In vitro culture of Pandanus amaryllifolius and enhancement of 2-acetyl-1-pyrroline, the major flavouring compound of aromatic rice, by precursor feeding of L-proline
2005
Thimmaraju, R. | Bhagyalakshmi, N. | Narayan, M.S. | Venkatachalam, L. | Ravishankar, G.A.
Shoots, plantlets and semi-differentiated callus (SDC) cultures of Pandanus amaryllifolius capable of producing high levels of basmati rice flavour were established in vitro using Murashige and Skoog nutrient medium. A total of 10% of the initial explants responded to produce shoot cultures in the presence of benzylamino purine (BAP) (0.5 mg L(-1)) and glutamine (100 mg L(-1)). Leaf explants and basal portions of shoots produced SDC whereas elongated in vitro shoots could be continuously multiplied, using BAP (1.5 mg L(-1)) and kinetin (Kn) (1.0 mg L(-1)), and rooted in half-strength medium for ex vitro cultivation leading to a process of micropropagation. Steam-distillation extraction (SDE) followed by gas chromatography-mass spectrometry (GC-MS) analysis of various cultured organs and spent liquid medium used for SDC revealed the presence of 2-acetyl-1-pyrroline (2-AP) to various extents. This 2-AP compound has been identified as the major flavouring compound of scented basmati and other scented rice varieties. 2-AP was found to be highest, on a fresh weight basis, in SDC (19.7 mg kg(-1)) on the 40th day, whereas in vitro roots, shoots and field leaves (of one-year-old plant) had lower levels of 15, 6.8 and 14 mg kg(-1), respectively. Further enhancement of 2-AP in SDC using precursor was possible by feeding into medium 1 mmol L(-1) of L-proline where a highest level of 21.67 ppm of 2-AP accumulated on the seventh day whereas a higher level of 2 mmol L(-1) of L-proline suppressed 2-AP levels. The present report is the first on the tissue culture studies of P. amaryllifolius where continuous production of plantlets as well as synthesis of high levels of 2-AP has been documented.
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