Proteomic Analysis of Differentially Expressed Proteins in Resistant Soybean Leaves after Phakopsora pachyrhizi Infection

Soybean rust caused by Phakopsora pachyrhizi is a destructive foliar disease in nearly all soybean-producing countries. Understanding the host responses at the molecular level is certainly essential for effective control of the disease. To identify proteins involved in the resistance to soybean rust, differential proteomic analysis was conducted in soybean leaves of a resistant genotype after P.pachyrhizi infection. A total of 41 protein spots exhibiting a fold change >1.5 between the non-inoculated and P.pachyrhizi-inoculated soybean leaves at 12 and 24h postinoculation (hpi) were unambiguously identified and functionally grouped into seven categories. Twenty proteins were up-regulated and four proteins were down-regulated at 12hpi, whereas 18 proteins were up-regulated and eight proteins were down-regulated at 24hpi. Generally, proteins involved in photosynthesis were down-regulated, whereas proteins associated with disease and defense response, protein folding and assembly, carbohydrate metabolism and energy production were up-regulated. Results are discussed in terms of the functional implications of the proteins identified, with special emphasis on their putative roles in defense. Abundance changes of these proteins, together with their putative functions reveal a comprehensive picture of the host response in rust-resistant soybean leaves and provide a useful platform for better understanding of the molecular basis of soybean rust resistance.