Topic
Plant disease resistance
About: Plant disease resistance is a research topic. Over the lifetime, 12952 publications have been published within this topic receiving 381820 citations. The topic is also known as: plant innate immunity.
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TL;DR: The authors' data indicate that resistance in V. riparia is induced after infection, and is not based on differences in basal gene expression between the two species, and could be exploited in future biotechnological approaches to increase disease resistance in susceptible grapevine species.
Abstract: Downy mildew is a destructive grapevine disease caused by Plasmopara viticola (Berk. and Curt.) Berl. and de Toni, which can only be controlled by intensive fungicide treatments. Natural sources of resistance from wild grapevine (Vitis) species are used in conventional breeding approaches, but the signals and effectors involved in resistance in this important crop species are not well understood. Early transcriptional changes associated with P. viticola infection in susceptible V. vinifera and resistant V. riparia plants were analyzed using the Combimatrix microarray platform. Transcript levels were measured 12 and 24 h post-inoculation, reflecting the time points immediately preceding the onset of resistance in V. riparia, as determined by microscopic analysis. Our data indicate that resistance in V. riparia is induced after infection, and is not based on differences in basal gene expression between the two species. The strong and rapid transcriptional reprogramming involves the induction of pathogenesis-related proteins and enzymes required for the synthesis of phenylpropanoid-derived compounds, many of which are also induced, albeit to a lesser extent, in V. vinifera. More interestingly, resistance in V. riparia also involves the specific modulation of numerous transcripts encoding components of signal transduction cascades, hypersensitive reaction markers and genes involved in jasmonate biosynthesis. The limited transcriptional modulation in V. vinifera represents a weak attempted defense response rather than the activation of compatibility-specific pathways. Several candidate resistance genes were identified that could be exploited in future biotechnological approaches to increase disease resistance in susceptible grapevine species. Measurements of jasmonic acid and methyl jasmonate in infected leaves suggest that this hormone may also be involved in V. riparia resistance to P. viticola.
159 citations
TL;DR: It is found that tomato strain PstDC3000 expressing avrRpt2 grew to significantly higher levels and often resulted in the formation of more severe disease symptoms in ecotype No-0 plants carrying a mutant RPS2 allele, as well as in two Col-0 mutant lines, cpr5 rps2 and coil rPS2, that exhibit enhanced resistance.
Abstract: Several bacterial avr genes have been shown to contribute to virulence on susceptible plants lacking the corresponding resistance (R) gene. The mechanisms by which avr genes promote parasitism and disease, however, are not well understood. We investigated the role of the Pseudomonas syringae pv. tomato avrRpt2 gene in pathogenesis by studying the interaction of P. syringae pv. tomato strain PstDC3000 expressing avrRpt2 with several Arabidopsis thaliana lines lacking the corresponding R gene, RPS2. We found that PstDC3000 expressing avrRpt2 grew to significantly higher levels and often resulted in the formation of more severe disease symptoms in ecotype No-0 plants carrying a mutant RPS2 allele, as well as in two Col-0 mutant lines, cpr5 rps2 and coil rps2, that exhibit enhanced resistance. We also generated transgenic A. thaliana lines expressing avrRpt2 and demonstrated, by using several different assays, that expression of avrRpt2 within the plant also promotes virulence of PstDC3000. Thus, AvrRpt2 appears to promote pathogen virulence from within the plant cell.
159 citations
TL;DR: A novel effector target in the apoplast that contributes to immunity and is under diversifying selection, but only in the natural host of the pathogen.
