为揭示外来入侵植物长刺蒺藜草Cenchrus longispinus能够在贫瘠沙性土壤中快速生长、定殖的入侵机制,利用传统功能微生物筛选培养法、16SrDNA高通量测序技术及细菌基因组重复序列PCR(genome repetitive sequence PCR,rep-PCR)基因指纹图谱技术分析其根际土壤中解磷细菌的丰富度及多样性,并与本地伴生植物冰草Agropyron cristatum和狗尾草Setaria viridis根际土壤中的解磷细菌群落进行比较.结果显示,长刺蒺藜草根际土壤中解磷细菌的数量分别达到8.61×104 CFU/g和7.34×104 CFU/g,显著高于其余土壤样品.相较于空白对照土壤,长刺蒺藜草根际土壤中的解有机磷细菌数量增加最多,增加了 87.0％,冰草和狗尾草根际土壤中的解有机磷细菌数量则分别增加了 28.3％和15.2％;而长刺蒺藜草、冰草和狗尾草根际土壤中的解无机磷细菌数量分别增加了 36.7％、89.8％和24.5％.聚类分析结果表明,不同根际土壤中解磷细菌之间没有共有的优势聚类群.长刺蒺藜草根际土壤中2种解磷细菌群落的物种均匀度指数显著高于空白对照土壤和冰草及狗尾草根际土壤,而物种丰富度指数和Shannon-Wiener多样性指数均显著低于冰草及狗尾草根际土壤;其根际土壤中解无机磷细菌优势菌属经鉴定为金黄杆菌属Chryseobacterium.表明长刺蒺藜草在贫瘠沙土中对磷素的高效利用可能是其快速入侵并定殖的机制之一.

[目的]入侵植物少花蒺藜草在磷元素受限的贫瘠沙质土壤中能够快速生长和种群扩张,形成单一优势群落.本文解析了少花蒺藜草在磷胁迫条件下对磷素的高效利用机制,以期为揭示其入侵机理提供理论依据.[方法]设置少花蒺藜草、冰草、狗尾草和空白对照4个处理,通过高通量测序技术,从土壤解磷微生物的角度分析各处理间土壤中解磷细菌的组成差异.[结果]少花蒺藜草入侵显著提高了土壤磷酸酶的活性和土壤解磷菌的群落多样性.PCA与UPGMA聚类结果表明,少花蒺藜草与狗尾草根际磷细菌物种组成相似性最大.LEfSe多级物种差异判别分析结果表明,少花蒺藜草根际显著富集且与其他处理有显著性差异的解磷菌类群为α-变形菌、链霉菌,其在少花蒺藜草对磷的吸收中可能起较为重要的作用.变形菌门、浮霉菌门和放线菌门与少花蒺藜草根际土壤中的全磷含量呈显著正相关,放线菌门与少花蒺藜草根际土速效磷含量有紧密联系.[结论]少花蒺藜草通过改变入侵地根际土壤的解磷菌群落结构间接影响根际土壤的磷素环境,从而利于自身生长.

Invasive plants can change soil microbial communities and therefore promote invasion. While vegetation restoration has been adopted in certain infested lands to curb the invasion of Solanum rostratum, changes in the composition and function of rhizosphere soil bacterial communities of the species before and after the restoration has not yet been reported. In this study, two vegetation combinations used in previous studies were selected as candidates:Astragalus adsurgens+Elymus dahuricus+Bromus inermis (T1) and A. adsurgens+Festuca arundinacea+Agropyron cristatum+Leymus chinensis (T2). Rhizosphere soil samples were collected from each combination (T1 and T2), a S. rostratum invaded area (SR), and the native plant (NP) control to analyze the bacterial community structure and diversity using 16S rDNA gene sequencing on the Illumina MiSeq platform. PICRUSt was further used to predict the functional abilities of soil bacterial communities. Results of 16S rDNA gene sequencing showed that both the Simpson and Chao1 indices were higher in the SR treatment than in the NP treatment, but neither reached a significant level, although both indices decreased significantly after vegetation restoration (T1 and T2; P<0.05). The relative abundance of Microvirga, Skermanella, and Sphingomonas from phylum Proteobacteria and Bryobacter from the phylum Acidobacteria were significantly lower in the SR treatment (P<0.05) when compared with the NP treatment and higher in restoration treatments (T1 and T2). The RDA analysis showed that soil organic matter (OM), total nitrogen (TN), total phosphorus (TP), total potassium (TK), and available potassium (AK) were important factors affecting the composition of the bacterial community. Based on the PICRUSt analysis of soil bacterial community functions, the relative abundance of gene families related to biosynthesis of amino acids, purine metabolism, pyrimidine metabolism, ribosome, and aminoacyl-tRNA biosynthesis were higher in the rhizosphere samples of the SR treatment than those of the NP treatment and reduced significantly after vegetation restoration (T1 and T2; P<0.05). The structure and function of rhizosphere soil bacterial community of S. rostratum and vegetation restoration were analyzed and provided a theoretical basis for the invasion mechanism and ecological restoration of S. rostratum.

