Cohn M, Bart RS, Shybut M, Dahlbeck D, Gomez M, Morbitzer R, Hou BH, Frommer WB, Lahaye T, Staskawicz BJ.

Mol Plant Microbe Interact. 2014 Nov;27(11):1186-98. doi: 10.1094/MPMI-06-14-0161-R.

Abstract

The gene-for-gene concept has historically been applied to describe a specific resistance interaction wherein single genes from the host and the pathogen dictate the outcome. These interactions have been observed across the plant kingdom and all known plant microbial pathogens. In recent years, this concept has been extended to susceptibility phenotypes in the context of transcription activator-like (TAL) effectors that target SWEET sugar transporters. However, because this interaction has only been observed in rice, it was not clear whether the gene-for-gene susceptibility was unique to that system. Here, we show, through a combined systematic analysis of the TAL effector complement of Xanthomonas axonopodis pv. manihotis and RNA sequencing to identify targets in cassava, that TAL20Xam668 specifically induces the sugar transporter MeSWEET10a to promote virulence. Designer TAL effectors (dTALE) complement TAL20Xam668 mutant phenotypes, demonstrating that MeSWEET10a is a susceptibility gene in cassava. Sucrose uptake-deficient X. axonopodis pv. manihotis bacteria do not lose virulence, indicating that sucrose may be cleaved extracellularly and taken up as hexoses into X. axonopodis pv. manihotis. Together, our data suggest that pathogen hijacking of plant nutrients is not unique to rice blight but also plays a role in bacterial blight of the dicot cassava.

See: http://www.ncbi.nlm.nih.gov/pubmed/25083909

Fig. 4. MeSWEET10a-targeted designer transcription activator-like effectors (dTALE) restore virulence defects of Xam668ΔTAL20. dTALE designed to target locations within the MeSWEET10apromoter were conjugated into Xam668ΔTAL20. Semiquantitative reverse-transcriptase polymerase chain reaction was used to confirm MeSWEET10atranscript induction 24 h postinoculation. Watersoaking symptom development was assessed at 5 days postinoculation for Xam668ΔTAL20 and dTALE-complemented strains inoculated at an optical density at 600 nm of 0.1. Experiments were re-peated three times with similar results. T = TAL.