Resistance to <Emphasis Type="Italic">Potato virus Y</Emphasis> in a Multitrait Potato Breeding Scheme without Direct Selection in Each Generation

In an experimental breeding scheme to improve late blight (Phytophthora infestans) and white potato cyst nematode (Globodera pallida) resistance of tetraploid potato over three generations of crossing and selection, 15 clones survived the final selection, and these were derived from 15 great-grandparents. There was no direct selection for resistance to Potato virus Y (PVY), but 14 out of the 15 great-grandparents were resistant to PVY and three had extreme resistance. Thirteen of the 15 descendants had PVY resistance and one extreme resistance. This was within the range expected for a random (unselected) sample from the genotypes of the great-grandparents. Hence, we found no evidence for any positive or negative association between PVY resistance and the attributes selected. The conclusion is that laborious selection is not required in every generation when many parents have PVY resistance, including some with more than one copy of a PVY resistance gene or resistance at more than one locus. However, in the future, determining the major virus resistance genes present in potential parents in each generation using diagnostic molecular markers would prevent susceptible × susceptible crosses being made and maximise the number of resistant × resistant ones.     

Validation of molecular markers for pathogen resistance in potato

DNA markers have a large potential to improve efficiency and precision of conventional plant breeding programmes based on marker‐assisted selection (MAS). In our study, we have evaluated the predictive abilities of the SCAR marker RYSC3 and the CAPS marker GP122₅₆₄ with regard to the PVY resistance genes Ry_adg and Ry_sto, respectively, and of marker TG689 linked to H1 conferring resistance to Globodera rostochiensis and marker HC associated with high levels of G. pallida resistance. The evaluations were made in 28 cultivars and accessions and in 219 progeny genotypes descending from ten different crosses. We observed in all evaluated cultivars and accessions the expected marker patterns according to their phenotypic classification into resistant and susceptible genotypes. However, in part considerable discrepancies were observed when analysing progeny of controlled crosses involving these resistance sources, particularly with respect to H1. Based on these results, practical aspects for the efficient implementation of marker‐assisted selection are discussed, which consider the genetic origin of the material, costs aspects and methodology applied.     

Occurrence of Potato virus Y strain PVYNTN in foundation seed potatoes in Japan,and screening for symptoms in Japanese potato cultivars

In 2008 and 2009 seasons, a sudden increase in Potato virus Y (PVY) incidence was recorded in foundation seed potatoes in Hokkaido, northern Japan. This increase was obvious during the field inspection and the postharvest indexing. Molecular typing revealed that besides the previously reported strains of PVY^O and PVY^NA‐N, the most common strain identified was the recombinant PVY^NTN, with three characteristic recombinant junctions at the HC‐Pro, VPg and CP regions. No potato tuber necrotic ringspot disease (PTNRD) was observed in foundation seed potatoes in correlation with the presence of PVY^NTN. Moreover, an isolate with a typical PVY^NTN recombinant genome, namely Eu‐12Jp, did not induce PTNRD in 62 Japanese potato cultivars tested in both primarily and secondarily infected plants. Two cultivars carrying the extreme resistance gene Ry_chc were resistant to the infection with Eu‐12Jp, which presents potential sources of resistance to PVY^NTN. Eu‐12Jp induced systemic mottle in potato cultivars Desiree and King Edward carrying resistance genes Ny and Nc, respectively, but induced a hypersensitive reaction in potato cultivar Maris Bard, with the Nz hypothetical resistance gene typical of the PVY^Z strain group. Therefore, based on the genome structure and the reaction of the potato N resistance genes, Eu‐12Jp should be classified as PVY^Z‐NTN, as described for isolates from Idaho, USA recently. This is the first report of PVY^Z‐NTN in Japan and the sudden and increased occurrence of PVY^NTN/PVY^Z‐NTN represents a potential risk of PTNRD developing and increases the significance of PVY in Japan.     

