Determination of seed priming activity of β-aminobutyric acid (BABA) and its effect against Clavibacter michiganensis ssp michiganensis (Cmm) in tomato (Solanum lycopersicum L. )

Many stress factors cause yield and quality losses in agricultural production, from the increasing world population to the decrease in agricultural areas. In order to increase the yield and quality of agricultural production, it is necessary to protect plants against pathogens. Seed-priming is the practice of improving germination and seedling development by subjecting the seed to certain pre-treatments before germination. Seed-priming applications are made in order to increase the yield and the equivalent and rapid germination of the plants. Plant defense elicitors that stimulate the plant's natural immune system when applied to the plant externally, thereby strengthening the plant and making it more resistant and stronger against plant pests. β-Aminobutyric Acid (BABA) is one of these plant defense elicitors. In our study, the effect of BABA-seed priming on Clavibacter michiganensis ssp michiganensis (Cmm), which causes bacterial cancer in tomato (Solanum lycopersicum L.), was investigated. Tomato seeds were subjected to seed-priming for 72 hours with 12 mM BABA (BABA-Priming) or water (Su-Priming) as the control group. Normally germinated tomato seedlings were used as positive control. When the plant reached to 3-4 leaf stage, it is infected with Cmm. As a result of the findings, BABA-Priming was the experimental group that reduced the severity of the disease the most. In addition, it has been determined that the application of BABA as a spray or water-priming application provides effective protection compared to the control. In order to understand the molecular mechanism of this suppression, plant samples were taken from two different time points (0h and 7th day) and transcriptional changes of important plant immunity genes (NPR1, PAL, PR1, WRKY70, WRKY33b, TPK1b, and PR5) were examined. According to qRT-PCR results, it was observed that NPR1 gene expression increased significantly with BABA-Priming application compared to control. NPR1 gene expression increased approximately 5 times with BABA-Priming application at the 0th hour. In addition, BABA-priming caused upregulation of PR1 gene expression. In addition, foliar spraying of BABA (BABA-priming+BABA-Sp) to seed primed plants resulted in a nine fold increase in PR1 gene expression. Along with the regulation of other genes, the molecular infrastructure of BABA seed priming has been tried to be revealed. In line with the results obtained in our study, it is predicted that BABA-seed priming application will contribute to the literature and have positive effects in terms of plant protection.