Publications by authors named "Diane G O Saunders"

Article Synopsis
  • Plant fungal parasites, like Puccinia striiformis, manipulate the host's metabolic pathways, particularly the glyoxylate cycle, to enhance their survival during infection.
  • In bread wheat, the gene encoding the enzyme isocitrate lyase (TaICL) is expressed differently in susceptible versus resistant interactions with the pathogen, with the TaICL-B version upregulated in successful infections.
  • Disrupting the TaICL-B gene leads to stronger resistance against Pst, as the mutant accumulates more organic acids that inhibit fungal growth, suggesting that targeting TaICL in breeding could improve wheat resistance to fungal diseases.
View Article and Find Full Text PDF

Ten years ago, (black) stem rust - the most damaging of wheat (Triticum aestivum) rusts - re-emerged in western Europe. Disease incidences have since increased in scale and frequency. Here, we investigated the likely underlying causes and used those to propose urgently needed mitigating actions.

View Article and Find Full Text PDF
Article Synopsis
  • * Research indicates that the ongoing wheat blast outbreak can be managed using the Rmg8 disease resistance gene and certain fungicides, but the fungus may develop resistance over time.
  • * There is an urgent need for genomic tracking of the wheat blast fungus and proactive breeding strategies to develop resistant wheat varieties and prevent further spread.
View Article and Find Full Text PDF

Since emerging in Brazil in 1985, wheat blast has spread throughout South America and recently appeared in Bangladesh and Zambia. Here we show that two wheat resistance genes, Rwt3 and Rwt4, acting as host-specificity barriers against non-Triticum blast pathotypes encode a nucleotide-binding leucine-rich repeat immune receptor and a tandem kinase, respectively. Molecular isolation of these genes will enable study of the molecular interaction between pathogen effector and host resistance genes.

View Article and Find Full Text PDF

Plant pathogens deliver effector proteins to reprogramme a host plants circuitry, supporting their own growth and development, whilst thwarting defence responses. A subset of these effectors are termed avirulence factors (Avr) and can be recognised by corresponding host resistance (R) proteins, creating a strong evolutionary pressure on pathogen Avr effectors that favours their modification/deletion to evade the immune response. Hence, identifying Avr effectors and tracking their allele frequencies in a population is critical for understanding the loss of host recognition.

View Article and Find Full Text PDF

Functional characterization of effector proteins of fungal obligate biotrophic pathogens, especially confirmation of avirulence (Avr) properties, has been notoriously difficult, due to the experimental intractability of many of these organisms. Previous studies in wheat have shown promising data suggesting the type III secretion system (T3SS) of bacteria may be a suitable surrogate for delivery and detection of Avr properties of fungal effectors. However, these delivery systems were tested in the absence of confirmed Avr effectors.

View Article and Find Full Text PDF

Targeting host processes that allow pathogens to thrive can be invaluable in resistance breeding. Here, we generated a deep-sequencing transcriptome time course for Puccinia striiformis f. sp.

View Article and Find Full Text PDF

Wheat stem rust, caused by the fungus f. sp. (Pgt), occurs in most wheat-growing areas worldwide, and, in western Europe since 2013, has started to re-emerge after many decades of absence.

View Article and Find Full Text PDF

Fungi have evolved an array of spore discharge and dispersal processes. Here, we developed a theoretical model that explains the ejection mechanics of aeciospore liberation in the stem rust pathogen Puccinia graminis. Aeciospores are released from cluster cups formed on its Berberis host, spreading early-season inoculum into neighboring small-grain crops.

View Article and Find Full Text PDF

Background: Transcriptomics is being increasingly applied to generate new insight into the interactions between plants and their pathogens. For the wheat yellow (stripe) rust pathogen (Puccinia striiformis f. sp.

View Article and Find Full Text PDF

is an obligate biotrophic fungal pathogen that causes orange rust of sugarcane, which is prevalent in many countries around the globe. In the United States, orange rust was first detected in sugarcane in Florida in 2007 and poses a persistent and economically damaging threat to the sugarcane industry in this region. Here, we generated the first genome assemblies for two isolates of (1040 and 2143) collected in Florida in 2017 from two sugarcane cultivars, CL85-1040 and CP89-2143, respectively.

View Article and Find Full Text PDF

Plant pathogens suppress defense responses to evade recognition and promote successful colonization. Although identifying the genes essential for pathogen ingress has traditionally relied on screening mutant populations, the post-genomic era provides an opportunity to develop novel approaches that accelerate identification. Here, RNA-seq analysis of 68 pathogen-infected bread wheat (Triticum aestivum) varieties, including three (Oakley, Solstice and Santiago) with variable levels of susceptibility, uncovered a branched-chain amino acid aminotransferase (termed TaBCAT1) as a positive regulator of wheat rust susceptibility.

View Article and Find Full Text PDF

Pathogen populations are expected to evolve virulence traits in response to resistance deployed in agricultural settings. However, few temporal datasets have been available to characterize this process at the population level. Here, we examined two temporally separated populations of Puccinia coronata f.

View Article and Find Full Text PDF

The plant apoplast is a harsh environment in which hydrolytic enzymes, especially proteases, accumulate during pathogen infection. However, the defense functions of most apoplastic proteases remain largely elusive. We show here that a newly identified small cysteine-rich secreted protein PC2 from the potato late blight pathogen Phytophthora infestans induces immunity in Solanum plants only after cleavage by plant apoplastic subtilisin-like proteases, such as tomato P69B.

View Article and Find Full Text PDF

Wheat stem rust caused by the fungus f. sp. (), is regaining prominence due to the recent emergence of virulent isolates and epidemics in Africa, Europe and Central Asia.

View Article and Find Full Text PDF

Background: Effective disease management depends on timely and accurate diagnosis to guide control measures. The capacity to distinguish between individuals in a pathogen population with specific properties such as fungicide resistance, toxin production and virulence profiles is often essential to inform disease management approaches. The genomics revolution has led to technologies that can rapidly produce high-resolution genotypic information to define individual variants of a pathogen species.

View Article and Find Full Text PDF

In recent years, the number of emergent plant pathogens (EPPs) has grown substantially, threatening agroecosystem stability and native biodiversity. Contributing factors include, among others, shifts in biogeography, with EPP spread facilitated by the global unification of monocultures in modern agriculture, high volumes of trade in plants and plant products and an increase in sexual recombination within pathogen populations. The unpredictable nature of EPPs as they move into new territories is a situation that has led to sudden and widespread epidemics.

View Article and Find Full Text PDF

In our recent article, we reported the first occurrence of wheat stem rust in the UK in nearly six decades. An increased incidence of wheat stem rust in Western Europe, caused by the fungus f. sp.

View Article and Find Full Text PDF

Physiological races of the oomycete Albugo candida are biotrophic pathogens of diverse plant species, primarily the Brassicaceae, and cause infections that suppress host immunity to other pathogens. However, A. candida race diversity and the consequences of host immunosuppression are poorly understood in the field.

View Article and Find Full Text PDF

Wheat stem rust, a devastating disease of wheat and barley caused by the fungal pathogen f. sp. , was largely eradicated in Western Europe during the mid-to-late twentieth century.

View Article and Find Full Text PDF

Accelerating international trade and climate change make pathogen spread an increasing concern. Hymenoscyphus fraxineus, the causal agent of ash dieback, is a fungal pathogen that has been moving across continents and hosts from Asian to European ash. Most European common ash trees (Fraxinus excelsior) are highly susceptible to H.

View Article and Find Full Text PDF