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

Abstract

AbstractShoots, 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. Copyright © 2005 Society of Chemical Industry