Sammanfattning

The seed oil in Macadamia integrifolia contains about 30% palmitoleic acid (16:1(Delta 9)) and Nerium oleander about 12% isoricinoleic acid (Delta 9-hydroxy-18:1(Delta 12)). It has been shown that palmitoleic acid can be produced by acyl-acyl carrier protein (ACP) desaturases and it has also been shown that fatty acid hydroxylation can occur via direct substitution of a hydrogen atom. Therefore it seemed possible that the enzymes responsible for the making of these unusual fatty acids in M. integrifolia and N. oleander were of acyl-ACP desaturase type. Extracts from developing M. integrifolia developing seeds showed a relative ratio of 16:0-ACP to 18:0-ACP desaturation that was about 13 times higher than in sunflower seeds. N. oleander seed extracts catalysed conversion of 18:0-ACP to 18:1(Delta 9) but only trace amounts of Delta 9-hydroxy fatty acids were formed. A total of four cDNAs were isolated from developing seeds, of both species, using a fragment isolated with PCR amplification. The M. integrifolia acyl-ACP desaturase cDNA was expressed in Escherichia coli. A partly purified fraction of the enzyme showed a 16:0-ACP to 18:0-ACP desaturation ratio about 90-fold less than that in the Macadamia extracts. Expressed N. oleander acyl-ACP desaturase cDNAs showed predominantly 18:0-ACP desaturase activity and no hydroxylase activity. Thus it is not likely that any of the four acyl-ACP desaturases cloned from M. integrifolia or N. oleander is involved in the production of unusual fatty acids. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.

Nyckelord

acyl-ACP desaturase; Macadamia integrifolia; Nerium oleander

Publicerad i

Plant Science
2000, Volym: 154, nummer: 1, sidor: 53-60
Utgivare: ELSEVIER SCI IRELAND LTD

SLU författare

• Gummeson, Per Olof

  • Institutionen för växtförädling, Sveriges lantbruksuniversitet
    

• Lenman, Marit

  • Institutionen för växtförädling, Sveriges lantbruksuniversitet
    

• Stymne, Sten

  • Institutionen för växtförädling, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Biokemi och molekylärbiologi


Publikationens identifierare

DOI: https://doi.org/10.1016/S0168-9452(99)00268-X

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/52294