低温作为园艺作物中重要的非生物胁迫之一,直接影响到猕猴桃的生长发育,轻者造成减产,重者导致死树毁园.近年来,猕猴桃抗寒性的问题备受关注,其研究也取得了较大的进展.笔者从猕猴桃冻害成因、抗寒性鉴定方法、猕猴桃冻害调查分析、品种抗寒性评价、抗寒的生理和分子机制研究以及防寒预防措施等方面进行了系统归纳和总结,同时展望了猕猴桃抗寒性重点研究方向.

近年来我国猕猴桃产业发展迅速,产业发展潜力很大,但由于起步较晚、主导品种不明确、管理技术体系落后、质量标准体系不完善等原因,仍然存在诸多问题.主要问题包括:(1)尽管采收面积和产量均位居世界第一位,但单位面积产量低,而且生产总量占水果总量的比例仍然很小;(2)果实品质较差,进口单价始终高于出口单价,进出口贸易逆差明显.笔者通过对国内外猕猴桃生产、贸易数据的统计分析和产业调研,总结产业发展现状,梳理出我国猕猴桃产业存在的主要问题,并分析产生的原因,为促进我国猕猴桃产业健康发展提出对策及建议.

印加孔雀草(Tagetes minuta L.)入侵对生态系统和生物多样性造成危害,从土壤微生态学的角度探究印加孔雀草入侵对土壤细菌群落结构和多样性的影响,有助于深入揭示其入侵导致生态系统退化的机制.采用第二代高通量测序技术,以万寿菊(Tagetes erecta L.)为对照植物,设置不同植物的处理(裸土CK、万寿菊Te、印加孔雀草与万寿菊混种TmTe、印加孔雀草Tm),比较了各处理中土壤细菌群落结构的差异.结果表明:(1)TmTe的Ace指数显著低于CK、Tm且Chao指数显著低于CK,Tm的Shannon指数显著高于CK且Simpson指数显著低于CK,混种处理细菌群落丰富度最低,印加孔雀草单优群落处理群落多样性最高;(2)4个处理共有的OTUs为3169个,3个植物处理中,TmTe的细菌群落数最低,为3814个OTU,Tm细菌群落数最高,为4110个OTU;(3)相对丰度最高的前5个门分别是变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)、绿弯菌门(Chloroflexi)和芽单胞菌门(Gemmatimonadetes),在各处理中所占比例之和皆为80％以上;(4)放线菌门、硝化螺旋菌门(Nitrospirae)、变形菌门、拟杆菌门(Bacteroidetes)、绿弯菌门以及芽单胞菌门与土壤全钾含量呈显著正相关(P<0.05).蓝细菌门(Cyanobacteria)与环境因子之间的关系不同于其他菌门,相关性各有不同,但差异不显著.多囊粘细菌科(Polyangiaceae)、侏囊菌科(Nannocystaceae)、念珠藻科(Nostocaceae)等8个科的10个OTU类群共同存在于Tm vs CK和TmTe vs CK但不属于TmTe vs CK,表明其在印加孔雀草入侵过程中起着重要作用.该研究为揭示印加孔雀草入侵对土壤微生态影响机制提供了科学依据.

外来入侵植物会影响入侵地土壤氮库结构,研究外来植物与土壤氮转化的关系可以为揭示其入侵机制提供理论依据.以中国北方农牧交错带大面积发生的入侵植物少花蒺藜草为研究对象,选取裸地及本土植物鹅观草样地作为对照,研究少花蒺藜草入侵与外源氮对土壤氮转化速率的影响,以期从土壤氮转化速率的角度探讨少花蒺藜草的入侵机制.结果表明:与裸地及本地植物鹅观草样地相比,少花蒺藜草入侵地土壤氮净矿化速率增加;在分蘖期前(6—7月),土壤硝化速率增加、氨化速率降低;自分蘖开始至枯萎(8—10月),土壤硝化速率降低、氨化速率增加.添加NH4+-N或NO3?-N对整体的氮转化速率水平有影响,并使分蘖期后少花蒺藜草入侵地的氮矿化速率降低,但不改变分蘖前后三样地间硝化和氨化速率的大小关系.与净硝化速率及净氨化速率的关联性大小顺序为:添加外源氮处理>少花蒺藜草入侵>交互效应.与净矿化速率的关联性大小顺序为:添加外源氮处理>交互效应>少花蒺藜草入侵.添加外源氮更有利于裸地及本地植物鹅观草样地的氮矿化作用.少花蒺藜草在低氮素含量环境中表现出的生长优越性揭示了其适应沙质草地生态系统的一种入侵机制.