地高辛标记的cDNA探针检测烟草花叶病毒、黄瓜花叶病毒及马铃薯Y病毒

 根据已发表的烟草花叶病毒(Tobacco mosaic virus,TMV)、黄瓜花叶病毒(Cucumber mosaic virus,CMV)和马铃薯Y病毒(Potato virus Y,PVY)的外壳蛋白基因序列,设计特异引物,分别以提取的TMV、CMV和PVY侵染的病叶总RNA为模板,反转录PCR进行体外扩增,分别得到长度为0.44、0.77、0.80 kb的目的片段,并克隆到pGEM-T easy质粒载体上,以构建的重组质粒为模板,用PCR方法合成了相应的地高辛标记的双链DNA探针。以合成的探针通过斑点杂交技术检测烟草病叶总RNA和烟草病叶汁液。TMV、CMV和PVY的3种地高辛探针检测各自感染的烟草病叶总RNA的稀释低限分别为1:1000、1:10000、1:320,检测各自侵染烟草病汁液的最大稀释倍数分别为1:100、1:100、1:10,而每种探针与健康烟草和其它2种病毒的反应均为阴性。     

马铃薯Y病毒对不同马铃薯品种的致病力

为明确不同马铃薯Y病毒(PVY)株系对马铃薯的影响及危害,采用PVYN:O、PVYN-Wi、PVYNTN-NW(SYRⅠ)和PVYNTN-NW(SYRⅡ)株系分离物人工侵染马铃薯,并通过透射电子显微镜观察经PVY侵染后马铃薯植株细胞的超微结构。结果表明,敏感品种更适用于PVY病毒致病力鉴定,敏感品种‘克新13’和‘克新18’对PVY不同分离物的反应强烈,差异显著,而‘兴加2号’对4个PVY分离株均表现耐病,虽然细胞内均出现叶绿体变形、单层膜小囊泡和典型的风轮状内含体,但症状只表现为不同程度的花叶。同时,发现PVYN-Wi致病力较弱,侵染后,4个马铃薯品种均出现花叶症状,细胞内部产生多膜结构、风轮状内含体,引起敏感品种‘克新13’和‘克新18’细胞变形、叶绿体变形和髓鞘样结构;PVYNTN-NW致病力最强,感病的‘克新13’和‘克新18’植株受害症状明显加重,且植株早衰、细胞破坏严重,有些死亡较快的植株甚至未产生特征性内含体结构;PVYN:O致病力中等,植株受害症状和超微结构变化也介于PVYN-Wi和PVYNTN-NW之间。不同马铃薯品种对PVY病毒的感病程度有较大差异,‘兴加2号’为耐病品种。     

Late blight and virus host-plant resistances,crossing ability and glycoalkaloids in Nordic potato germplasm*

Old potato cultivars from the Nordic Genetic Resource Center (NordGen) and advanced breeding clones from the Swedish University of Agricultural Sciences (SLU) were evaluated for susceptibility to Potato Virus Y (PVY) and Potato Leafroll Virus (PLRV), foliar and tuber resistance to late blight – caused by Phytophthora infestans – as well as for glycoalkaloid content and crossing ability. Enzyme-Linked Immunosorbant Assay (ELISA) tests were used for PVY and PLRV screening during two years that were characterized by intensive virus incidence and severity in the field, while foliar and tuber resistances to late blight were assessed under artificial inoculation with an aggressive Swedish isolate of P. infestans. Hybrid seeds were obtained by crossing cultivars such as ‘Kiva’, ‘Sarpo Mira’, ‘Rosamunda’ and ‘Superb’ with SLU advanced breeding clones and a selected clone of Solanum tuberosum Group Andigena. Some cultivars (‘Hårek’, ‘Sarpo Mira’) and breeding clones (04-2662, 04-2085) with late blight resistance did not show virus infection. The α-solanin and α-chaconin contents of some of the old Nordic potato cultivars and breeding clones were similar to the known Dutch table cultivar ‘Bintje’ after 3 years of testing. This research allows identification of promising Nordic potato cultivars and SLU breeding clones for further use in developing germplasm aiming at organic and conventional farming systems.     

