Submitted to: Biomed Central (BMC) Genomics
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/31/2013
Publication Date: 9/11/2013
Citation: Tremblay, A., Hosseini, P., Li, S., Alkharouf, N.W., Matthews, B.F. 2013. Analysis of Phakopsora pachyrhizi transcript abundance in critical pathways at four time-points during infection of a susceptible soybean cultivar using deep sequencing. Biomed Central (BMC) Genomics. 14:614. Interpretive Summary: Soybean rust is a fungal disease that attacks soybean and can greatly decrease yield. The rust entered the USA in 2004, and it has caused some losses in Southern states. Although crop losses are low in the USA, losses in many other countries are large. Therefore, scientists are studying the interaction of the fungus with soybean, and they are looking for ways to increase resistance of soybean to this fungus to ensure soybean yield losses do not increase in the future. Therefore, we examined the expression of genes in the fungus at four different time points through its life cycle. We identified genes that are highly expressed that may be candidates to make soybean resistant to the fungus. This information is of interest to scientists and companies working to improve resistance of soybean to soybean rust.
Technical Abstract: Phakopsora pachyrhizi, the agent responsible for soybean rust, is among the top hundred most virulent plant pathogens and can cause soybean yield losses of up to 80% when appropriate conditions are met. We used mRNA-Seq by Illumina to analyze pathogen gene expression at 15 seconds (s), 7 hours (h), 48 h, and 10 days (d) after inoculation (ai) of susceptible soybean leaves with P. pachyrhizi. We discovered that energy, nucleotide metabolism, and protein synthesis are major priorities for the fungus during infection and development. Also at early steps of infection (7 and 48 hai), many mRNAs encode unknown proteins with signal peptides which are common to fungal virulence factors. During sporulation at 10 dai, the fungus still required carbohydrate metabolism, but there also was increased expression of mRNAs encoding enzymes involved in fatty acid metabolism. This information provides insight into molecular events and their timing throughout the life cycle of the P. pachyrhizi, and it may be useful in the development of new methods of broadening resistance of soybean to soybean rust.