Inhibition of Starch Biosynthesis by Antisense Expression of cDNAs Encoding ADP-Glucose Pyrophosphorylase Small Subunit in Sweetpotato

Embryogenic calluses derived from shoot apical meristem explants of sweetpotato were subjected to particle bombardment to generate transgenic plants for antisense expression of cDNAs encoding two different AGPase small subunit (ibAGP1 and ibAGP2). Plants were generated via somatic embryogenesis. PCR and Southern analysis demonstrated that the incorporation of ibAGP1 and ibAGP2 into the genome in an antisense orientation. Immunoblot analysis confirmed reduced levels of AGPase small subunit in transgenic plant leaves. Plants with both ibAGP1 and ibAGP2 produced a lower level of the protein than plants with ibAGP1 alone. Iodine test demonstrated that transgenic plant leaves and storage root accumulated reduced amounts of starch. Iodine staining of leaf tissues indicated that transgenic plants accumulated less amount of starch than control.