利用分子标记对辣椒抗马铃薯Y病毒的3个QTLs进行选择

为获得含有特定基因型的个体,深入研究辣椒抗马铃薯Y病毒（PVY）不同QTLs之间的关系,利用AFLP、SCAR和CAPS标记在辣椒材料‘Perennial’和‘Yolo Wonder’组成的BC₂和BC₁S₁分离世代对抗PVY的3个QTLs位点进行了选择。结果从BC₂群体中选出47个在主效QTL上含有抗性位点的单株,从中选出25个在LG9 PY2染色体上含有抗性位点的单株,最后选出11个在LG11 P10染色体上含有抗性位点的单株;从BC₁S₁群体中选出55个在LG9 PY2染色体上具有纯合抗性位点的单株,从中选出12个在主效QTL上纯合抗性位点的单株。经卡平方检测,实际分离比例同理论分离比例差异不显著。     

NtMAP70基因在烟草抗马铃薯Y病毒过程中的作用

为了探明微管结合蛋白70(MAP70)在抗马铃薯Y病毒(PVY)中的作用机制,克隆了烟草Nt MAP70基因的全长,并进行了生物信息学分析.利用实时荧光定量PCR研究了该基因在烟草不同时期和不同部位中的表达水平,结果表明,NtMAP70在烟草的各个生长期均有表达,且在根中的表达量最高.构建了基于双生病毒卫星诱导的烟草Nt MAP70的沉默载体,以中国番茄黄化曲叶病毒(TYLCCNV)为辅助病毒在烟草中沉默了该基因.与对照相比,在Nt MAP70基因沉默的烟草中PVY侵染速率明显减缓,病毒含量显著降低.     

采用多基因联合方法鉴定福建长乐和福清产区马铃薯Y病毒株系组成

【目的】马铃薯Y病毒(Potato virus Y,PVY)是马铃薯生产上危害较为严重的病毒,也是制约马铃薯可持续发展的主要病毒之一。论文旨在开发一套简便、准确、快速的PVY分子鉴定技术,并采用该技术及时查明福建省部分产区PVY病害的发生、分布及PVY株系组成。【方法】采用ELISA方法对采自福建省长乐市、福清市马铃薯种植区疑似受PVY感染的样品进行检测,并根据文献报道的PVY P1、VPg和CP基因保守区设计3对简并引物,对ELISA检测后的阳性样品进行基因扩增、克隆,并将获得的序列进行核苷酸序列一致性、重组位点、基因型分布和系统发育分析。【结果】ELISA检测结果表明,17份样品中有13个样品与PVY抗体呈阳性反应,其他呈阴性反应。13个阳性样品均能成功扩增出3个与P1、VPg和CP基因预期大小一致的特异片段。BLAST比对分析显示P1、VPg和CP基因与文献报道的已知PVY分离物的核苷酸序列一致性分别为72%—99%、85%—99%和88%—99%。P1、VPg和CP 3个基因联合序列分析显示,FQ01分离物与PVY~(N-Wi)株系的核苷酸序列一致性最高,FQ08分离物与PVYE株系的核苷酸序列一致性最高,CL01、CL02、CL05和CL13 4个分离物与PVY~(NTN-NW)株系SYR-I型的核苷酸序列一致性最高,CL03、CL04、FQ02、FQ06、FQ09、FQ11和CL12 7个分离物与PVY~(NTN-NW)株系SYR-II型的核苷酸序列一致性最高。重组分析显示,除CP基因外,长乐市和福清市两个产区的PVY分离物的P1和VPg基因中均检测到显著的重组信号。基因型统计分析结果显示,长乐产区的P1基因为N型(60%)和N×O重组型(40%),VPg基因均为N×O重组型,而CP基因均为O型,而福清产区的P1基因为N型(25%)和N×O重组型(75%),VPg基因为N×O重组型(87.5%)和O型(12.5%),而CP基因除了一个分离物为N型外,其他均为O型。系统发育分析显示分离物FQ01与PVYN-Wi株系聚为一簇,FQ08与PVYE株系聚为一簇,CL01、CL02、CL05和CL13与PVY~(NTN-NW)株系SYR-I型聚为一簇,CL03、CL04、FQ02、FQ06、FQ09、FQ11和CL12与PVY~(NTN-NW)株系SYR-II型聚为一簇,表明在系统发育关系上,分离物FQ01与PVYN-Wi株系最近,FQ08与PVYE株系最近,CL01、CL02、CL05和CL13与PVY~(NTN-NW)株系SYR-I型最近,CL03、CL04、FQ02、FQ06、FQ09、FQ11和CL12与PVY~(NTN-NW)株系SYR-II型最近。【结论】PVY在福建省长乐市、福清市马铃薯种植区普遍存在,重组株系已成为田间的主流株系,且PVY~(NTN-NW)已成为优势重组株系。