Localization of DIR1 at the tissue, cellular and subcellular levels during Systemic Acquired Resistance in Arabidopsis using DIR1:GUS and DIR1:EGFP reporters.


BACKGROUND: Systemic Acquired Resistance (SAR) is an induced resistance response to pathogens, characterized by the translocation of a long-distance signal from induced leaves to distant tissues to prime them for increased resistance to future infection. DEFECTIVE in INDUCED RESISTANCE 1 (DIR1) has been hypothesized to chaperone a small signaling molecule to distant tissues during SAR in Arabidopsis. RESULTS: DIR1 promoter:DIR1-GUS/dir1-1 lines were constructed to examine DIR1 expression. DIR1 is expressed in seedlings, flowers and ubiquitously in untreated or mock-inoculated mature leaf cells, including phloem sieve elements and companion cells. Inoculation of leaves with SAR-inducing avirulent or virulent Pseudomonas syringae pv tomato (Pst) resulted in Type III Secretion System-dependent suppression of DIR1 expression in leaf cells. Transient expression of fluorescent fusion proteins in tobacco and intercellular washing fluid experiments indicated that DIR1's ER signal sequence targets it for secretion to the cell wall. However, DIR1 expressed without a signal sequence rescued the dir1-1 SAR defect, suggesting that a cytosolic pool of DIR1 is important for the SAR response. CONCLUSIONS: Although expression of DIR1 decreases during SAR induction, the protein localizes to all living cell types of the vasculature, including companion cells and sieve elements, and therefore DIR1 is well situated to participate in long-distance signaling during SAR.





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Publication Info

Champigny, Marc J, Heather Shearer, Asif Mohammad, Karen Haines, Melody Neumann, Roger Thilmony, Sheng Yang He, Pierre Fobert, et al. (2011). Localization of DIR1 at the tissue, cellular and subcellular levels during Systemic Acquired Resistance in Arabidopsis using DIR1:GUS and DIR1:EGFP reporters. BMC plant biology, 11(1). p. 125. 10.1186/1471-2229-11-125 Retrieved from https://hdl.handle.net/10161/21726.

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Sheng-Yang He

Benjamin E. Powell Distinguished Professor of Biology

Interested in the fascinating world of plants, microbes or inter-organismal communication and co-evolution? Please contact Prof. Sheng-Yang He (shengyang.he@duke.edu; hes@msu.edu).

Millions of years of co-evolution between plants and microbes have resulted in an intricate web of attack, counter-attack, decoy, and hijacking mechanisms in biology. Moreover, co-evolution between plants and microbes is greatly impacted by ongoing climate change. In our lab, we probe “host-microbe-climate” interactions to answer the following fundamental questions: (1) How do microbial pathogens infect a susceptible host? (2) How do plants select beneficial microbiomes to ensure health? (3) How do climate conditions impact disease and immunity?      

We use contemporary methods to address these questions, including those commonly used in molecular genetics, genomics, biochemistry, cell biology, bioinformatics, microbiology, plant biology, co-evolution and infectious disease biology.    

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