Whole-transcriptome microarray analysis of Pseudomonas syringae pv. actinidiae (Psa) treated with Gunpowder green tea extract (EGCG 0.4 mg/ml)

Purpose: Microarray technologies provide a unique opportunity to deeply investigate bacterial molecular responses to treatments. Pseudomonas syringae pv. actinidiae (Psa) is the causal agent of the bacterial canker of kiwifruit causing severe economic losses worldwide. At present, integrated control strategies include chemical treatments with copper-based products and preventive measures but the high virulence and fast spreading of the bacterium are hardly controlled by such measures, and especially copper use is questioned because of the possible appearance of copper resistant bacterial strains. The present project aims at the identification of Psa responses to green tea treatment (Gunpowder variety) at sub-lethal concentration (0.4 mg/ml). Methods: Psa cells were cultured in liquid KB (controls) or in KB supplemented with Gunpowder tea (Gunpowder-trateted) at 0.4 mg/ml EGCG for 24 h at 28°C. The microarray experiments on Gunpowder treated or untreated samples in biological triplicate resulted in 6 samples to be analyzed. Conclusions: This work identified important molecular mechanisms involved in Psa responses upon Gunpowder green tea treatment. mRNA profiles of Psa cells treated 24 h with Gunpowder tea extract (0.4 mg/ml) were compared to mRNA profiles of untreated Psa cells. All mRNA profiles were generated from three biological replicates.