Differential roles of glucosinolates and camalexin at different stages of Agrobacterium-mediated transformation

Po-Yuan Shih; Shu-Jen Chou; Caroline Müller; Barbara Ann Halkier; Rosalia Deeken; Erh-Min Lai

doi:10.1111/mpp.12672

Differential roles of glucosinolates and camalexin at different stages of Agrobacterium-mediated transformation

Mol Plant Pathol. 2018 Mar 2;19(8):1956-1970. doi: 10.1111/mpp.12672. Online ahead of print.

Authors

Po-Yuan Shih^{1

2

3}, Shu-Jen Chou¹, Caroline Müller⁴, Barbara Ann Halkier⁵, Rosalia Deeken⁶, Erh-Min Lai^{1

2

7}

Affiliations

¹ Institute of Plant and Microbial Biology, Academia Sinica, 115 Taipei, Taiwan.
² Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, 115 Taipei, Taiwan.
³ Graduate Institute of Biotechnology, National Chung-Hsing University, 402 Taichung, Taiwan.
⁴ Chemical Ecology, Bielefeld University, 33615 Bielefeld, Germany.
⁵ Department of Plant and Environmental Sciences, DynaMo Center, University of Copenhagen, 1817 Frederiksberg C, Denmark.
⁶ Molecular Plant Physiology and Biophysics, Julius-von-Sachs-Institute for Biological Sciences, University of Wuerzburg, 97082 Wuerzburg, Germany.
⁷ Biotechnology Center, National Chung-Hsing University, 402 Taichung, Taiwan.

Abstract

Agrobacterium tumefaciens is the causal agent of crown gall disease in a wide range of plants via a unique interkingdom DNA transfer from bacterial cells into the plant genome. Agrobacterium tumefaciens is capable of transferring its T-DNA into different plant parts at different developmental stages for transient and stable transformation. However, the plant genes and mechanisms involved in these transformation processes are not well understood. We used Arabidopsis thaliana Col-0 seedlings to reveal the gene expression profiles at early time points during Agrobacterium infection. Common and differentially expressed genes were found in shoots and roots. A gene ontology analysis showed that the glucosinolate (GS) biosynthesis pathway was an enriched common response. Strikingly, several genes involved in indole glucosinolate (iGS) modification and the camalexin biosynthesis pathway were up-regulated, whereas genes in aliphatic glucosinolate (aGS) biosynthesis were generally down-regulated, on Agrobacterium infection. Thus, we evaluated the impacts of GSs and camalexin during different stages of Agrobacterium-mediated transformation combining Arabidopsis mutant studies, metabolite profiling and exogenous applications of various GS hydrolysis products or camalexin. The results suggest that the iGS hydrolysis pathway plays an inhibitory role on transformation efficiency in Arabidopsis seedlings at the early infection stage. Later in the Agrobacterium infection process, the accumulation of camalexin is a key factor inhibiting tumour development on Arabidopsis inflorescence stalks. In conclusion, this study reveals the differential roles of GSs and camalexin at different stages of Agrobacterium-mediated transformation and provides new insights into crown gall disease control and improvement of plant transformation.

Keywords: Agrobacterium tumefaciens; Agrobacterium-mediated transformation; camalexin; crown gall; glucosinolates; plant defence; transcriptome.