KEY MESSAGE: The IbAGP1 gene of sweet potato ( Ipomoea batatas ) encodes the @entity969 -inducible small subunit of @entity857 - @entity413 pyrophosphorylase. Through expression analysis of 5'-truncations and synthetic forms of the IbAGP1 promoter in transgenic @entity286 , we show that SURE-Like elements and W-box elements of the promoter contribute to the @entity969 inducibility of this gene. Sweet potato (Ipomoea batatas) contains two genes (IbAGP1 and IbAGP2) encoding the catalytically active small subunits of @entity857 - @entity413 pyrophosphorylase, an enzyme with an important role in regulating starch synthesis in higher plants. Previous studies have shown that IbAGP1 is expressed in the storage roots, leaves, and stem tissues of sweet potato, and its transcript is strongly induced by applying @entity969 exogenously to detached leaves. To investigate the tissue-specific expression of the IbAGP1 promoter, a series of 5'-truncated promoters extending from bases -1913, -1598, -1298, -1053, -716, and -286 to base +75 were used to drive the expression of the b-glucuronidase reporter gene (GUS) in @entity286 plants ( @entity286 ). Histochemical and fluorometric GUS assays showed that (1) GUS expression driven by the longest fragment (1989  bp) of the IbAGP1 promoter was detected in vegetative tissues (roots, stems, leaves), (2) fragments extending to -1053 or beyond retained strong GUS expression in roots, stems, and leaves, whereas further 5'-deletions resulted in considerable reduction in GUS activity, and (3) the series of 5'-truncated promoters responded differently to exogenously applied @entity969 . The 1989-bp IbAGP1 promoter contains five sequences (two AATAAAA, one AATAAAAAA, and two AATAAATAAA) that are similar to @entity969 -responsive elements (SURE). These SURE-Like sequences are found at @entity4334 positions -1273, -1239, -681, -610, and -189. Moreover, putative W-box elements are found at positions -1985, -1434, -750, and -578. Synthetic promoters containing tandem repeats of the 4X SURE-Like or 4X W-box upstream from a minimal CaMV35S promoter-GUS fusion showed significant expression in transgenic @entity286 in response to exogenous @entity969 . These results show that SURE-Like elements and W-box elements of the IbAGP1 promoter contribute to the @entity969 inducibility of this gene.

Promoter analysis of the sweet potato XXXX - @entity413 pyrophosphorylase gene IbAGP1 in @entity286 .

@entity286 :: ('4097', 'Species') :: ['Nicotiana tabacum', 'tobacco'] @entity969 :: ('MESH:D013395', 'Chemical') :: ['sucrose'] @entity4334 :: ('D009711', 'Chemical') :: ['nucleotide'] @entity857 :: ('MESH:D000244', 'Chemical') :: ['ADP'] @entity413 :: ('MESH:D005947', 'Chemical') :: ['glucose']
@entity857 :: (MESH:D000244,Chemical) :: ['ADP']
