Inheritance of virulence in the root rot pathogen Phytophthora sojae

The oomycete Phytophthora sojae causes stem and root rot of soybean plants. The interaction of pathogen avirulence (Avr) and host resistance (R)-genes determine the disease outcome. The Avr3a mRNA transcript level is variable among P. sojae strains and determines virulence towards the R-gene Rps3a. To study the inheritance of virulence, genetic crosses and self-fertilizations were performed. A cross between P. sojae strains ACR10 and P7076 causes transgenerational gene silencing of Avr3a allele, and this effect is meiotically stable up to the F5 generation. However, test-crosses of F1 (Avr3aACR10/Avr3aP7076) with strain P6497 result in expression of Avr3a in all progeny and release of silencing of the Avr3aP7076 allele. Progeny from P6497 X ACR10 crosses showed unusual inheritance for Avr3a expression. Overall, we conclude that Avr3a gene silencing is strain specific and could rely on epistatic factors. This study will lead to a better understanding of infection and virulence mechanisms that will help to better manage and safeguard soybean production.

Name thesis:degree_name

M Sc

Discipline thesis:degree_discipline

Biology

Grantor dc:publisher

The University of Western Ontario

Year dc:date.issued

2014

Author dc:creator

• Shrestha, Sirjana Devi

Advisor dc:contributor.advisor

• Mark Gijzen

• Phytophthora sojae
• soybean
• virulence
• avirulence
• genetic crosses
• oospore
• Avr3a gene
• transcript
• RT-PCR
• gene silencing
• epistatic
• gene conversion

Language dc:language.iso

en_ca

Handle dc:identifier.uri

https://hdl.handle.net/20.500.14721/35450

OAI identifier oai:identifier

oai:uwo.scholaris.ca:20.500.14721/35450