Abstract:
Effects of yeast extract (YE) (0, 0.05, 0.1, 0.2, 0.5 and 1%) were investigated on
rosmarinic acid (RA) accumulation and tyrosine aminotransferase (TAT) gene expression
in Melissa officinalis seedlings at different time intervals (4 and 17 hours). Based on the
results, only YE concentrations of 0.05%, 0.1%, and 0.2%, for the 17-hour treatment,
significantly stimulated RA biosynthesis pathway. At this elicitation time, flavonoid
content and TAT gene expression significantly increased by the increase in YE
concentration up to 0.2% as compared to the control. The maximum amount for both of
them was seen at 0.1% YE treatment, where the RA accumulation was drastically
elevated. Furthermore, the aerial parts were improved when root lengths were decreased;
this was observed in seedlings that were treated by YE for 30 days. Overall, these
observations can be attributed to the oxidative stress induced by YE, as a consequence of
its uptake by the plant, as revealed by increasing activities in superoxide dismutase and
catalase.
Keywords: Antioxidant enzyme activity, Flavonoids, Elicitor, Morphological properties
