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.

Resistance variation within and among host populations in a plant–pathogen metapopulation: implications for regional pathogen dynamics

Abstract: Summary 1 Studies conducted on natural host-pathogen metapopulations have revealed considerable diversity of host resistance phenotypes within populations. The resistance structure of non-infected populations has, however, been largely ignored and the role of among-population variation in resistance profiles in the dynamics of natural pathogen populations is poorly understood. 2 The Plantago lanceolata ‐ Podosphaera plantaginis pathosystem in the Aland Islands in south-west Finland is characterized by the highly fragmented distribution of the host. Only a small fraction of the host populations is infected at one point in time and pathogen turnover rate is high. I studied a sample of these populations to find out whether adjacent host populations are differentiated in their resistance structure and whether variable levels of disease resistance among host populations could be linked to disease incidence patterns. 3 Results show striking differences in the resistance structure both within and among host populations. Sixteen resistance phenotypes were identified in a sample of 64 host individuals. Populations varied from one in which all sampled individuals represented a different resistance phenotype, to one in which half showed identical resistance responses. 4 There was no association between local resistance composition and the geographical distance between populations, suggesting that within-population processes, such as founder effects and genetic drift, largely determine local resistance structure. 5 Non-infected populations showed significantly higher mean levels of resistance than infected populations, suggesting that differences in the mean level of resistance among host populations may retard the spread of the fungus and thereby decrease the probability of regional epidemics.

Overexpression of snakin-1 gene enhances resistance to Rhizoctonia solani and Erwinia carotovora in transgenic potato plants

Abstract: Snakin‐1 (SN1), a cysteine‐rich peptide with broad‐spectrum antimicrobial activity in vitro, was evaluated for its ability to confer resistance to pathogens in transgenic potatoes. Genetic variants of this gene were cloned from wild and cultivated Solanum species. Nucleotide sequences revealed highly evolutionary conservation with 91–98% identity values. Potato plants (S. tuberosum subsp. tuberosum cv. Kennebec) were transformed via Agrobacterium tumefaciens with a construct encoding the S. chacoense SN1 gene under the regulation of the ubiquitous CaMV 35S promoter. Transgenic lines were molecularly characterized and challenged with either Rhizoctonia solani or Erwinia carotovora to analyse whether constitutive in vivo overexpression of the SN1 gene may lead to disease resistance. Only transgenic lines that accumulated high levels of SN1 mRNA exhibited significant symptom reductions of R. solani infection such as stem cankers and damping‐off. Furthermore, these overexpressing lines showed significantly higher survival rates throughout the fungal resistance bioassays. In addition, the same lines showed significant protection against E. carotovora measured as: a reduction of lesion areas (from 46.5 to 88.1% with respect to the wild‐type), number of fallen leaves and thickened or necrotic stems. Enhanced resistance to these two important potato pathogens suggests in vivo antifungal and antibacterial activity of SN1 and thus its possible biotechnological application.

Agrobacterium-mediated transient gene expression and silencing: a rapid tool for functional gene assay in potato.

Abstract: Potato is the third most important food crop worldwide. However, genetic and genomic research of potato has lagged behind other major crops due to the autopolyploidy and highly heterozygous nature associated with the potato genome. Reliable and technically undemanding techniques are not available for functional gene assays in potato. Here we report the development of a transient gene expression and silencing system in potato. Gene expression or RNAi-based gene silencing constructs were delivered into potato leaf cells using Agrobacterium-mediated infiltration. Agroinfiltration of various gene constructs consistently resulted in potato cell transformation and spread of the transgenic cells around infiltration zones. The efficiency of agroinfiltration was affected by potato genotypes, concentration of Agrobacterium, and plant growth conditions. We demonstrated that the agroinfiltration-based transient gene expression can be used to detect potato proteins in sub-cellular compartments in living cells. We established a double agroinfiltration procedure that allows to test whether a specific gene is associated with potato late blight resistance pathway mediated by the resistance gene RB. This procedure provides a powerful approach for high throughput functional assay for a large number of candidate genes in potato late blight resistance.

Rice ESTs with disease-resistance gene- or defense-response gene-like sequences mapped to regions containing major resistance genes or QTLs.

Abstract: The chromosomal locations of 109 rice expressed sequence tags (ESTs) in the rice genome were determined using a doubled haploid mapping population. These ESTs show high similarity to disease resistance genes or to defense response genes. Nine of the ESTs were mapped to three regions that contain genetically defined resistance genes on chromosomes 6 and 11. Clustering of the ESTs in the rice genome was observed at several chromosomal regions. Some of the clusters were located in regions where quantitative trait loci (QTL) associated with partial resistance to rice blast, bacterial blight and sheath blight are known to lie. Three ESTs that were mapped to the regions containing blast resistance genes Pi2 and Pia were chosen for Northern analysis after inoculation of plants with the blast fungus. Two of them, which code for a receptor-like kinase and a putative membrane channel protein, respectively, and were mapped to the Pi2 locus, were induced by rice blast infection as early as 4 h after inoculation. Transcription of another EST, which codes for a homolog of a putative human tumor suppressor and was mapped to the region containing Pia, was repressed after blast infection. These findings demonstrate that the candidate-gene approach is an efficient way of mapping resistance genes or resistance QTLs in rice.