scholarly journals How do pathogens evolve novel virulence activities?

2021 ◽  
Author(s):  
Soledad Sacristan ◽  
Erica Goss ◽  
Sebastian Eves-Van den Akker
Keyword(s):  
De Novo ◽  
Driving Forces ◽  
Major Gene ◽  
Crop Protection ◽  
Pathogen Evolution ◽  
Pathogen Virulence ◽  
Major Gene Resistance ◽  
Pathogen Fitness ◽  
Microbe Interactions ◽  
Element Activity

We consider the state of knowledge on pathogen evolution of novel virulence activities, broadly defined as anything that increases pathogen fitness with the consequence of causing disease in either the qualitative or quantitative senses, including adaptation of pathogens to host immunity and physiology, host species, genotypes, or tissues, or the environment. The evolution of novel virulence activities as an adaptive trait is based on the selection exerted by hosts on variants that have been generated de novo or arrived from elsewhere. In addition, the biotic and abiotic environment a pathogen experiences beyond the host may influence pathogen virulence activities. We consider pathogen evolution in the context of host-pathogen evolution, host range expansion, and external factors that can mediate pathogen evolution. We then discuss the mechanisms by which pathogens generate and recombine the genetic variation that leads to novel virulence activities, including DNA point mutation, transposable element activity, gene duplication and neofunctionalization, and genetic exchange. In summary, if there is an (epi)genetic mechanism that can create variation in the genome, it will be used by pathogens to evolve virulence factors. Our knowledge of virulence evolution has been biased by pathogen evolution in response to major gene resistance, leaving other virulence activities underexplored. Understanding the key driving forces that give rise to novel virulence activities, and the integration of evolutionary concepts and methods with mechanistic research on plant–microbe interactions, can help inform crop protection.

Harnessing chemical ecology for environment-friendly crop protection

2021 ◽  
Author(s):  
Seogchan Kang ◽  
Rhea Lumactud ◽  
Ningxiao Li ◽  
Terrence H Bell ◽  
HyeSeon Kim ◽  
...  
Keyword(s):  
Disease Control ◽  
Large Scale ◽  
Crop Protection ◽  
Bioactive Metabolites ◽  
Small Scale ◽  
Environment Friendly ◽  
Protection Strategies ◽  
Health Related ◽  
Microbe Interactions ◽  
Synthetic Pesticides

Heavy reliance on synthetic pesticides for crop protection becomes increasingly unsustainable, calling for robust alternative strategies that do not degrade the environment and vital ecosystem services. There exist numerous reports of successful disease control using various microbes in small-scale trials. However, their inconsistent efficacy has hampered large-scale applications. An enhanced understanding of how beneficial microbes interact with plants, other microbes, and the environment and which factors affect their efficacy of disease control is crucial to deploy microbial allies as effective and reliable pesticide alternatives. Diverse metabolites produced by plants and microbes participate in pathogenesis and defense, regulate the growth and development of themselves and neighboring organisms, help maintain cellular homeostasis under varied environmental conditions, and affect the assembly and activity of plant and soil microbiomes. However, research on the metabolites associated with plant growth/health-related processes, except antibiotics, has not received adequate attention. This review highlights several classes of metabolites known or suspected to affect plant health, focusing on those associated with biocontrol and belowground plant-microbe and microbe-microbe interactions. The review also presents how new insights anticipated from systematically exploring the diversity and mechanism of action of bioactive metabolites can be harnessed to develop novel crop protection strategies.

scholarly journals Root Rot of Juniperus and Microbiota by Phytophthora lateralis in Oregon Horticultural Nurseries

Plant Disease ◽  
2020 ◽  
Vol 104 (5) ◽  
pp. 1500-1506
Author(s):  
Ebba K. Peterson ◽  
Franziska Rupp ◽  
Joyce Eberhart ◽  
Jennifer L. Parke
Keyword(s):  
Root Rot ◽  
Internal Transcribed Spacer ◽  
Major Gene ◽  
Resistance Breeding ◽  
Its2 Region ◽  
Phytophthora Spp ◽  
Major Gene Resistance ◽  
Phytophthora Lateralis ◽  
Chamaecyparis Lawsoniana ◽  
Port Orford Cedar

Widespread symptoms of root rot and mortality on Juniperus communis and Microbiota decussata were observed in two horticultural nurseries in Oregon, leading to the isolation of a Phytophthora sp. from diseased roots. Based on morphology and sequencing the internal transcribed spacer ITS1-5.8S-ITS2 region, isolates were identified as the invasive pathogen Phytophthora lateralis, causal agent of Port-Orford-cedar (POC; Chamaecyparis lawsoniana) root disease. Additional sequencing of the cytochrome c oxidase subunit 1 and 2 genes identified all isolates as belonging to the PNW lineage. Utilizing recovered isolates plus a POC-wildlands isolate and susceptible POC as controls, we completed Koch’s postulates on potted Juniperus and Microbiota plants. Nursery isolates were more aggressive than the forest isolate, which was used in the POC resistance breeding program. Increased aggressiveness was confirmed using a branch stem dip assay with four POC clones that differed in resistance, although no isolate completely overcame major-gene resistance. Isolates were sensitive to mefenoxam, a fungicide commonly used to suppress Phytophthora spp. growth in commercial nurseries. Although POC resistance is durable against these more aggressive nursery isolates, the expanded host range of P. lateralis challenges POC conservation through the continued movement of P. lateralis by the nursery industry.

scholarly journals Sequencing and De Novo Assembly of the Complete Chloroplast Genome of the Peruvian Carrot (Arracacia xanthorrhiza Bancroft)

