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Virus Resistance (virus + resistance)
Selected AbstractsVirus Resistance in Cereals: Sources of Resistance, Genetics and BreedingJOURNAL OF PHYTOPATHOLOGY, Issue 9 2009Frank Ordon Abstract In cereals, soil-borne viruses transmitted by the plasmodiophorid Polymyxa graminis (e.g., Barley mild mosaic virus, Barley yellow mosaic virus or Soil-borne cereal mosaic virus), have increased in importance due to the increase of the acreage infested and because yield losses cannot be prevented by chemical measures. Due to global warming, it is also expected that insect transmitted viruses vectored by aphids (e.g., Barley yellow dwarf virus, Cereal yellow dwarf virus), leafhoppers (Wheat dwarf virus) or mites (e.g., Wheat streak mosaic virus), will become much more important even in cooler regions. The environmentally most sound and also most cost effective approach to prevent high yield losses caused by these viruses is breeding for resistance. Therefore, in contrast to other reviews on cereal viruses, this study briefly reviews present knowledge on cereal-infecting viruses and emphasizes especially the sources of resistance or tolerance to these viruses and their use in molecular breeding schemes. [source] Transgenic virus resistance in cultivated squash affects pollinator behaviourJOURNAL OF APPLIED ECOLOGY, Issue 5 2009Holly R. Prendeville Summary 1.,Two ecological risks associated with the use of transgenic crops are transgene movement into wild populations and effects on non-target organisms, such as pollinators. Despite the importance of pollinators, and their contribution to the global food supply, little is known about how they are affected by transgenic crops. Pollinator preferences affect plant mating patterns; thus understanding the effects of transgenic crops on pollinators will aid in understanding transgene movement. 2.,Honey bee and squash bee visit number and duration were recorded on conventional and transgenic virus-resistant squash Cucurbita pepo planted in a randomized block design. Floral characters were measured to explain differences in pollinator behaviour. The effect of Zucchini Yellow Mosaic Virus infection on pollinator behaviour was also examined. 3.,Honey bees visited female conventional flowers more than female transgenic flowers. Conventional flowers were generally larger with more nectar than transgenic flowers, although floral traits did not account for differences in pollinator visitation. 4.,Squash bees visited male transgenic flowers more than male conventional flowers; squash bees also spent more time in female transgenic flowers than in female conventional flowers. Transgenic flowers were significantly larger with greater amounts of sweeter nectar and they were present in greater number. Floral traits accounted for some of the variation in pollinator visitation. 5.,Squash bee visit number and duration did not differ between virus-infected and healthy plants, but this may be because pollinator behaviour was observed early in the virus infection. 6.,Synthesis and applications. Pollinator behaviour controls patterns of plant mating thus non-target effects of transgenic resistance, such as those observed here, may influence transgene movement into wild populations. These results suggest that transgenic crops should not be planted within the native range of wild relatives because pleiotropic effects may affect crop-wild hybridization and transgene introgression into wild populations. [source] Regulation of Eukaryotic Initiation Factor 4E and Its Isoform: Implications for Antiviral Strategy in PlantsJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 10 2006Yu-Yang Zhang Abstract In recent years, biotechnology has permitted regulation of the expression of endogenous plant genes to improve agronomically important traits. Genetic modification of crops has benefited from emerging knowledge of new genes, especially genes that exhibit novel functions, one of which is eukaryotic initiation factor 4E (eIF4E). eIF4E is one of the most important translation initiation factors involved in eukaryotic initiation. Recent research has demonstrated that virus resistance mediated by eIF4E and its isoform eIF (iso)4E occurs in several plant-virus interactions, thus indicating a potential new role for eIF4E/eIF(iso)4E in resistance strategies against plant viruses. In this review, we briefly describe eIF4E activity in plant translation, its potential role, and functions of the eIF4E subfamily in plant-virus interactions. Other initiation factors such as eIF4G could also play a role in plant resistance against viruses. Finally, the potential for developing eIF4E-mediated resistance to plant viruses in the future is discussed. Future research should focus on elucidation of the resistance mechanism and spectrum mediated by eIF4E. Knowledge of a particular plant-virus interaction will help to deepen our understanding of eIF4E and other eukaryotic initiation factors, and their involvement in virus disease control. (Managing editor: Li-Hui Zhao) [source] Hypersensitivity of Plum Genotypes to Plum Pox VirusJOURNAL OF PHYTOPATHOLOGY, Issue 3-4 2001Kegler The hypersensitive response (HR) of plum hybrid K4 as an active defence mechanism is directed against certain plum pox virus (PPV) strains/isolates of the type CG but not against type DI. There is no clear correlation between the HR of K4 and serological differences of the PPV strains D, M and C, respectively. A total of 14 genotypes out of 21 progenies of K4 reacted necrotically and were proved to be either hypersensitive and field resistant or highly sensitive and not field resistant. The HR can be connected with a complete or with an incomplete virus localization in K4 and some of its progenies. The remaining genotypes were more or