PT  - JOURNAL ARTICLE
AU  - Gaucher Matthieu
AU  - Righetti Laura
AU  - Aubourg Sébastien
AU  - Dugé de Bernonville Thomas
AU  - Brisset Marie-Noëlle
AU  - Chevreau Elisabeth
AU  - Vergne Emilie
TI  - An <em>Erwinia amylovora</em> inducible promoter for intragenic improvement of apple fire blight resistance
AID  - 10.1101/767772
DP  - 2019 Jan 01
TA  - bioRxiv
PG  - 767772
4099  - http://biorxiv.org/content/early/2019/10/04/767772.short
4100  - http://biorxiv.org/content/early/2019/10/04/767772.full
AB  - Intragenesis is an important alternative to transgenesis to produce modified plants containing native DNA only. A key point to develop such a strategy is the availability of regulatory sequences controlling the expression of the gene of interest. With the aim of finding apple gene promoters either inducible by the fire blight pathogen Erwinia amylovora (Ea) or moderately constitutive, we focused on polyphenoloxidase genes (PPO). These genes encode oxidative enzymes involved in many physiological processes and have been previously shown to be up-regulated during the Ea infection process. We found ten PPO and two PPO-like sequences in the apple genome and characterized the promoters of MdPPO16 (pPPO16) and MdKFDV02 PPO-like (pKFDV02) for their potential as Ea-inducible and low-constitutive regulatory sequences respectively. Expression levels of reporter genes fused to these promoters and transiently or stably expressed in apple were quantified after various treatments. Unlike pKFDV02 which displayed a variable activity, pPPO16 allowed a fast and strong expression of transgenes in apple following Ea infection in a Type 3 Secretion System dependent manner. Altogether our results indicate that pKFDV02 did not keep its promises as a constitutive and weak promoter whereas pPPO16, the first Ea-inducible promoter cloned from apple, can be a useful component of intragenic strategies to create fire blight resistant apple genotypes.