Disease and Stress Biology Department, John Innes Centre, Colney Lane, NR4 7UH, Norwich, UK.
Published: March 2008
AI Article Synopsis
Article Abstract
Powdery mildew fungi are parasites that cause disease on a wide range of important crops. Plant resistance (R) genes, which induce host defences against powdery mildews, encode proteins that recognise avirulence (AVR) molecules from the parasite in a gene-for-gene manner. To gain insight into how virulence evolves in Blumeria graminis f.sp. hordei, associations between segregating AVR genes were established. As a prerequisite to the isolation of AVR genes, two loci were selected for further analysis. AVR(a22) is located in a tightly linked cluster comprising AVR(a10) and AVR(k1) as well as up to five other AVR genes. The ratio between physical and genetic distance in the cluster ranged between 0.7 and 35 kB/cM. The AVR(a22) locus was delimited by the previously isolated gene AVR(a10) and two cleaved amplified polymorphic sequence (CAPS) markers, 19H12R and 74E9L. By contrast, AVR(a12) was not linked to other AVR genes in two crosses. Bulk segregant analysis of over 100,000 AFLP fragments yielded two markers, ETAMTG-285 and PAAMACT-473, mapping 10 and 2cM from AVR(a12), respectively, thus delimiting AVR(a12) on one side. All markers obtained for AVR(a12) mapped proximal to it, indicating that the gene is located at the end of a chromosome. Three more AVR(a10) paralogues were identified at the locus interspersed among genes for metabolic enzymes and abundant repetitive elements, especially those homologous to the CgT1 class of retrotransposons. The flanking and close markers obtained will facilitate the isolation of AVR(a22) and AVR(a12) and provide useful tools for studies of the evolution of powdery mildew fungi in agriculture and nature.
The avirulence (AVR) genes of Magnaporthe oryzae are pivotal in eliciting resistance responses in rice, which are mediated by resistance (R) genes in rice. Monitoring the variation of AVR genes in the pathogen is essential for strategically deploying R genes in rice cultivation regions. In this study, a total of 214 isolates were collected from Jiangxi Province, China, in 2022, and the distribution and variation of AVR genes in these isolates were analyzed by PCR amplification and sequencing.
is a significant phytopathogen causing downy mildew disease in cucurbit crops. Understanding the molecular mechanisms underlying the interaction between and its host is essential for developing effective disease management strategies. RxLR effectors, secreted by pathogens, play a crucial role in modulating host immunity.
Sunflower broomrape (Orobanche cumana) is a parasitic plant harming sunflower crops in Europe and Asia, with a new virulent population identified in Southern Spain that can overcome existing resistance in sunflower hybrids.
The study involved analyzing 144 families from a cross between different populations of O. cumana and showed a 1:3 ratio of avirulent to virulent plants, suggesting that the trait is controlled by a single gene, mapped to chromosome 2.
This research is the first to map an avirulence gene in a parasitic plant, confirming a gene-for-gene relationship between O. cumana and sunflowers and revealing how the presence of this gene affects the population structure of the parasite
A fundamental tenet of evolutionary genetics is that the direction and strength of selection on individual loci varies with the environment. Barcoded evolutionary lineage tracking is a powerful approach for high-throughput measurement of selection within experimental evolution that to date has largely been restricted to studies within microbial systems, largely because the random integration of barcodes within animals is limited by physical and molecular protection of the germline. Here, we use the recently developed TARDIS barcoding system in (Stevenson et al.
Intracellular nucleotide-binding domain and leucine-rich repeat-containing (NLR) receptors play crucial roles in immunity across multiple domains of life. In plants, a subset of NLRs contain noncanonical integrated domains that are thought to have evolved from host targets of pathogen effectors to serve as pathogen baits. However, the functions of host proteins with similarity to NLR integrated domains and the extent to which they are targeted by pathogen effectors remain largely unknown.