less sensitive and tolerant, respectively. Growth of buds from PPV-CG-infected plum cultivars on K4 differed in the degree of systemic virus invasion in the plant as a trait of quantitative virus resistance. The percentage of growing buds correlated with the level of quantitative PPV resistance. [source] Unravelling the genetic diversity of the three main viruses involved in Sweet Potato Virus Disease (SPVD), and its practical implicationsMOLECULAR PLANT PATHOLOGY, Issue 2 2005FRED TAIRO SUMMARY Sweetpotato (Ipomoea batatas) is a widely grown food crop, in which the most important diseases are caused by viruses. Genetic variability of three widely distributed sweetpotato viruses was analysed using data from 46 isolates of Sweet potato feathery mottle virus (SPFMV), 16 isolates of Sweet potato mild mottle virus (SPMMV) and 25 isolates of Sweet potato chlorotic stunt virus (SPCSV), of which 19, seven and six isolates, respectively, are newly characterized. Division of SPFMV into four genetic groups (strains) according to phylogenetic analysis of coat protein (CP) encoding sequences revealed that strain EA contained the East African isolates of SPFMV but none from elsewhere. In contrast, strain RC contained ten isolates from Australia, Africa, Asia and North America. Strain O contained six heterogeneous isolates from Africa, Asia and South America. The seven strain C isolates from Australia, Africa, Asia, and North and South America formed a group that was genetically distant from the other SPFMV strains. SPMMV isolates showed a high level of variability with no discrete strain groupings. SPCSV isolates from East Africa were phylogenetically distant to SPCSV isolates from elsewhere. Only from East Africa were adequate data available for different isolates of the three viruses to estimate the genetic variability of their local populations. The implications of the current sequence information and the need for more such information from most sweetpotato-growing regions of the world are discussed in relation to virus diagnostics and breeding for virus resistance. [source] Citrus tristeza virus resistance in a core collection of sour orange based on a diversity study of three germplasm collections using QTL-linked markersPLANT BREEDING, Issue 4 2008G. P. Bernet Abstract Seven markers linked to QTL involved in CTV accumulation, leafminer resistance and apomictic reproduction were used to characterize 64 sour orange (Citrus aurantium L.) accessions from three national collections in order to identify a representative core in which the resistance behaviour against two Citrus tristeza virus (CTV) isolates was studied. Different degrees of apomixis were found between the foreign collections. Most of the C. aurantium accessions fall into three main groups based on three multilocus genotypes. The haplotype diversity at three CTV accumulation QTL-linked markers was further studied by sequence analysis of alleles. Genotypic and allelic diversity at one of them, tightly linked to Ctv-R2 in Poncirus trifoliata (L.) Raf., match the plant,CTV interaction types reported among Poncirus and Citrus species. Only those selected accessions from the major group presented CTV resistance during 30 months of continuous growth, but later the resistance broke down in some plants. CTV tolerance appears related to slow growing genotypes. Certain micronutrients: Mn, and B depending on the accession, might play a relevant role in this host,pathogen interaction particularly in alkaline soils. [source] Factors underpinning the responsiveness and higher levels of virus resistance realised in potato genotypes carrying virus-specific R genesANNALS OF APPLIED BIOLOGY, Issue 2 2010A.L. Vuorinen Responses to Potato virus A (PVA, genus Potyvirus) segregate to three phenotypic groups in a diploid cross between Solanum tuberosum subsp. andigena and a highly interspecific potato hybrid. The aim of this study was to compare gene expression between the progeny genotypes which react with hypersensitive response (HR) to PVA, allow PVA accumulation in inoculated leaves but restrict PVA infection to the inoculated leaf by blocking systemic movement [non-necrotic resistance (nnr)], or are susceptible (S) and systemically infected with PVA. Expression levels of ca 10 000 genes were compared using probes arranged in a microarray format, and real-time RT-PCR was applied for quantitative comparison of the expression of selected defense-related genes (DRGs). Results showed that a few DRGs were autoactivated in HR genotypes at an early stage of plant growth in the absence of PVA infection, which was not observed in the two other phenotypic groups (nnr and S). More detailed studies on the DRGs encoding a beta-1,3-glucanase, a chitinase and a basic PR-1b protein showed that autoactivation of the genes was not evident in vitro and up to 2 weeks of growth in soil in a controlled growth cabinet but was apparent 2 weeks later. Hence, autoinduction of these DRGs in the HR genotypes could be associated with growth stage, environmental factors or both. Furthermore, a number of other DRGs were induced in the inoculated leaves of HR genotypes as a response to infection with PVA, which was not observed in nnr and S genotypes. These results provide some novel information about factors underpinning the higher levels of virus resistance realised in potato genotypes carrying virus-specific R genes and suggest that part of the resistance is attributable to additional ,minor' genes functioning simultaneously, hence adding to the overall responsiveness and level of resistance against infection. These results also imply that some genotypes might be more responsive to chemical induction of pathogen and pest resistance, which could be considered in screening of progenies in plant-breeding programs. [source] | ||||||||||