The 5'UTR-intron of the Gladiolus polyubiquitin promoter GUBQ1 enhances translation efficiency in Gladiolus and Arabidopsis.
BACKGROUND
There are many non-cereal monocots of agronomic, horticultural, and biofuel importance. Successful transformation of these species requires an understanding of factors controlling expression of their genes. Introns have been known to affect both the level and tissue-specific expression of genes in dicots and cereal monocots, but there have been no studies on an intron isolated from a non-cereal monocot. This study characterizes the levels of GUS expression and levels of uidA mRNA that code for β-glucuronidase (GUS) expression in leaves of Gladiolus and Arabidopsis using GUBQ1, a polyubiquitin promoter with a 1.234 kb intron, isolated from the non-cereal monocot Gladiolus, and an intronless version of this promoter.


RESULTS
Gladiolus and Arabidopsis were verified by Southern hybridization to be transformed with the uidA gene that was under control of either the GUBQ1 promoter (1.9 kb), a 5' GUBQ1 promoter missing its 1.234 kb intron (0.68 kb), or the CaMV 35 S promoter. Histochemical staining showed that GUS was expressed throughout leaves and roots of Gladiolus and Arabidopsis with the 1.9 kb GUBQ1 promoter. GUS expression was significantly decreased in Gladiolus and abolished in Arabidopsis when the 5'UTR-intron was absent. In Arabidopsis and Gladiolus, the presence of uidA mRNA was independent of the presence of the 5'UTR-intron. The 5'-UTR intron enhanced translation efficiency for both Gladiolus and Arabidopsis.


CONCLUSIONS
The GUBQ1 promoter directs high levels of GUS expression in young leaves of both Gladiolus and Arabidopsis. The 5'UTR-intron from GUBQ1 resulted in a similar pattern of β-glucuronidase translation efficiency for both species even though the intron resulted in different patterns of uidA mRNA accumulation for each species.
US Department of Agriculture, Floral and Nursery Plants Research Unit, Beltsville, MD 20705-2350, USA.
Kathryn
K
Kamo
Ah-Young
AY
Kim
Se Hee
SH
Park
Young Hee
YH
Joung
D020121:5' Untranslated Regions; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D015870:Gene Expression; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D027621:Iridaceae / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D025821:Polyubiquitin / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D015854:Up-Regulation
D020121:5' Untranslated Regions; D010940:Plant Proteins; D025821:Polyubiquitin; D005966:Glucuronidase