Publicação
Grapevine response to cold - study of starch metabolism in woody tissues
| Resumo: | Grapevine (Vitis vinifera L.) is one of the most important agronomical species in the world, but in the context of the ongoing climate changes, extreme temperatures, high light intensities and water deficit are becoming important threats in many important viticultural areas worldwide. Among these, stress caused by cold has been shown to influence its productivity, metabolism and gene expression, which prompted us to study some molecular mechanisms involved in grapevine response to low temperature. In this regard, cv. Vinhão canes were harvested and incubated at 4 ºC for 7, 14 and 30 days to unravel physiological changes, identify and characterize key genes involved in response to cold. Results showed that starch levels steadily decreased during the incubation period at 4 ºC, and that the expression of the amylolytic gene VvAMY2 increased along time, while the expression of VvBAM5 decreased. Furthermore, HPLC analysis showed an increase in sucrose, fructose and glucose during the incubation at 4 ºC. Additional expression studies of key-genes involved in sugar metabolism showed that the steady-state transcript levels of VvpGT2 and VvSWEET2b transporters as well as VvSusy and VvSPS enzymes increased along time, while the expression of the transporters VvTMT1 and VvSUC27 was downregulated. The VvpGT2 gene was selected for further studies regarding organ specific expression and function. VvpGT2 steady-state transcript levels were high in mature berries and flowers. Following heterologous expression in a mutant yeast (EBY.VW4000) lacking monosaccharide transporters, no VvpGT2 transport activity of fructose, glucose and sucrose could be detected. Raffinose and stachyose levels in the grapevine canes were quantified by HPLC because the metabolism of raffinose has been linked to cold response. Results showed a steadily increase of raffinose levels along incubation at 4 ºC and transcriptional studies also revealed a noticeable increase of the steady-state levels of the galactinol synthase genes VvGolS1 and VvGOLS3 raffinose synthase VvRafS5. |
|---|---|
| Autores principais: | Silva, Tiago Daniel Machado da |
| Assunto: | Abiotic stress qPCR Starch metabolism Sugar transport Vitis vinifera qPCR Metabolismo do amido Stress abiótico Transporte de açúcares Vitis vinifera |
| Ano: | 2019 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | Grapevine (Vitis vinifera L.) is one of the most important agronomical species in the world, but in the context of the ongoing climate changes, extreme temperatures, high light intensities and water deficit are becoming important threats in many important viticultural areas worldwide. Among these, stress caused by cold has been shown to influence its productivity, metabolism and gene expression, which prompted us to study some molecular mechanisms involved in grapevine response to low temperature. In this regard, cv. Vinhão canes were harvested and incubated at 4 ºC for 7, 14 and 30 days to unravel physiological changes, identify and characterize key genes involved in response to cold. Results showed that starch levels steadily decreased during the incubation period at 4 ºC, and that the expression of the amylolytic gene VvAMY2 increased along time, while the expression of VvBAM5 decreased. Furthermore, HPLC analysis showed an increase in sucrose, fructose and glucose during the incubation at 4 ºC. Additional expression studies of key-genes involved in sugar metabolism showed that the steady-state transcript levels of VvpGT2 and VvSWEET2b transporters as well as VvSusy and VvSPS enzymes increased along time, while the expression of the transporters VvTMT1 and VvSUC27 was downregulated. The VvpGT2 gene was selected for further studies regarding organ specific expression and function. VvpGT2 steady-state transcript levels were high in mature berries and flowers. Following heterologous expression in a mutant yeast (EBY.VW4000) lacking monosaccharide transporters, no VvpGT2 transport activity of fructose, glucose and sucrose could be detected. Raffinose and stachyose levels in the grapevine canes were quantified by HPLC because the metabolism of raffinose has been linked to cold response. Results showed a steadily increase of raffinose levels along incubation at 4 ºC and transcriptional studies also revealed a noticeable increase of the steady-state levels of the galactinol synthase genes VvGolS1 and VvGOLS3 raffinose synthase VvRafS5. |
|---|