Abstract: Since the leaf apoplast is a primary habitat for many plant pathogens, apoplastic proteins are potent, ancient targets for apoplastic effectors secreted by plant pathogens. So far, however, only a few apoplastic effector targets have been identified and characterized. Here, we discovered that the papain-like cysteine protease C14 is a new common target of EPIC1 and EPIC2B, two apoplastic, cystatin-like proteins secreted by the potato (Solanum tuberosum) late blight pathogen Phytophthora infestans. C14 is a secreted protease of tomato (Solanum lycopersicum) and potato typified by a carboxyl-terminal granulin domain. The EPIC-C14 interaction occurs at a wide pH range and is stronger than the previously described interactions of EPICs with tomato defense proteases PIP1 and RCR3. The selectivity of the EPICs is also different when compared with the AVR2 effector of the fungal tomato pathogen Cladosporium fulvum, which targets PIP1 and RCR3, and only at apoplastic pH. Importantly, silencing of C14 increased susceptibility to P. infestans, demonstrating that this protease plays a role in pathogen defense. Although C14 is under conservative selection in tomato, it is under diversifying selection in wild potato species (Solanum demissum, Solanum verrucosum, and Solanum stoliniferum) that are the natural hosts of P. infestans. These data reveal a novel effector target in the apoplast that contributes to immunity and is under diversifying selection, but only in the natural host of the pathogen.
158 citations
TL;DR: The research was conducted by testing 152 F 3 -derived lines from a cross between a partially resistant cultivar and a susceptible cultivar for resistance to sclerotinia stem rot and agronomic traits at two Michigan locations in each of 2 yr.
Abstract: Little is known about the inheritance of partial resistance in soybean [Glycine max (L.) Merr.] to sclerotinia stem rot, caused by the fungal pathogen Sclerotinia sclerotiorum (Lib.) de Bary. This information would be useful to soybean breeders who are developing cultivars with resistance to sclerotinia stem rot. Our objectives were to study the inheritance of partial resistance to sclerotinia stem rot and to present the initial results from mapping quantitative trait loci (QTL) that confer this resistance. The research was conducted by testing 152 F 3 -derived lines from a cross between a partially resistant cultivar, Novartis Seeds S19-90 (formerly Northrup King), and a susceptible cultivar, Williams 82, for resistance to sclerotinia stem rot and agronomic traits at two Michigan locations in each of 2 yr. These lines were also evaluated for 123 genetic markers to map resistance genes. The resistance of the lines, measured with a disease severity index (DSI), was normally distributed across environments. Significant (P < 0.05) genotypic variation, genotype × location, and genotype × year interactions were observed for DSI. The broad-sense heritability estimate for DSI across both locations and years was 0.59. More severe disease was significantly correlated with greater lodging, later date of maturity, later R1 date, and greater plant height. Three QTL, explaining 10, 9, and 8% of the variability for DSI across environments, were mapped with genetic markers. Two of these QTL were also significantly associated with disease escape mechanisms such as plant height, lodging, and date of flowering. The other QTL was not significantly associated with escape mechanisms and may map one or more genes involved in physiological resistance to the disease.
158 citations
TL;DR: Quantitative trait locus (QTL) analysis revealed two strong QTLs on linkage groups (LGs) 18 and 09, and the locus on LG 18 was found to be identical with the previously described locus Rpv3 and is transmitted by Gf.Ga-52-42.
Abstract: A population derived from a cross between grapevine breeding strain Gf.Ga-52-42 and cultivar ‘Solaris’ consisting of 265 F1-individuals was genetically mapped using SSR markers and screened for downy mildew resistance. Quantitative trait locus (QTL) analysis revealed two strong QTLs on linkage groups (LGs) 18 and 09. The locus on LG 18 was found to be identical with the previously described locus Rpv3 and is transmitted by Gf.Ga-52-42. ‘Solaris’ transmitted the resistance-related locus on LG 09 explaining up to 50% of the phenotypic variation in the population. This downy mildew resistance locus is named Rpv10 for resistance to Plasmopara viticola. Rpv10 was initially introgressed from Vitis amurensis, a wild species of the Asian Vitis gene pool. The one-LOD supported confidence interval of the QTL spans a section of 2.1 centi Morgan (cM) corresponding to 314 kb in the reference genome PN40024 (12x). Eight resistance gene analogues (RGAs) of the NBS–LRR type and additional resistance-linked genes are located in this region of PN40024. The F1 sub-population which contains the Rpv3 as well as the Rpv10 locus showed a significantly higher degree of resistance, indicating additive effects by pyramiding of resistance loci. Possibilities for using the resistance locus Rpv10 in a grapevine breeding programme are discussed. Furthermore, the marker data revealed ‘Severnyi’ × ‘Muscat Ottonel’ as the true parentage for the male parent of ‘Solaris’.
158 citations