|Link, Tobias -|
|Lang, Patrick -|
|Van DE Mortel, Martijn -|
|Voegele, Ralf -|
|Mendgen, Kurt -|
|Baum, Thomas -|
|Whitham, Steven -|
Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 6, 2013
Publication Date: April 3, 2014
Citation: Link, T.I., Lang, P., Scheffler, B.E., Duke, M.V., Graham, M.A., Cooper, B., Tucker, M.L., Van De Mortel, M., Voegele, R.T., Mendgen, K., Baum, T.J., Whitham, S.A. 2014. The haustorial transcriptomes of Uromyces appendiculatus and Phakopsora pachyrhizi and their candidate effector families. Molecular Plant Pathology. 15(4):379-393. DOI:10.1111/mpp.12099. Interpretive Summary: A major type of economically important plant diseases are those classified as “rusts.” Rust fungi produce a haustoria which is an appendage that penetrates the plant and draws nutrients from the host. In order to overcome the defenses of the plant, the haustoria secretes proteins that suppress the plant’s innate defense system. If the development or function of the haustoria is interrupted then infection of the plant or possible spread of the rust could be prevented. Thus it would be desirable to understand which genes are expressed within haustoria for understanding the interactions between the host plant and the rust, and possibly for identifying targets for controlling the pathogen. This study concentrated on two economically important rust pathogens Phakopsora pachyrhizi and Uromyces appendiculatus, the causative agents of Asian soybean rust and Common bean rust, which cause extensive yield loss in their respective legume host crops i.e. soybean and common bean. High throughput DNA sequencing technology was used to identify haustoria expressed genes and bioinformatic techniques were used to classify the genes and identify those that may be responsible for secreted proteins which interact with the host. These defined comprehensive sets of haustoria related genes opens the door for critical comparative analysis of rust haustoria genes and those associated with host-pathogen interactions.
Technical Abstract: The haustoria of the biotrophic rust fungi are responsible for the uptake of nutrients from host cells, and they produce secreted proteins known as effectors that suppress host defenses. Effectors hold essential keys for elucidating the plant-fungal interactions, and they are promising targets for pathogen control. Here, we studied the haustoria transcriptomes of Phakopsora pachyrhizi and Uromyces appendiculatus, the causative agents of Asian soybean rust and Common bean rust, which cause extensive yield loss in their respective legume host crops. To generate the haustorial transcriptomes, we used pyrosequencing to sequence copy DNA synthesized from messenger RNA extracted from haustoria of P. pachyrhizi and U. appendiculatus. Bioinformatic approaches were used to annotate the resulting sequences, identify gene families, and predict secreted proteins. Families of secreted proteins that were identified only in rust fungi or that were specific to family, genus or species were deemed to be good effector candidates. This work establishes comprehensive sets of candidate effector proteins for the legume rust pathogens, P. pachyrhizi and U. appendiculatus, and provides a foundation for comparative analysis of haustorial gene expression that gives further insight into evolution of host specificities.