Abstract
The Hessian fly (HF, Mayetiola destructor) is a plant-galling parasite of wheat (Triticum spp.). Seven percent of its genome is composed of highly diversified signal-peptide-encoding genes that are transcribed in HF larval salivary glands. These observations suggest that they encode effector proteins that are injected into wheat cells to suppress basal wheat immunity and redirect wheat development towards gall formation. Genetic mapping has determined that mutations in four of these genes are associated with HF larval survival (virulence) on plants carrying four different resistance (R) genes. Here, this line of investigation was pursued further using bulked-segregant analysis combined with whole genome resequencing (BSA-seq). Virulence to wheat R genes H6, Hdic, and H5 was examined. Mutations associated with H6 virulence had been mapped previously. Therefore, we used H6 to test the capacity of BSA-seq to map virulence using a field-derived HF population. This was the first time a non-structured HF population had been used to map HF virulence. Hdic virulence had not been mapped previously. Using a structured laboratory population, BSA-seq associated Hdic virulence with mutations in two candidate effector-encoding genes. Using a laboratory population, H5 virulence was previously positioned in a region spanning the centromere of HF autosome 2. BSA-seq resolved H5 virulence to a 1.3 Mb fragment on the same chromosome but failed to identify candidate mutations. Map-based candidate effectors were then delivered to Nicotiana plant cells via the type III secretion system of Burkholderia glumae bacteria. These experiments demonstrated that the genes associated with virulence to wheat R genes H6 and H13 are capable of suppressing plant immunity. Results are consistent with the hypothesis that effector proteins underlie the ability of HFs to survive on wheat.
Highlights
The Hessian fly (HF, Mayetiola destructor) is an economically important, gall-forming, insect pest
We decided to test the capacity of bulked-segregant analysis combined with whole genome resequencing (BSA-seq) in the HF using H6 virulence
Fisher’s exact test (FET) was performed and average -Log10(FET) values within sliding 10-kb genome windows were plotted as a smoothed line across the HF genome (Figure 2A)
Summary
The Hessian fly (HF, Mayetiola destructor) is an economically important, gall-forming, insect pest It has a gene-for-gene relationship with its host plant, wheat (Triticum spp.). Recent investigations involving HF Resistance (R) genes H13 and H9 in wheat illustrate this relationship (Stuart, 2015): H13 normally prevents HF larvae from galling wheat. “H13-virulent” HF larvae overcome this resistance; they both survive and gall H13plants This ability to survive and gall (H13 virulence) is conditioned by recessive null mutations in a single HF gene, called Avirulence (Avr) gene vH13 (Aggarwal et al, 2014). The gene-for-gene hypothesis predicts that 35 different Avr genes correspond to each one of these R genes
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
