Alkaloids production and antioxidant properties in Catharanthus roseus (L.) G. Don. shoots and study of alkaloid biosynthesis-related gene expression levels in response to methyl jasmonate and putrescine treatments as eco-friendly elicitors.

Abstract

This study aimed to determine the effects of methyl jasmonate (MJ) combined with putrescine as eco-friendly elicitors on secondary metabolism and gene expression of alkaloid biosynthetic pathway in Catharanthus roseus in vifro-propagated shoots. The expression of mitogen-activated protein kinase 3 and the transcription factor, octadecanoid-responsive Catharanthus AP2-domain3, upstream of plant alkaloids' biosynthetic pathway, and of key genes in the pathway (CrPRXl, STR, DAT, and GS) are investigated as well using qRt-PCR. Antioxidant enzyme (superoxide dismutase, peroxidase, and catalase) activities and non-enzymatic antioxidants (phenolics, flavonoids, and carotenoids) contents have studied to determine the stress levels of the plant by spectrophotometer. Results showed increased contents of non-enzymatic antioxidants after 4-8 hr and enzymatic antioxidants activities after 24 hr. Alkaloids contents increased mostly after 1 week. The investigated signaling genes upregulated after 8 hr and biosynthetic genes after 24 hr of treatments. Combined treatments had more positive effects on gene expression levels, antioxidant responses, and secondary metabolite production than MJ individually. Increased effects of combined elicitor on genes expression may be due to cross talks between their signaling pathways. Combination of MJ and putrescine can be used as an eco-friendly elicitor for enhancing the production of economically important alkaloids in C. roseus.