Insights into nuclear DNA content, hydrogen peroxide and antioxidative enzyme activities during transverse thin cell layer organogenesis and ex vitro acclimatization of Malaxis wallichii, a threatened medicinal orchid
Autor: | Hiranjit Choudhury, Pramod Tandon, Suman Kumaria, Biswajit Bose |
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Rok vydání: | 2017 |
Předmět: |
0106 biological sciences
0301 basic medicine Physiology Glutathione reductase Organogenesis Plant Science Biology 01 natural sciences Acclimatization 03 medical and health sciences 030104 developmental biology Murashige and Skoog medium Catalase Botany Shoot biology.protein Molecular Biology Research Article 010606 plant biology & botany Explant culture Peroxidase |
Zdroj: | Physiology and Molecular Biology of Plants. 23:955-968 |
ISSN: | 0974-0430 0971-5894 |
Popis: | Malaxis wallichii (Lindl.) Deb, a small, perennial, monopodial, terrestrial orchid, is endemic to tropical Himalayas at an altitude of 1200–2000 m asl. The pseudobulbs are important ingredients of century old drug ‘Ashtavarga’ and a polyherbal energetic tonic ‘Chyavanprash’. An efficient genetically stable in vitro propagation protocol using transverse thin cell layer culture system was established for M. wallichii. In the present report, meta-topolin alone proved to be three times more beneficial compared to other routinely used cytokinins in inducing highest number of shoot buds, plant height and growth of regenerated shoots. The highest regeneration frequency (89%) along with maximum number of adventitious shoots per explant (22.5 ± 0.6) was observed in MS medium supplemented with 1.0 mg/l meta-topolin and 0.5 mg/l α-naphthalene acetic acid. Highest rooting frequency with highest number of roots (8.66 ± 0.3) was achieved in half-strength MS medium fortified with 1.0 mg/l indole acetic acid. Clonal stability of in vitro-derived plantlets was evaluated and compared to donor plant using intron splice junction (ISJ) markers and flow cytometry. ISJ markers revealed 4.76% clonal variability indicating high degree of genetic stability amongst the in vitro-derived regenerants. The nuclear DNA content of M. wallichii (2n) was found to be 2C = 2.760 ± 0.02 pg and therefore, 1349.64 Mbp (1C). Flow cytometry analysis of actively growing young and mature leaves from donor as well as in vitro-derived plantlets revealed presence of three peaks corresponding to 2C, 4C and 8C, while 2C was the most abundant. In the present investigation, there was no significant difference in the 2C DNA content between the mother and in vitro-derived plants; however, the frequency of endopolyploid cells varied in young and adult plants. An increased H2O2 content as well as lipid peroxidation activities were observed during early stages of acclimatization which declined afterwards. The enhanced activities of antioxidant enzymes like superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase in acclimatized plantlets as compared to in vitro-grown ones revealed their active involvement in growth and development against oxidative stress under external adverse environment. |
Databáze: | OpenAIRE |
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