Plant immune system incompatibility and the distribution of enemies in natural hybrid zones

Abstract Genetic analyses of reproductive barriers represent one of the few methods by which theories of speciation can be tested. However, genetic study is often restricted to model organisms that have short generation times and are easily propagated in the laboratory. Replicate hybrid zones with a diversity of recombinant genotypes of varying age offer increased resolution for genetic mapping experiments and expand the pool of organisms amenable to genetic study. Using 88 markers distributed across 17 chromosomes, we analyze the introgression of chromosomal segments of Helianthus petiolaris into H. annuus in three natural hybrid zones. Introgression was significantly reduced relative to neutral expectations for 26 chromosomal segments, suggesting that each segment contains one or more factors that contribute to isolation. Pollen sterility is significantly associated with 16 of these 26 segments, providing a straightforward explanation of why this subset of blocks is disadvantageous in hybrids. In addition, comparison of rates of introgression across colinear vs. rearranged chromosomes indicates that close to 50% of the barrier to introgression is due to chromosomal rearrangements. These results demonstrate the utility of hybrid zones for identifying factors contributing to isolation and verify the prediction of increased resolution relative to controlled crosses.

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Pivoting the Plant Immune System from Dissection to Deployment

Science ◽

10.1126/science.1236011 ◽

2013 ◽

Vol 341 (6147) ◽

pp. 746-751 ◽

Cited By ~ 571

Author(s):

Jeffery L. Dangl ◽

Diana M. Horvath ◽

Brian J. Staskawicz

Keyword(s):

Immune System ◽

Conceptual Understanding ◽

Germ Plasm ◽

Plant Diseases ◽

Sequencing Technology ◽

Plant Immune System ◽

Rich Diversity ◽

The World ◽

The Rich ◽

Molecular Components

Diverse and rapidly evolving pathogens cause plant diseases and epidemics that threaten crop yield and food security around the world. Research over the last 25 years has led to an increasingly clear conceptual understanding of the molecular components of the plant immune system. Combined with ever-cheaper DNA-sequencing technology and the rich diversity of germ plasm manipulated for over a century by plant breeders, we now have the means to begin development of durable (long-lasting) disease resistance beyond the limits imposed by conventional breeding and in a manner that will replace costly and unsustainable chemical controls.

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Antagonistic Control of Disease Resistance Protein Stability in the Plant Immune System

Science ◽

10.1126/science.1109977 ◽

2005 ◽

Vol 309 (5736) ◽

pp. 929-932 ◽

Cited By ~ 165

Author(s):

B. F. Holt

Keyword(s):

Disease Resistance ◽

Immune System ◽

Protein Stability ◽

Plant Immune System ◽

Disease Resistance Protein ◽

Resistance Protein ◽

Antagonistic Control

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Network organization of the plant immune system: from pathogen perception to robust defense induction

The Plant Journal ◽

10.1111/tpj.15462 ◽

2021 ◽

Author(s):

Florent Delplace ◽

Carine Huard‐Chauveau ◽

Richard Berthomé ◽

Dominique Roby

Keyword(s):

Immune System ◽

Network Organization ◽

Plant Immune System ◽

Defense Induction

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Molecular evolution of plant immune system genes

Trends in Genetics ◽

10.1016/j.tig.2006.09.011 ◽

2006 ◽

Vol 22 (12) ◽

pp. 662-670 ◽

Cited By ~ 91

Author(s):

P TIFFIN ◽

D MOELLER

Keyword(s):

Immune System ◽

Molecular Evolution ◽

Plant Immune System

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Plant immune system uses demethylation

Nature Reviews Genetics ◽

10.1038/nrg3441 ◽

2013 ◽

Vol 14 (3) ◽

pp. 155-155

Author(s):

Mary Muers

Keyword(s):

Immune System ◽

Plant Immune System

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Proteomics of the Honeydew from the Brown Planthopper and Green Rice Leafhopper Reveal They Are Rich in Proteins from Insects, Rice Plant and Bacteria

Insects ◽

10.3390/insects11090582 ◽

2020 ◽

Vol 11 (9) ◽

pp. 582

Author(s):

Jinghua Zhu ◽

Kunmiao Zhu ◽

Liang Li ◽

Zengxin Li ◽

Weiwei Qin ◽

...

