Broad Chain-Length Specificity of the Alkane-Forming Enzymes NoCER1A and NoCER3A/B in Nymphaea odorata.

Many terrestrial plants produce large quantities of alkanes for use in epicuticular wax and the pollen coat. However, their carbon chains must be long to be useful as fuel or as a petrochemical feedstock. Here, we focus on Nymphaea odorata, which produces relatively short alkanes in its anthers. We identified orthologs of the Arabidopsis alkane biosynthesis genes AtCER1 and AtCER3 in N. odorata and designated them NoCER1A, NoCER3A and NoCER3B. Expression analysis of NoCER1A and NoCER3A/B in Arabidopsis cer mutants revealed that the N. odorata enzymes cooperated with the Arabidopsis enzymes and that the NoCER1A produced shorter alkanes than AtCER1, regardless of which CER3 protein it interacted with. These results indicate that AtCER1 frequently uses a C30 substrate, whereas NoCER1A, NoCER3A/B and AtCER3 react with a broad range of substrate chain lengths. The incorporation of shorter alkanes disturbed the formation of wax crystals required for water-repellent activity in stems, suggesting that chain-length specificity is important for surface cleaning. Moreover, cultured tobacco cells expressing NoCER1A and NoCER3A/B effectively produced C19-C23 alkanes, indicating that the introduction of the two enzymes is sufficient to produce alkanes. Taken together, our findings suggest that these N. odorata enzymes may be useful for the biological production of alkanes of specific lengths. 3D modeling revealed that CER1s and CER3s share a similar structure that consists of N- and C-terminal domains, in which their predicted active sites are respectively located. We predicted the complex structure of both enzymes and found a cavity that connects their active sites.

Comparative study on the physicochemical and functional properties of the mucilage in the carpel of Nymphaea odorata using ultrasonic and classical heating extractions.

The cooked carpel of Nymphaea odorata has a large amount of transparent mucilage; however, the basic characteristics of this mucilage have not yet been reported. This study compared the physicochemical and functional properties of this mucilage obtained using conventional hot water extraction (HWM) and ultrasonic-assisted extraction (UAM). Neither HWM nor UAM affected the viability of mouse skin fibroblasts (NIH/3 T3) below 100 µg/mL. UAM had a higher yield production, phenol concentration, and in vitro antioxidant activity, but it had a lower viscosity and water-holding capacity than that of HWM. The Fourier transform infrared spectra revealed that the dialyzed HWM and UAM, named HWMD and UAMD, respectively, appeared to have major spectral differences at 1730 cm-1 and 1605 cm-1, implying that the degree of methylation was different between HWMD and UAMD. Compared to HWMD, UAMD in low-molecular weight polysaccharides increased. Indeed, the basic characteristics of native mucilage in the carpel of N. odorata were greatly changed by various extractions. Nevertheless, sugar analysis indicated that glucuronic acid was the main composition of HWMD and UAMD.