空心莲子草(Alternanthera philoxeroides)是一种多年生的全球性恶性杂草,破坏入侵地生物多样性,给航运及水产养殖业带来巨大损失.利用生物防治可以有效控制空心莲子草(Alternanthera philoxeroides)的扩散蔓延,是国内外的研究热点之一.空心莲子草叶甲(Agasicles hygrophila)是从美国引入的专食性天敌昆虫,对空心莲子草有很好的防治效果,且具有生态环保性良好、投入低、防效长等特点.天敌昆虫的释放量可显著影响防控效果,有关其最佳释放量的研究对实际应用具有重要指导意义.依托空心莲子草天敌工厂,采用环境条件控制试验,对空心莲子草的种群密度、植株形态、叶绿素含量、生物量等生物学和生理生化指标进行测定,结合对各种条件下空心莲子草叶甲种群数量的分析,研究了不同天敌释放量(0～8对·m?2)对空心莲子草的防治效果.结果表明,在初始种群密度为40 stems·m?2条件下,随着释放量的增加,空心莲子草叶甲成虫和羽化孔的数量均呈现先增加后减少的趋势,而卵、各龄幼虫、蛹的数量变化规律各不相同;空心莲子草的茎密度、生物量(湿质量、干质量)均随天敌释放量增加而逐渐降低,而节间距、茎直径等形态指标则呈现先降低后增加的趋势.研究结果显示,释放4对空心莲子草叶甲可达到最佳防治效果.在此释放量下,空心莲子草叶甲羽化孔数量和成虫数量均达到最高,空心莲子草种群密度最低,测得的节间距和茎直径最短,叶片中叶绿素含量较低,生物量最少.进一步分析表明,该释放量既能保证空心莲子草叶甲的稳定繁育和数量增加,又可获得对空心莲子草最佳的取食和控制效果,具有成本低、效率高的特点.试验结果可为进一步优化空心莲子草叶甲的繁育和释放技术提供理论依据.

Alternanthera philoxeroides is an typical alien invasive amphibious perennial herbaceous plant with a wide range of ecological adaptability and strong asexual reproduction ability. In this study, to further reveal the main survival strategies of A. philoxeroides in different habitats,we tried to explore the difference on the phenotypic plasticity and nitrogen migration amount of A. philoxeroides in three different habitats including terrestrial(I),amphibious(II)and aquatic(III)environment.The results showed that there were significant differences in biomass of different organs and nitrogen migration amount of A.philoxeroides in different habitats. Importantly, nitrogen migration amount was significant difference (P<0.05), which were all reflected to II>III>I in three different treatments. The average growth rate of habitat II was 23.32% higher than III and 54.49% higher than I, respectively. The total biomass of A. philoxeroides was highest in habitat II but lowest in habitat I, respectively. The distribution of biomass underground part showed a significant negative correlation with water content of habitat, which wasⅠ>Ⅱ>Ⅲ. The distribution of average biomass in stem was 15.57% higher than that in leaf. In different habitats. The plant height and internodes length of A. philoxeroides both were reflectedⅡ>Ⅲ>Ⅰ.Therefore,it displays stronger phenotypic plasticity and adaptability to heterogeneous environment in amphibious habitat base on the difference of the nitrogen migration quantity and distribution pattern and biomass of different organs of A. philoxeroides under different habitats. This research reveals the clonal plant A. philoxeroides has stronger invasive ability in amphibious habitats than other two habitats. It will give great helpful to provide theoretical basis for the prevention and control of A.philoxeroides.

