Proteomics-based study of host-fungus interaction between soybean and Phakopsora pachyrhizi using recombinant inbred line (RIL) derived sister lines

Abstract

Phakopsora pachyrhizi, the causal agent of Asian soybean rust (ASR), has the potential to cause severe yield losses as all United States commercial soybean varieties are susceptible. In this study, 10 soybean recombinant inbred line (RIL) derived sibling lines of two populations (RN06-32-2 and RN06-16-1) were evaluated for differences in response to infection by P. pachyrhizi. These lines, which had previously shown differential responses to Florida soybean rust isolates, were evaluated using Louisiana soybean rust isolates under both detached leaf assay and greenhouse in planta inoculation conditions. Sibling lines showed significant differences in response to P. pachyrhizi infection under both conditions. Lines 8-a, 8-b, 94-c of population RN06-32-2 and lines 15-b and 16-c of population RN06-16-1 showed a resistant response against Louisiana rust isolates in comparison with the immune response against Florida rust isolates. Whereas, lines 15-c and 16-b of population RN06-16-1 and lines 8-c, 94-a, and 94-b showed similar responses against Louisiana rust isolates as that of Florida rust isolates. Lines 15-c and 16-b showed moderately resistant response; lines 8-c, 94-a, and 94-b showed susceptible and resistant response, respectively. To understand the compatible and incompatible host-pathogen interactions at the molecular level, we conducted a time-course study (0 h, 10 h, 1 d, 2 d, 3 d, 4 d, 5 d, 8 d, 10 d, 12 d and 14 d) of P. pachyrhizi infection and compared protein profiles of 8-a (resistant) and 8-c (susceptible) lines in response to ASR inoculation, using DIGE proteomics. Based on the gel analysis, we observed approximately 100 differentially expressed spots between 8-a and 8-c lines. Among these, 37 proteins were identified using mass spectrometry. Most of the identified proteins are involved in photosynthesis and carbon metabolism, defense mechanism, seed storage and include some uncharacterized proteins.