Tobacco plantlets ameliorate oxidative stress upon expression of a cryptogein gene

• Published in: Plant cell, tissue and organ culture tissue and organ culture, 2016-06, Vol.125 (3), p.553-570
• Main Authors: Kumar, Mahesh, Basu, Amrita, Kumari, Punam, Jha, Sumita, Mitra, Adinpunya
• Format: Article
• Language: English
• Subjects: Accumulation; Antioxidants; Biodegradation; Biomedical and Life Sciences; Chlorogenic acid; Chlorophyll; Enzymes; Flavonoids; Fungi; Gene expression; Hairy root; Hydrogen peroxide; Hypersensitive response; Leaves; Life Sciences; Lignin; Nicotiana tabacum; Original Article; Oxidation; Oxidative stress; Phenolic acids; Phenols; Plant Genetics and Genomics; Plant Pathology; Plant Physiology; Plant Sciences; Plant tissues; Plantlets; Reactive oxygen species; Salicylic acid; Superoxide; Tobacco; Transcription; Volatiles
• ISSN: 0167-6857; 1573-5044
• DOI: 10.1007/s11240-016-0970-0

Spontaneously-regenerated Nicotiana tabacum plantlets from hairy roots expressing a fungal elicitor protein β-cryptogein were assessed for their antioxidative responses. Enhanced activities of antioxidant enzymes as well as increased accumulation of non-enzymatic antioxidants such as chlorogenic acid were noted in Ri-crypt-transformed plantlets (RCTP) as compared to Ri-transformed plantlets (RTP). Although total phenolics, flavonoids and lignin content were boosted in RCTP, the contents of total chlorophyll did not show any significant change when compared with RTP plantlets. The RCTP plantlets showed an apparent reduction of oxidative stress indicators such as, H 2 O 2 , superoxide radicals and malonadialdehyde (MDA) contents when compared with RTP. Because of enhanced antioxidative mechanisms, the accumulations of ROS were suppressed in cryptogein-expressed plantlets. Although this might affect the hypersensitive response (HR) when cryptogein-expressed leaves were treated with fungal pathogens, the degradation of leaf tissues was however delayed due to the enhanced accumulation of wall-bound phenolic acids. Upliftment of PAL, 4CL and CAD activities was observed in RCTP as compared to RTP, and the transcript levels of these enzymes also reflected a similar trend, i.e. , enhanced expression in RCTP. However, suppressed levels of HMGR and DXS transcripts were observed in RCTP as compared to RTP. Contents of total terpenoid volatiles were also reduced in RCTP, while levels of methyl salicylate were found to be enhanced in these plantlets when compared with RTP. Thus, an apparent improvement of antioxidative status was evident in RCTP which may provide greater capacities to ameliorate oxidative stress encountered by these plantlets.