The impact of the overexpression of human UDP-galactose transporter gene hUGT1 in tobacco plants.
When the human UDP-galactose transporter 1 gene (hUGT1) was introduced into tobacco plants, the plants displayed enhanced growth during cultivation, and axillary shoots had an altered determinate growth habit, elongating beyond the primary shoots and having a sympodial growth pattern similar to that observed in tomatoes at a late cultivation stage. The architecture and properties of tissues in hUGT1-transgenic plants were also altered. The leaves had an increase in thickness, due to an increased amount of spongy tissue, and a higher content of chlorophyll a and b; the stems had an increased number of xylem vessels and accumulated lignin and arabinogalactan proteins (AGPs). Some of these characteristics resembled a gibberellin (GA)-responsive phenotype, suggesting involvement of GA. RT-PCR-based analysis of genes involved in GA biosynthesis suggested that the GA biosynthetic pathway was not activated. However, an increase in the proportion of galactose in polysaccharide side chains of AGPs was detected. These results suggested that because of higher UDP-galactose transport from the cytosol to the Golgi apparatus, galactose incorporation into polysaccharide side chains of AGP is involved in the gibberellin response, resulting in morphological and architectural changes.
Center for Gene Science, Hiroshima University, 1-4-2 Kagamiyama, Higashi-Hiroshima, Hiroshima, Japan.
Mohamed Farouk Mohamed
MF
Khalil
Hiroyuki
H
Kajiura
Kazuhito
K
Fujiyama
Kanae
K
Koike
Nobuhiro
N
Ishida
Nobukazu
N
Tanaka
D015153:Blotting, Western; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D015870:Gene Expression; D006801:Humans; D008031:Lignin / Q000378:metabolism; D009004:Monosaccharide Transport Proteins / Q000235:genetics / Q000378:metabolism; D009088:Mucoproteins / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D018547:Plant Stems / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014026:Nicotiana / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D000099237:UDP-Galactose Translocators
D002734:Chlorophyll; D000077194:Chlorophyll A; D008031:Lignin; D009004:Monosaccharide Transport Proteins; D009088:Mucoproteins; D010940:Plant Proteins; D000099237:UDP-Galactose Translocators; C006619:arabinogalactan proteins