CBN-V Video Archives - S3-08
Changes in Starch Pattern of a g- Irradiated Induced Mutant of Cassava

Joseph R., T. Joseph, H.H. Yeoh and C.S. Loh

Department of Biological Sciences, National University of Singapore, Block S2, Science Drive 4, Singapore 117543.
botyhh@leonis.nus.sg

        Gamma irradiation of somatic embryos of cassava variety PRC 60a was carried out with the objectives of altering the level of cyanogenic glucoside and starch content it’s quality. Plantlets were raised from 20 different mutant lines and subsequently transferred to the field. No significant decrease in leaf or root linamarin content was observed in any of the mutant lines. Two mutant lines, however, showed either reduced or no storage root formation. X-ray diffraction studies revealed altered starch pattern for the roots of mutant line S9. This was confirmed to be a result of decreased amylose content in the total starch composition. Cytological and flow cytometry studies of S9 plants did not detect any chromosomal aberrations or ploidy differences. Leaf protein profile from SDS PAGE, however, showed differences compared to the control plant. The cDNA libraries were constructed for both mutants as well as control plants to further study the genetic differences. It would be useful to understand the basic biochemical and genetic regulatory mechanisms behind the photosynthetic assimilate accumulation and starch biosynthesis in the storage roots of cassava.