Keyword(s):

Immune System ◽

Calcium Binding ◽

Rice Plant ◽

Brown Planthopper ◽

Waste Product ◽

Elongation Factor ◽

Nilaparvata Lugens ◽

Plant Responses ◽

Green Rice Leafhopper ◽

Plant Immune System

Honeydew is a watery fluid excreted by plant sap-feeding insects. It is a waste product for the insect hosts. However, it plays important roles for other organisms, such as serving as a nutritional source for beneficial insects and bacteria, as well as elicitors and effectors modulating plant responses. In this study, shotgun LC–MS/MS analyses were used to identify the proteins in the honeydew from two important rice hemipteran pests, the brown planthopper (Nilaparvata lugens, BPH) and green rice leafhopper (Nephotettix cincticeps, GRH). A total of 277 and 210 proteins annotated to insect proteins were identified in the BPH and GRH honeydews, respectively. These included saliva proteins that may have similar functions as the saliva proteins, such as calcium-binding proteins and apolipophorin, involved in rice plant defenses. Additionally, a total of 52 and 32 Oryza proteins were identified in the BPH and GRH honeydews, respectively, some of which are involved in the plant immune system, such as Pathogen-Related Protein 10, ascorbate peroxidase, thioredoxin and glutaredoxin. Coincidently, 570 and 494 bacteria proteins were identified from the BPH and GRH honeydews, respectively, which included several well-known proteins involved in the plant immune system: elongation factor Tu, flagellin, GroEL and cold-shock proteins. The results of our study indicate that the insect honeydew is a complex fluid cocktail that contains abundant proteins from insects, plants and microbes, which may be involved in the multitrophic interactions of plants–insects–microbes.

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Male territorial vocalizations and responses are decoupled in an avian hybrid zone

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2008.0046 ◽

2008 ◽

Vol 363 (1505) ◽

pp. 2879-2889 ◽

Cited By ~ 8

Author(s):

Paula M den Hartog ◽

Hans Slabbekoorn ◽

Carel ten Cate

Keyword(s):

Hybrid Zone ◽

Acoustic Signals ◽

Hybrid Zones ◽

Natural Hybrid ◽

Individual Male ◽

Individual Strategy ◽

Intraspecific Communication ◽

Selective Sensitivity ◽

Species Specific ◽

Male Signals

A core area of speciation research concerns the coevolution of species-specific signals and the selective sensitivity to such signals. Signals and responses to them should be tuned to each other, to be effective in intraspecific communication. Hybrid zones are ideal to study the presence of such ‘behavioural coupling’ and the mechanisms governing it, and this has rarely been done. Our study examines acoustic signals of males and their response to them in the context of territorial interactions in a natural hybrid zone between two dove species, Streptopelia vinacea and Streptopelia capicola . Male signals are important in hybrid zone dynamics as they are essential for territory establishment, which is crucial for successful reproduction. We tested whether the response of individual male hybrids is linked to how similar their own signal is to the playback signal. We did not find evidence for behavioural coupling. The combined evidence from the low level of response to hybrid and heterospecific signals outside the hybrid zone and a lack of coupling within the hybrid zone suggests that perceptual learning may explain our results. Learning to respond to locally abundant signals may be the best individual strategy and is likely to contribute to the maintenance of a hybrid zone.

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Structures of Phytophthora RXLR Effector Proteins

Journal of Biological Chemistry ◽

10.1074/jbc.m111.262303 ◽

2011 ◽

Vol 286 (41) ◽

pp. 35834-35842 ◽

Cited By ~ 109

Author(s):

Laurence S. Boutemy ◽

Stuart R. F. King ◽

Joe Win ◽

Richard K. Hughes ◽

Thomas A. Clarke ◽

...

Keyword(s):

Immune System ◽

Molecular Mechanisms ◽

Tandem Repeats ◽

Effector Proteins ◽

Functional Adaptation ◽

In Planta ◽

Effector Domains ◽

The Core ◽

Plant Immune System ◽

Molecular Stability

Phytopathogens deliver effector proteins inside host plant cells to promote infection. These proteins can also be sensed by the plant immune system, leading to restriction of pathogen growth. Effector genes can display signatures of positive selection and rapid evolution, presumably a consequence of their co-evolutionary arms race with plants. The molecular mechanisms underlying how effectors evolve to gain new virulence functions and/or evade the plant immune system are poorly understood. Here, we report the crystal structures of the effector domains from two oomycete RXLR proteins, Phytophthora capsici AVR3a11 and Phytophthora infestans PexRD2. Despite sharing <20% sequence identity in their effector domains, they display a conserved core α-helical fold. Bioinformatic analyses suggest that the core fold occurs in ∼44% of annotated Phytophthora RXLR effectors, both as a single domain and in tandem repeats of up to 11 units. Functionally important and polymorphic residues map to the surface of the structures, and PexRD2, but not AVR3a11, oligomerizes in planta. We conclude that the core α-helical fold enables functional adaptation of these fast evolving effectors through (i) insertion/deletions in loop regions between α-helices, (ii) extensions to the N and C termini, (iii) amino acid replacements in surface residues, (iv) tandem domain duplications, and (v) oligomerization. We hypothesize that the molecular stability provided by this core fold, combined with considerable potential for plasticity, underlies the evolution of effectors that maintain their virulence activities while evading recognition by the plant immune system.

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