The Role of Methyl Jasmonate During the Biotic Stress in Matricaria Chamomilla L.

Abstract The objective of the present study was to evaluate the effect of methyl jasmonate (MeJA) in plant resistance to polyphagous thrips. Eight-weeks old diploid and tetraploid chamomile plants ( Matricaria chamomilla ) in stage of leaf-rosettes were pre-treated with 0.22 mM MeJA for 72 h and then co-cultivated with thrips for next 96 h. In both cultivars, there was an increase in the content of hydrogen peroxide and superoxide radical, with a maximum in plants after thrips infestation. The pre-treatment with MJ led to a reduction, but the measured values were still higher than those in the control plants. The accumulation of total phenols and flavonoids corresponded with the activity of phenylalanine ammonia-lyase (PAL). The highest PAL activity and the highest levels of total phenols were observed in plants infected with thrips. MeJA pre-treatment slightly decreased their values. Within the cultivars we noticed differences in the accumulation of monitored coumarins: ( Z )- and ( E )-GMCA, herniarin and umbelliferone. In diploids MeJA significantly ameliorated their accumulation caused by thrips. On the other hand, in tetraploids, changes were minimal. The amount of umbelliferone sharply increased in both cultivars which points to its role as a stress metabolite.