一系列研究并积极采取措施有效防控:包括消除病株、筛选抗病虫品种、改变种植密度和时间、化学防治与生物防治、作物间种、喷施矿物油乳剂、施用有机肥、使用无病苗和无病接穗并在运输过程中封闭保护等.其中控制黑臭蚁Dolichoderus thoracicus增殖黄猄蚁Oecophylla smaragdina、交错式间种番石榴以控制柑橘木虱和黄龙病值得中国借鉴和参考.

Bacillus thuringiensis (Bt) toxins are effective in controlling insect pests either through the spraying of products or when expressed in transgenic crops.The discovery of endophytic Bt strains opened new perspectives for studies aimed at the control of sapsucking insects,such as the Asian citrus psyllid Diaphorina citri Kuwayama (Hemiptera:Liviidae),a vector of"Candidatus Liberibacter spp.," associated with citrus huanglongbing (HLB).In this study,transloeation of endophytic Bt strains in citrus seedlings inoculated with Bt suspension delivered by soil-drench,and their systemic pathogenicity to D.citri nymphs were investigated.The pathogenicity of three wild-type Bt strains against D.citri third-instar nymphs was demonstrated.Among the 10 recombinant strains tested (each of them harboring a single cry or cyt gene),3 can be highlighted,causing 42％-77％ and 66％-90％ nymphal mortality at 2 and 5 d after inoculation,respectively.The isolation of Bt cells from young citrus shoots and dead nymphs,and PCR performed with specific primers,confirmed the involvement of the Bt strains in the psyllid mortality.This is the first report showing the translocation of Bt strains from citrus seedling roots to shoots and their potential to control D.citri nymphs that fed on these soil-drench inoculated seedlings.The Bt strains that caused the highest mortality rates have the potential to be used as bioinsecticides to control D.citri and the identified genes can be used for the production of transgenic Bt citrus.

黄龙病(huanglongbing,HLB)是华南柑橘产区最严重的病害之一,主要通过柑橘木虱和嫁接等方式传播,不同的感病方式对寄主的影响可能有所差别.本研究通过嫁接的方式,研究黄龙病对椪柑在感病早期和发病晚期转录组的影响.在早期(14 wpi),总共有6 467个基因出现了显著差异表达,而在晚期(22 wpi),总共有9 625个基因出现了显著差异表达.对差异表达的基因进行KEGG富集分析,发现14 wpi组的差异表达基因总共有14个通路出现了富集,而22 wpi组的差异表达基因总共有24个通路出现了富集.对8个差异表达的基因进行荧光定量PCR验证,结果表明这些基因在两个阶段的表达变化趋势与转录组的数据基本一致.本研究通过研究黄龙病不同发病阶段的差异基因表达,为探究黄龙病的发病机理提供了一定的理论基础.

[目的]亚洲柑橘木虱Diaphorina citri是传播柑橘最重要病害黄龙病(huanglongbing,Candidatus Liberibacter asiaticus)的媒介昆虫,树冠喷施园艺矿物油(horticultural mineral oil,HMO)可以减少其在柑橘上的取食和产卵.本研究旨在探索植物组织内残留的园艺矿物油如何影响亚洲柑橘木虱成虫的取食行为.[方法]采用直流型刺吸电位仪(DC-EPG Giga-8)记录亚洲柑橘木虱成虫12 h内在喷施不同浓度(0.25％,0.5％,1％和2％,v/v)HMO(nC24)乳剂和清水(对照)时柑橘嫩叶上的刺探和取食行为并转换为波形信号,分析比较各处理的波形参数.[结果]不同浓度HMO乳剂处理显著提高了亚洲柑橘木虱成虫在柑橘叶片上的C波(路径波)持续时间百分比,显著减少了E2波(韧皮部吸食汁液)持续时间百分比,而对D(口针第一次接触韧皮部组织),E1(韧皮部出现唾液分泌)和G(木质部吸食汁液)波持续时间百分比没有显著影响.HMO处理组C波的每成虫波形累积时间(WDI)显著长于对照组,而各浓度处理之间没有显著差异,但D波WDI明显短于对照组.随着HMO浓度的增加,E1,E2和G波WDI显著下降,2％ HMO处理组E1,E2和G波WDI明显低于其他浓度处理组.HMO乳剂处理明显减少了刺探次数;在HMO处理中,每成虫刺探次数和每成虫各波形次数均显著少于对照组,其中以1％和2％ HMO乳剂处理最少.HMO乳剂处理组np波(非刺探波)、D波、E2波的每成虫单次波形持续时间(WDE)均短于对照组,其中2％ HMO乳剂处理后,D,E1和E2波WDE显著短于其他浓度处理和对照.同时,2％HMO乳剂处理推迟了从口器接触叶片到第1次开始刺探的时间和从口器接触叶片到第1次刺探到韧皮部的时间.[结论]结果表明,2％ HMO乳剂显著减少亚洲柑橘木虱成虫在柑橘叶片上的取食次数和有效取食时间,同时还缩短了其在韧皮部分泌唾液和吸食汁液时间,因此可推荐矿物油用于柑橘黄龙病和亚洲柑橘木虱的综合防治体系.同时初步推断矿物油的作用机制可能是其进入植物气孔阻止植物挥发性物质的释放,抑制或掩盖柑橘叶片表面的挥发性物质从而减少了亚洲柑橘木虱在寄主上取食.