2017 ◽  
Vol 5 (7) ◽  
Author(s):  
Javier Santiago Alvarado ◽  
Diane Hinojosa López ◽  
Isaury Maldonado Torres ◽  
María Margarita Meléndez ◽  
Rosalinda Aybar Batista ◽  
...  
Keyword(s):  
Puerto Rico ◽  
South America ◽  
Chloroplast Genome ◽  
De Novo ◽  
Crop Protection ◽  
Food Crop ◽  
Storage Roots ◽  
Complete Chloroplast Genome ◽  
Improvement Strategies ◽  
Chloroplast Genome Sequence

ABSTRACT Arracacia xanthorrhiza is an important secondary food crop in South America and Puerto Rico. The lack of crop protection and improvement strategies leads to infections damaging the storage roots. Here, we report the annotated complete chloroplast genome sequence of A. xanthorrhiza as a step toward developing genomic resources for this crop.

scholarly journals Inhibition of Resistance Gene-Mediated Defense in Rice by Xanthomonas oryzae pv. oryzicola

2006 ◽  
Vol 19 (3) ◽  
pp. 240-249 ◽  
Author(s):  
Seiko Makino ◽  
Akiko Sugio ◽  
Frank White ◽  
Adam J. Bogdanove
Keyword(s):  
Bacterial Blight ◽  
Major Gene ◽  
Rice Cultivar ◽  
Hypersensitive Reaction ◽  
Xanthomonas Oryzae ◽  
R Gene ◽  
R Genes ◽  
Apparent Lack ◽  
Type Iii ◽  
Major Gene Resistance

Xanthomonas oryzae pv. oryzae and the closely related X. oryzae pv. oryzicola cause bacterial blight and bacterial leaf streak of rice, respectively. Although many rice resistance (R) genes and some corresponding avirulence (avr) genes have been characterized for bacterial blight, no endogenous avr/R gene interactions have been identified for leaf streak. Genes avrXa7 and avrXa10 from X. oryzae pv. oryzae failed to elicit the plant defense-associated hypersensitive reaction (HR) and failed to prevent development of leaf streak in rice cultivars with the corresponding R genes after introduction into X. oryzae pv. oryzicola despite the ability of this pathovar to deliver an AvrXa10:Cya fusion protein into rice cells. Furthermore, coinoculation of X. oryzae pv. oryzicola inhibited the HR of rice cultivar IRBB10 to X. oryzae pv. oryzae carrying avrXa10. Inhibition was quantitative and dependent on the type III secretion system of X. oryzae pv. oryzicola. The results suggest that one or more X. oryzae pv. oryzicola type III effectors interfere with avr/R gene-mediated recognition or signaling and subsequent defense response in the host. Inhibition of R gene-mediated defense by X. oryzae pv. oryzicola may explain, in part, the apparent lack of major gene resistance to leaf streak.

scholarly journals Genetic resistance to white pine blister rust in limber pine (Pinus flexilis): major gene resistance in a northern population

2016 ◽  
Vol 46 (9) ◽  
pp. 1173-1178 ◽  
Author(s):  
Richard A. Sniezko ◽  
Robert Danchok ◽  
Douglas P. Savin ◽  
Jun-Jun Liu ◽  
Angelia Kegley
Keyword(s):  
Major Gene ◽  
Genetic Resistance ◽  
The United States ◽  
White Pine Blister Rust ◽  
White Pine ◽  
Pinus Flexilis ◽  
Limber Pine ◽  
Blister Rust ◽  
Major Gene Resistance ◽  
The Status

Limber pine, Pinus flexilis E. James, a wide-ranging tree species in western North America, is highly susceptible to white pine blister rust (WPBR), caused by the non-native fungal pathogen Cronartium ribicola J.C. Fisch. The Canadian populations in particular have been heavily impacted, and in 2014, limber pine was designated endangered in Canada by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC). Little is known about genetic resistance to WPBR in limber pine, but major gene resistance (MGR) has been characterized in some populations in the United States. This study examines resistance in seedling families from 13 parent trees from British Columbia, Alberta, and Oregon, representing the northern- and northwestern-most populations. Most families were susceptible, with 100% of the seedlings cankered, but one family from Alberta segregated 1:1 for cankered and canker free. This is the first report of (a) MGR in Canada of any of the four species of five-needle pines native to Canada and (b) any resistance in limber pine in Canadian populations and is the northernmost known incidence of putative R-gene resistance in a natural stand of any five-needle pine species. Many of the Canadian selections were from stands with high incidence of WPBR infection, and their high susceptibility in this trial suggests that further infection and mortality is likely in the Canadian populations.

scholarly journals Pyramiding Quantitative Resistance with a Major Resistance Gene in Apple: From Ephemeral to Enduring Effectiveness in Controlling Scab

Plant Disease ◽  
2018 ◽  
Vol 102 (11) ◽  
pp. 2220-2223 ◽  
Author(s):  
Pauline Lasserre-Zuber ◽  
Valérie Caffier ◽  
René Stievenard ◽  
Arnaud Lemarquand ◽  
Bruno Le Cam ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Plant Disease ◽  
Quantitative Resistance ◽  
Major Gene ◽  
Genetic Resistance ◽  
Control Plant ◽  
Resistance Factors ◽  
Major Gene Resistance ◽  
Major Resistance Gene ◽  
Over Time

Genetic resistance is a useful strategy to control plant disease, but its effectiveness may be reduced over time due to the emergence of pathogens able to circumvent the defenses of the plant. However, the pyramiding of different resistance factors in the same plant can improve the effectiveness and durability of the resistance. To investigate the potential for this approach in apple to control scab disease we surveyed scab incidence in two experimental orchards located at a distance of more than 300 km planted with apple genotypes carrying quantitative resistance and major gene resistance alone or in combination. Our results showed that the effectiveness of pyramiding in controlling scab was dependent on the site and could not be completely explained by the effectiveness level of the resistances alone.

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