| Summary: | Glutamine synthetase (GS) plays a fundamental
role in nitrogen metabolism in higher plants. Three BnGS
genes have first been isolated: one gene encoding plastid
GS (BnGS2) and two encoding cytosolic GS (BnGS1-1 and
BnGS1-2) in ramie. Based on a sequence analysis and
phylogenetic study, three BnGS sequences were classified
into three distinct sub-families. The phylogenetic analysis
showed that BnGS2 and BnGS1-2 were closely related
to those of legumes, alfalfa (Medicago sativa), soybean
(Glycine max) and bean (Phaseolus vulgaris). The BnGS
gene expression patterns revealed that each gene exhibited
similar organ specificity, but distinct transcript intensity
during different vegetative processes. The relatively
abundant expression of BnGS1-1 and BnGS2 at specific
organs during different vegetative processes indicates that
they have critical roles in nitrogen uptake and assimilation
relating to forage and growth characteristics. The BnGS1-2
mRNA levels were remarkably upregulated in the
phloem, xylem and stems during the fiber development
stage, suggesting a correlation with fiber development.
Therefore, the non-overlapping transcript intensity of
BnGS genes in different tissues regulates ramie growth
and development during different vegetative processes.
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