Disease relevance of GA1

• In Escherichia coli cells that express both the Arabidopsis GA1 gene and the Erwinia uredovora gene encoding GGPP synthase, CPP was accumulated [1].
• Recombinant expression in Escherichia coli demonstrated that the product of the Le cDNA was a gibberellin 3 beta-hydroxylase that is able to convert GA20 to the bioactive GA1 [2].

High impact information on GA1

• In transgenic Arabidopsis plants overexpressing P16, there was a severe reduction in the amounts of C20-GA intermediates, accumulation of large amounts of inactive GA25 and GA17, a reduction in GA4 content, and a small increase in GA1 [3].
• A decreased feedback of GA possibly causes an induction of GA biosynthesis based upon the expression of genes encoding copalyl diphosphate synthase (CPS; GA1) and GA 2-oxidase (AtGA2ox1) [4].
• These genes encode the enzymes ent-copalyl diphosphate synthase (CPS) and ent-kaurene synthase, which catalyze the first two committed steps in GA biosynthesis [5].
• These pathways are represented by the genes CO, FCA, and GA1, which act in the long-day, autonomous, and gibberellin pathways, respectively [6].
• When plants were transferred from SD to LD conditions there was a slight decrease in the level of GA53 and an increase in the levels of C19-GAs, GA9, GA20, GA1, and GA8, indicating that GA 20-oxidase activity is stimulated in LD conditions [7].

Biological context of GA1

• Here we showed that expression of GA1 cDNA driven by the 2.4 kb 5'-upstream sequence plus the GA1 genomic coding region into the third exon was able to rescue the gal-3 mutant phenotype [8].
• However, because KSA activity is so low that it is only measurable in Arabidopsis siliques, GA1 promoter-GUS reporter gene fusions and quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) were used to examine the expression pattern of GA1 [9].
• To assess how up-regulation of early steps affects the biosynthetic pathway overall, we have examined transgenic Arabidopsis plants that overexpress either AtCPS or AtKS or both [5].

Associations of GA1 with chemical compounds

• This result indicates that the GA1 gene encodes the enzyme ent-kaurene synthetase A, which catalyzes the conversion of GGPP to CPP [1].
• Overall, GA1 and GA4 levels decreased and abscisic acid levels increased compared with wild-type plants [10].
• The Arabidopsis GA1 gene encodes copalyl diphosphate synthase, which catalyzes the first committed step in the gibberellin biosynthetic pathway [8].
• Together, the data suggest that the developmental defects in the ms33 mutant are unrelated to ABA levels, but may be causally associated with reduced levels of IAA, GA1 and GA4, compared to WT flowers [11].
• The relative activity of GAs for promoting germination of uniconazole-treated seeds was GA4 > GA1 = GA9 > GA20 [12].

Other interactions of GA1

• Eight of them are members of the early-13-hydroxylation pathway (GA53, GA44, GA19, GA17, GA20, GA1, GA29, and GA8), six are members of the early-3-hydroxylation pathway (GA37, GA27, GA36, GA13, GA4, and GA34), and the remaining six are members of the non-3,13-hydroxylation pathway (GA12, GA15, GA24, GA25, GA9, and GA51) [13].

References