Kiwifruit originated in China and later introduced to international market by New Zealand.As one of the main producers of kiwifruit in the world,kiwifruit industry in China has rapidly expanded over the last decade.Pathogen is one of the key factors affecting sustainable development of kiwifruit industry.Plant pathology in kiwifruit is mainly focused on bacterial and fungal causing diseases,such as bacterial canker caused by Pseudomonas syringae pv.actinidiae.Over the last few years,outbreaks of bacterial canker on Actinidia chinensis and A.deliciosa have caused a huge impact on international kiwifruit industry.For viruses in kiwifruit,our knowledge of them is still limited.Virus which can be latent is a hidden danger in the fruit production.Mounting evidence indicates that kiwifruit viruses are widely present in fields.The first incidence of virus in kiwifruit was reported in the year of 2003 by scientists from New Zealand,who detected the presence of apple stem grooving virus in kiwifruit plants imported from China.To date,fifteen viruses have been reported worldwide,including two tobamoviruses,Ribgrass mosaic virus (RMV) and Turnip vein clearing virus (TVCV);a tombusvirus,Cucumber necrosis virus (CNV);a novel potexvirus,Actinidia virus X;a capillovirus,Apple stem gooving virus;a alfamovirus,Alfalfa mosaic virus;a cucumovirus,Cucumber mosaic virus;a nepovirus,Cherry leaf roll virus;a anulavirus,Pelargonium zonate spot virus;two vitiviruses,Actinidia virus A and Actinidia virus B;a citrivirus,Actinidia citrivirus;a novel emaravirus Actinidia chlorotic ringspots associated virus;a tospovirus,Tomato necrotic spot tospovirus;and a novel virus belonged to the family Closteroviridae.However,only few of them are documented in details.It largely remained unclear how these viruses can affect kiwifruit production.Most of these viruses are non special-ists infecting a wide range of hosts.They are easily transmissible via multiple ways,by grafting,vectors and mechanical transmission.Symptoms include vein clearing,necrotic ringspots,chlorotic mosaics and mottling on leaves,but can be latent or show no obvious symptoms.It has been reported that diseases induced by Cherry leaf roll virus and Pelargonium zonate spot virus cause severe damages on kiwifruit production in orchards.A group of viruses are kiwifruit adapted as they either infect kiwifruit only or to limited host range,such as Actinidia citrivirus,Actinidia virus A and Actinidia virus B,Actinidia chlorotic ringspots associated virus,Tomato necrotic spot tospovirus.By now,there are five viruses described in China,including Actinidia virus A,Actinidia virus B,Actinidia citrivirus,Tomato necrotic spot tospovirus and Actinidia chlorotic ringspots associated virus.Recently,we carried out a survey of virus infection of kiwifruit in Henan province.A total of 68 kiwifruit samples were tested by RT-PCR.Actinidia citrivirus was the only virus detected out of 13 viruses,with an incidence rate of 17.6％.Several diagnostic tools are used for virus detection,such as herbaceous indicators,electron microscopy,ELISA and RT-PCR.Herbaceous indicators are old fashioned method for virus detection which is easy to handle,but it usually takes long time to show symptoms.It is less accurate if infected plants are symptomless or virus infection is latent.ELISA has been applied for plants virus detection since 1970s,and now it commonly used for testing.This serologic method has high specificity which is more accurate and faster than the approach of herbaceous indicators.However,the main limitation for detecting by ELISA is a requirement of specific antibody against a particular virus.Nowadays,RT-PCR is more frequently used for virus detection,which is highly specific and sensitivity than ELISA.It also can be used for detection of viroids.China is one of the main producing countries of kiwifruits.Lack of understanding of kiwifruit viruses and their related diseases poses potential threats on kiwifruit industry.Future research should investigate the potential impacts of virus infection on kiwifruit industry and expand our knowledge of molecular mechanisms of virus infection and transmission.With rapid development of kiwifruit industry,we should raise awareness of kiwifruit viruses of growers which will help to increase understanding about the diseases in kiwifruit production.Establishment of rapid detection technology will further progress on research of kiwifruit viruses.Moreover,it is necessary to promote scientific and effective field management for improving disease control,which will minimise and prevent the spread of virus.There is a need of selecting varieties resistant to diseases,improving the quality of kiwifruits available on the market.These strategies should be implemented to ensure a safe,effective and sustainable development of kiwifruit industry which will bring social and economical benefits to our growers and consumers.In this review,it describes the viruses of kiwifruit and discusses their potential damages to kiwifruit production.This paper summarizes current research progress of viruses of kiwifruit in China,and finally reviews routine diagnostic tools commonly used for virus detection in kiwifruits.

