Laser Irradiation Induces DNA Polymorphism and Alters Phytochemicals Compositions as well as Growth and Yield of Curcuma longa

Curcuma longa , commonly known as curcuma or turmeric is a perennial herbaceous plant native to Indian subcontinent and Southeast Asia. Its underground part, referred as rhizome, is used for vegetative propagation and source for remedies for various illnesses. Curcuminoid and volatile oils are the major active components found in turmeric, the yellow power obtained from the ground rhizome. He-Ne laser irradiation has been used as biostimulator device to enhance plant growth. In this study, we have pre-treated the curcuma rhizomes with 5, 10- or 15-min He-Ne laser irradiation. Laser pre-treated and non-treated rhizomes were then cultivated in greenhouse for 8 months. The growth parameters, photosynthetic pigment contents, rhizomes yield were measured. The phytochemical compositions of rhizomes from different treatment groups were measured by gas chromatography mass spectrometry and compared. Effects of laser on DNA polymorphism was assessed by ISSR markers. Our results indicated that laser pre-treatments on rhizomes enhanced curcuma plant height, number of roots and rhizomes, rhizomes diameters, and dried weight of leaves and rhizomes, as well as photosynthetic pigments. The enhancement effects are more prominent in 10 min treatment groups. In addition, laser treatment also alters the phytochemical compositions of ethanol extract from the rhizomes. Interestingly, our study has revealed that laser treatment had resulted in DNA polymorphism as shown from the analysis by ISSR markers.