Potato with altered starch composition

AM02 potatos synthesize starch that is practically amylose-free and primarily consists of amylopectin.

South America

pAP2

Solanum tuberosum was transformed with a construct containing a fragment of the coding region of the potato granule bound starch synthase (gbss) gene in antisense direction. By introduction of an antisense-sequence the edogeneous gbss gene is silenced post-transcriptionally. This leads to a significant reduced expression of GBSS-protein and therefore an impaired amylose synthesis; the synthesized starch within these potato lines consists almost exclusively of amylopectin.

As a selection marker a mutated version of the gene ahas (acetohydroxy acid synthase (AHAS), acetolactate synthase (ALS)) from Arabidopsis thaliana was choosen. The expression of this gene is controlled by the nos promoter and the ocs terminator from Agrobacterium tumefaciens. The AHAS protein catalyzes the first step of the biosynthesis of the amino acids valine, leucine and isoleucine and a homologous gene can be found in all plants. Unlike the native gene the used mutated version of the AHAS protein cannot be inhibited by the herbicide Imazamox (active ingriedient: sulfonylurea and/or imidazolinone).  

PCR based methods, to be developed on information about the transformation vector.