Abstract
In plants, sucrose synthase (SUS) enzymes catalyze conversion of sucrose into fructose and UDP-glucose in the presence of UDP. To investigate the impact of overexpression of heterologous SUS on the growth and development of Arabidopsis, we transformed Arabidopsis plants with an overexpression vector containing an aspen SUS gene (PtrSUS1). The genomic PCR confirmed the successful integration of PtrSUS1 transgene in the Arabidopsis genome. PtrSUS1 expression in transgenic Arabidopsis plants was confirmed by RT-PCR. The SUS activity was dramatically increased in all transgenic lines examined. The three selected transgenic PtrSUS1 lines exhibited faster growth and flowered about 10 days earlier compared to untransformed controls, and also possessed 133%, 139%, and 143% SUS activity compared to controls. Both fresh weights and dry biomass yields of the whole plants from these three selected transgenic lines were significantly increased to 125% of the controls. Transgenic PtrSUS1 lines also had a higher tolerance to higher concentration of sucrose which was reflective of the increased SUS activity in transgenic versus wild-type plants. The growth differences between wild-type and transgenic plants, either in root and hypocotyl length or in fresh and dry weight of whole plant, became more pronounced on the media containing higher sucrose concentrations. Taken together, these results showed that the early flowering, faster growth and increased tolerance to higher sucrose in transgenic lines were caused by the genome integration and constitutive expression of the aspen PtrSUS1 gene in transgenic Arabidopsis.
Highlights
Sucrose synthase (SUS) is an important enzyme in carbohydrate metabolism of plants that catalyzes a reverseble reaction of converting sucrose into fructose and UDP-glucose in the presence of UDP
We show the successful integration of aspen sucrose synthase (SUS) gene (PtrSUS1) in Arabidopsis genome by genomic PCR, overexpression of PtrSUS1 genes in Arabidopsis through RT-PCR, and increased SUS enzyme activities in transgenic plants, suggesting that the observed faster growth during early developmental stages and early flowering in transgenic lines were caused by the integration and overexpression of the aspen SUS gene in the Arabidopsis genome
We wanted to examine the effect of the PtrSUS1 overexpression on growth and development of transgenic Arabidopsis plants
Summary
Sucrose synthase (SUS) is an important enzyme in carbohydrate metabolism of plants that catalyzes a reverseble reaction of converting sucrose into fructose and UDP-glucose in the presence of UDP. SUS gene expression was dramatically reduced in transgenic cotton plants expressing a SUS cosuppression construct, which caused the reduced number of fiber initiations and reduced fiber length, and induced numerous collapsed fiber cells, and even resulted in the failure of setting of seeds in some lines [31]. These results supported a specific role for SUS during fiber initiation and elongation in cotton. We show the successful integration of aspen SUS gene (PtrSUS1) in Arabidopsis genome by genomic PCR, overexpression of PtrSUS1 genes in Arabidopsis through RT-PCR, and increased SUS enzyme activities in transgenic plants, suggesting that the observed faster growth during early developmental stages and early flowering in transgenic lines were caused by the integration and overexpression of the aspen SUS gene in the Arabidopsis genome
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