Degree Type


Date of Award


Degree Name

Master of Science





First Advisor

Madan Bhattacharyya


Phytophthora sojae is a hemi-biotrophic oomycete pathogen that causes root and stem rot disease in soybeans. Nonhost resistance (NHR) is broad-spectrum and provides resistance against all non-adapted pathogen species. Limited information is known about the molecular mechanism of NHR. To better understand the molecular mechanism of NHR, I have mapped and identified candidates for two new Arabidopsis nonhost resistancje genes, P. sojae susceptible 5 (PSS5) and P. sojae susceptible 19 (PSS19), by studying two putative mutants pss5 and pss19, respectively, susceptible to the destructive soybean pathogen, P. sojae. Both mutants are also susceptible to Fusarium virguliforme that causes sudden death syndrome in soybean. By conducting bulked segregant analysis, the PSS5 and PSS19 were mapped to the south arm of chromosome 4 and north arm of chromosome 1, respectively. Comparison of the sequences of the bulked DNA samples from sixteen and twelve susceptible F2:3 families homozygous for the pss5 and pss19 alleles, respectively, with the reference Col-0 genome sequence revealed four candidate genes for PSS5 and six for PSS19. Analyses of the Salk T-DNA insertion mutants for these candidate genes identified the AT4G10470 gene for PSS5, and AT1G31930 for PSS19 as strong candidate genes. Complementation analysis of the pss5 mutant is being conducted to determine if AT4G10470 is the PSS5 gene and AT1G31930 is PSS19. Once these genes are identified, it will be feasible to investigate if anyone of them can confer resistance against the soybean pathogens P. sojae and/or F. virguliforme in transgenic soybean plants.

Copyright Owner

Yang Yang



File Format


File Size

40 pages

Included in

Genetics Commons