Field testing and exploitation of genetically modified cassava with low-amylose or amylose-free starch in Indonesia

The development and testing in the field of genetically modified -so called- orphan crops like cassava in tropical countries is still in its infancy, despite the fact that cassava is not only used for food and feed but is also an important industrial crop. As traditional breeding of cassava is difficult (allodiploid, vegetatively propagated, outbreeding species) it is an ideal crop for improvement through genetic modification. We here report on the results of production and field testing of genetically modified low-amylose transformants of commercial cassava variety Adira4 in Indonesia. Twenty four transformants were produced and selected in the Netherlands based on phenotypic and molecular analyses. Nodal cuttings of these plants were sent to Indonesia where they were grown under biosafety conditions. After two screenhouse tests 15 transformants remained for a field trial. The tuberous root yield of 10 transformants was not significantly different from the control. Starch from transformants in which amylose was very low or absent showed all physical and rheological properties as expected from amylose-free cassava starch. The improved functionality of the starch was shown for an adipate acetate starch which was made into a tomato sauce. This is the first account of a field trial with transgenic cassava which shows that by using genetic modification it is possible to obtain low-amylose cassava plants with commercial potential with good root yield and starch quality

Glycine max non-nodulation locus rj1: A recombinogenic region encompassing a SNP in a lysine motif receptor-like kinase (GmNFR1α)

The rj1 mutation of soybean is a simple recessive allele in a single line that arose as a spontaneous mutation in a population; it exhibits non-nodulation with virtually all Bradyrhizobium and Sinorhizobium strains. Here, we described fine genetic and physical mapping of the rj1 locus on soybean chromosome 2. The initial mapping of the rj1 locus using public markers indicated that A343.p2, a sequence-based marker that contains sequence similar to a part of the LjNFR1 gene regulating nodule formation as a member of lysin motif-type receptor-like kinase (LYK) family, maps very close to or cosegregates with the rj1 locus. The sequence of A343. p2 is 100% identical to parts of two BAC clone sequences (GM_WBb0002O19 and GM_WBb098N11) that contain three members of the LYK family. We analyzed the sequence contig (262 kbp)of the two BAC clones by resequencing and subsequent fine genetic and physical mapping. The results indicated that rj1 is located in a gene-rich region with a recombination rate of 120 kbp/cM: several fold higher than the genome average. Among the LYK genes, NFR1α is most likely the gene encoded at the Rj1 locus. The non-nodulating rj1 allele was created by a single base-pair deletion that results in a premature stop codon. Taken together, the fine genetic and physical mapping of the Rj1-residing chromosomal region, combined with the unexpected observation of a putative recombination hotspot, allowed us to demonstrate that the Rj1 locus most likely encodes the NFR1α gene

Genetic analysis of ethylene regulation of legume nodulation

The gaseous hormone ethylene has multiple roles in plant development and responses to external cues. Among these is the regulation of ‘Rhizobium’-induced nodulation in legumes. Extensive descriptive literature exists, but has been expanded to allow more mechanistic analysis through the application of genetics. Both mutants and transgenics displaying ethylene insensitivity have now been described, suggesting an intimate interplay of ethylene response, plant development and nodulation