Grapevine response to a Dittrichia viscosa extract and a Bacillus velezensis strain

The present study aims to evaluate the response of the three Mediterranean local grapevines ‘Garnacha Blanca’, ‘Garnacha Tinta’, and ‘Macabeo’ to treatments with biocontrol products (BPs), a botanical extract (Akivi, Dittrichia viscosa extract) and a beneficial microorganism (Bacillus UdG, Bacillus velezensis). A combination of transcriptomics and metabolomics approaches were chosen in order to study grapevine gene expression and to identify gene marker candidates, as well as, to determine grapevine metabolites differentially concentrated in response to BPs treatments. Grapevine plants were cultivated in greenhouse controlled conditions and submitted to the treatments, and thereafter, leaves were sampled 24h after treatment to conduct gene expression study by RNA-sequencing for ‘Garnacha Blanca’ leaves extract and by RT-qPCR for the three cultivars. Differentially expressed genes (DEGs) were investigated for both treatments and highly influenced DEGs were selected to be tested in the three cultivars as treatment gene markers. In addition, extraction of leaf components was performed to quantify metabolites such as phytohormones, organic acids, and phenols. Considering all the upregulated and downregulated genes and enhanced metabolites concentrations, the treatments had an effect on jasmonic acid, ethylene, and phenylpropanoids defense pathways. In addition, several DEG markers were identified presenting a stable overexpression after the treatments in the three grapevine cultivars. These gene markers could be used to monitor the activity of the products in field treatments in future research. Further research will be necessary to confirm these first results under field conditions. The transcriptome of Vitis vinifera cv Garnacha Blanca plants treated by spray applications of a plant extract (Akivi, A) or a microbial (Bacillus UdG fresh culture or lyophilized, respectively B or BL) biocontrol products were compared to non-treated ones 24h post-treatment. Four biological replicates were used. Each biological replicate consisted of 10 grapevine leaves (2 leaves x 5 plants).