Production of dextran in transgenic potato plants

The production of dextran in potato tubers and its effect on starch biosynthesis were investigated. The mature dextransucrase (DsrS) gene from Leuconostoc mesenteroides was fused to the chloroplastic ferredoxin signal peptide (FD) enabling amyloplast entry, which was driven by the highly tuber-expressed patatin promoter. After transformation of two potato genotypes (cv. Kardal and the amylose-free (amf) mutant), dextrans were detected by enzyme-linked immunosorbent assay (ELISA) in tuber juices of Kardal and amf transformants. The dextran concentration appeared two times higher in the Kardal (about 1.7 mg/g FW) than in the amf transformants. No dextran was detected by ELISA inside the starch granule. Interestingly, starch granule morphology was affected, which might be explained by the accumulation of dextran in tuber juices. In spite of that, no significant changes of the physicochemical properties of the starches were detected. Furthermore, we have observed no clear changes in chain length distributions, despite the known high acceptor efficiency of DSR

Improved cassava starch by antisense inhibition of granule-bound starch synthase I

Cassava is a poor man's crop which is mainly grown as a subsistence crop in many developing countries. Its commercial use was first as animal feed (also known as tapioca), but has shifted since the late sixties to a source of native starch. The availability of native starches, which on the one hand do not require substantial chemical derivatisation and on the other hand have improved properties, would make cassava also for small farmers a potentially attractive cash crop. Since breeding is difficult in this polyploid, vegetatively propagated, crop a transgenic approach would be ideal to improve certain characteristics. We have created a cassava genotype producing amylose-free starch by genetic modification. The absence of amylose increased the clarity and stability of gels made with the transgenic starch, without requiring treatment with environment-unfriendly chemicals such as epoxides (propylene oxide, ethylene oxide) and acetic anhydride, which are normally used to improve stability. The amylose-free starch showed no changes in particle size distribution, chain length distribution or phosphorous content when compared to amylose-containing starch, but the granule melting temperature was increased by almost 2°C. Furthermore, the amylose-free cassava starch shows enhanced clarity and stability properties. These improved functionalities are desired in technical applications in paper and textile manufacturing, but also in the food industry for the production of sauces, dairy products and noodle

Elektroforese en plantenveredelingsonderwijs.

Een standaardmethode is beschreven voor de zuiverheidscontrole van zaden van koolgewassen, uitgewerkt als practicumproef voor grote groepen tweedejaars studenten plantenveredeling. Het principe van de methode, de proefuitvoering en het resultaat zijn uiteengeze

Diversity for enzymes, flowering behaviour and purple plant colour of perennial kale (Brassica oleraceae L. var. ramosa DC) in the Netherlands.

Perennial kale has probably been domesticated and distributed by the Romans. Some relic populations are still being grown in various parts of western Europe (Ireland, Scotland, England, the Netherlands, Belgium, France, Portugal), in Ethiopia, in Brazil and Haiti up to the present. Most accessions of perennial kale grown in gardens in the Dutch province Limburg have lost their flowering ability. Some of them flower occasionally, others every year. No explanation can be given for this inconstant behaviour. This predominantly diploid material is quite uniform for the enzymes acid phosphatase (ACD), esterase (EST), glutamate oxaloacetate transaminase (GOT) and shikamata dehydrogenase (SKD). The same is true for presence of anthocyanins in the leaves. The 40 fully investigated accessions could be grouped into 8 phenotypes: 26 with phenotype 1 (at least 9 are tetraploid), three with phenotype 2, six with phenotype 3, and one for each of the phenotypes 4 to 8. Accessions with phenotypes 2 and 3 had the same phenotype for the four enzymes as phenotype 1, and so have most of the 13 accessions, only investigated for enzymes