Obiettivo The cassava plant accumulates the cyanogenic glucosides linamarin and lotaustralin in its edible roots and leaves. Mechanical injury of the plant tissue causes the release of beta-glucosidases and beta-hydroxynitrile lyases which results in the hydrolysis of these Cyanogenic glucosides causing the liberation of cyanide. The presence 0E cyanide in cassava derived products constitutes a serious nutritional health hazard and results in cronic or acute cyanide poisoning in populations where the supply of other food elements is limited. To minimize these adverse effects, breeding Programmes have been carried out and some improved cassava lines with a lower content of cyanogenic glucosides obtained. The cyanide content is known to vary depending o the growth conditions and so far it has not been possible to obtain acyanogenic cassava varieties. In the current STD 2 progranme we have (i) obtained a microsomal enzyme system from etiolated seedlings of cassava catalyzing the in vitro synthesi of cyanogenic glucosides; (ii) elucidated the pathway for biosynthesis of cyanogenic glucosides; (iii) demonstrated the involvement of cytochrome P45 in the pathway; (iv) purified the membrane proteins cytochrome P450, NADPH-cytochrome P450 oxidoreductase, NADH-cytochrome b5 oxidoreductase and cytochrome bs involved; (v) purified the soluble proteins UDPG-glucosyltransferase, beta-glucosidaseand.x-hydroxynitrilelyase; (vi) identified cdna clones for NADPH-cytochrome P450 oxidoreductase (also sequenced), UDPG-glucosyl transferase and beta-glucosidase (also sequenced); (vii) shown that beta-glucosidase and x-hydroxynitrilase genes are:expressed primarily in young latex vesicles. The overall aim has been to understand the biochemical, molecular biological and physiological processes behind the phenomenon ofcyanogenesis The present proposal constitutes an extension of these studies. It is important to isolate and characterize both structural- genes and control sequences for the components of cyanogenesis so that a rtional strategy for crop improvement can be produced. It is critical to understand the physiological factors important for regulation of cyanogenesis. The availability of the relevant gene probes and specific antibodies will permit efficient screening of new cassava cultivars obtained by traditional plant breeding. Campo scientifico natural scienceschemical sciencesinorganic chemistryinorganic compoundsagricultural sciencesagriculture, forestry, and fisheriesagricultureagronomyplant breedingnatural sciencesbiological sciencesbiochemistrybiomoleculesproteinsenzymes Programma(i) FP3-STD 3 - Specific research and technological development programme (EEC) in the field of the life sciences and technologies for developing countries, 1990-1994 Argomento(i) Data not available Invito a presentare proposte Data not available Meccanismo di finanziamento CSC - Cost-sharing contracts Coordinatore THE ROYAL VETERINARY AND AGRICULTURAL UNIVERSITY Contributo UE Nessun dato Indirizzo 40,Thorvaldsensvej 40 1871 FREDERISKSBERG Danimarca Mostra sulla mappa Costo totale Nessun dato Partecipanti (3) Classifica in ordine alfabetico Classifica per Contributo UE Espandi tutto Riduci tutto Mahidol University Thailandia Contributo UE Nessun dato Indirizzo Rama VI Road 10400 Bangkok Mostra sulla mappa Costo totale Nessun dato Oyo State University of Technology Nigeria Contributo UE Nessun dato Indirizzo Ogbomoso Mostra sulla mappa Costo totale Nessun dato UNIVERSITY OF NEWCASTLE UPON TYNE Regno Unito Contributo UE Nessun dato Indirizzo Framlington Place NE2 4HH NEWCASTLE UPON TYNE Mostra sulla mappa Costo totale Nessun dato