[Objective]In order to obtain the knowledge of genetic variation and relationship of various cultivars in the genus Actinidia Lindl.,the pollen morphological characteristics of three Actinidia species were investigated.[Methods] Scanning electron microscopy was used to observe pollen morphology of thirty samples collected from three cultivated Actinidia species,A.deliciosa,A.chinensis and A.arguta.Parameters of pollen grains such as the length of polar axis,length of equatorial axis,length of colpus and width of colpus were measured and analyzed using an image software (Imagepro-Plus).[Results] The pollens of A.deliciosa,A.chinensis and A.arguta were in the form of a single grain,being prolate or perprolate.Only one sample ofA.deliciosa contained the prolate-shaped pollen grains whereas all samples of A.chinensis contained the perprolate-shaped pollen grains.A total of ten samples of A.arguta were included in this study,four of them contained the prolate-shaped pollen grains while others contained perprolateshaped pollen grains.Each pollen grain contained three colpi which elongated along the polar axis till they reached the ends.One or two colpi could be observed in the equatorial view,whereas all three corpi that were furrows in trifid circular could be seen in the polar view.The results of the measurements of A.deliciosa pollen grain were as follows:The length of colpus was 18.08-31.48 μm and the coefficient variation was 9.59％.The width of colpus was 4.65-11.42 μm and the coefficient variation was 12.40％.The length of polar axis was 21.54-36.05 μm and the coefficient variation was 7.6％.The length of equatorial axis was 9.60-17.66 μm and the coefficient variation was 10.01％.The ratio between the polar and the equatorial axis was 1.65-3.05 and the coefficient variation was 9.68％.The pollen size was 244.90-608.52 μm2 and the coefficient variation was 15.06％.The results of the measurements of A.chinensis pollen grain were as follows:The length of colpus was 14.09-24.96 μm and the coefficient variation was 14.00％.The width of colpus was 4.09-9.37 μm and the coefficient variation was 15.88％.The length of polar axis was 15.60-30.11 μm and the coefficient variation was 11.17％.The length of equatorial axis was 8.85-17.87 μm and the coefficient variation was 11.80％.The ratio between the polar and the equatorial axis was 1.26-2.65 and the coefficient variation was 9.93％.The pollen size was 182.58-443.18 μm2 and the coefficient variation was 21.52％.The results of the measurements of A.arguta pollen grain were as follows:the length of colpus was 16.34-30.06 μm and the coefficient variation was 11.62％.The width of colpus was 6.11-11.23 μm and the coefficient variation was 14.13％.The length of polar axis was 18.66-32.11 μm and the coefficient variation was 9.21％.The length of equatorial axis was 8.76-18.42 μm and the coefficient variation was 10.79％.The ratio between the polar and the equatorial axis was 1.33-2.68 and the coefficient variation was 10.90％.The pollen size was 166.62-547.07 μm2 and the coefficient variation was 16.70％.There are three types of surface ornamentation in Actinidia pollens.(1) The corrugated ornamentation was covered with a smooth surface composed of irregular strips.Sixteen samples showed corrugated ornamentation,which accounted for 53.33％ of the total samples used in this study.Among them,five samples belonged to A.deliciosa,which accounted for 38.46％ of A.deliciosa pollens.Five samples belonged to A.chinensis,which accounted for 71.43％ of A.chinensis pollens.Seven samples belonged to A.arguta,which accounted for 70％ of A.arguta pollens.(2) The pollen with warty ornamentation was covered by regular or irregular block like protrusions.The size of these protrusions was irregular.Eleven samples showed warty ornamentation,which accounted for 36.67％ of all samples included in this study.Eight samples belonged to A.deliciosa,which accounted for 61.54％ of A.deliciosa pollens.Two samples belonged to A.chinensis,which accounted for 10％ of A.chinensis pollens.One sample belonged to A.arguta,which accounted for 10％ ofA.arguta pollens.(3) The surface of pollens with granular ornamentation was distributed with particles or in the pattern of granules.Three samples showed granular ornamentation,which accounted for 10％ of all samples included in this study.The samples with granular ornamentation belonged to A.arguta which was originated from the province of Heilongjiang.It accounted for 30％ of A.arguta pollens.[Conclusion] There was a certain degree of conservation in pollen morphology and size of Actinidia pollens derived from the same species or environmental background.Overall,the pollen size of A.deliciosa was the largest among these species,followed by A.arguta and A.chinensis.The length the polar axis,length of equatorial axis,length of colpus and width of colpus,of A.chinensis were lower than those of A.deliciosa.Hence,the morphological differences of pollens between A.chinensis and A.deliciosa would provide some evidence for taxonomy of these species.