In vivo Expression of a Cicer arietinum ?-galactosidase in Potato Tubers Leads to a Reduction of the Galactan Side-chains in Cell Wall Pectin
Mart?n S?nchez, Jos? Ignacio | Dopico, Berta | Mu?oz, Francisco J. | Esteban Gallego, Mar?a Roc?o | Oomen, Ronald J. F. J. | Driouich, Azeddine | Vincken, Jean-Paul | Visser, Richard | Labrador, Emilia
We report the generation of Solanum tuberosum transformants expressing Cicer arietinum ?III-Gal. ?III-Gal is a ?-galactosidase able to degrade cell wall pectins during cell wall loosening that occurs prior to cell elongation. cDNA corresponding to the gene encoding this protein was identified among several chickpea ?-galactosidase cDNAs, and named CanBGal-3. CanBGal-3 cDNA was expressed in potato under the control of the granule-bound starch synthase promoter. Three ?III-Gal transformants with varying levels of expression were chosen for further analysis. The transgenic plants displayed no significant altered phenotype compared to the wild type. However, ?-galactanase and ?-galactosidase activities were increased in the transgenic tuber cell walls and this affected the potato tuber pectins. A reduction in the galactosyl content of up to 50% compared to the wild type was observed in the most extreme transformant, indicating a reduction of 1,4-?- galactan side-chains, as revealed by analysis with LM5 specific antibodies. Our results confirm the notion that the pectin-degrading activity of chickpea ?III-Gal reported in vitro also occurs in vivo and in other plants, and confirm the involvement of ?III-Gal in the cell wall autolysis process. An increase in the homogalacturonan content of transgenic tuber cell walls was also observed by Fourier transform infrared spectroscopy (FTIR) analysis.
Показать больше [+] Меньше [-]This work was supported by a grant from the EC (CT97 2224) and a grant from the Direcci?n General de Investigaci?n, Spain (BOS2002?01900).
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