Control of vitamin C content of vegetables by gene engeneering techniques.

cDNA sequence analysis of L-galactonolactone dehydrogenase (GLDHase) from sweet potato：N-terminal partial sequences of 4 internal polypeptides generated by partial digestion of GLDH-aseV8 protease were determined The clone encoded a polypeptide of 581 amino acid residues with a66kDa. The deduced amino acid sequence showed 77% identity with that ofcauliflower gldhase,and significant homology to that of GLO (22% identity) from rat.1. Analysis of trangenic ato andtomato with the gene for L-gulonolactone oxidase (GLO)：L-gulonolactone oxidase (GLO) which catalyzes the last step of ascorbic acid (AsA) biosynthesis inanimals oxidizes L-galactonolactonea precursor of AsA in plants and yeast. We introduced a rat GLO gene to potato and tomato under thecontrol of CaMV 35s promoter to elucidate whether the expression of GLO gene was confirmed by PCRusing specific primers. GLO activity was detected in several transformants of potato and tobacco.Some of t…More ransgenic potato and tomato with GLO activity contained higher levels of AsA than thatin wild type.2. Sense and antisense expression of ascorbate oxidase (AAO) gene in tobacco plants.效果on ascorbate levels in tobacco leaves：introduced tobacco genes with a sense and an antisense construct of the AAO gene under control ofthe constitutive CaMV 35s promoter to elucidate the function of AAO gene under control of theconstitutive CaMV 35s promoter to elucidate the function of AAO. All of sense transformantD2o had higher levels of ao - mrna and lower levels of AsA than those in wild type. Threeantisense T - D2o plants had high levels of AsAalthough ao - mrna levels in all antisense T - D2o plants much low compared with those inwild type. All T - d -progenies of self-polinated sense T - D2o - D2 plants gown in the presenceKanamycin had high levels of ao - mrna and ao -protein. AsA content in 5 antisenseD21 D2-progenies higher than in wild type. Growth rate of several antisenseD21 -progenies with high AsA content was higher than that of sense D21 -progenies. Theseresults suggest that antisense expression of AAO in vegetables may be useful for breedingvegetables containing high levels of asia . gnomic Southern analysis suggested that GLDHase gene existsas a single copy in the genome of sweet potato. Less

3. cDNA sequence analysis of L-galactonolactone dehydrogenase (GLDHase) from sweet potato : N-terminal partial sequences of 4 internal polypeptides generated by partial digestion of GLDH-ase with V8 protease were determined. The clone encoded a polypeptide of 581 amino acid residues with a molecular mass of 66kDa. The deduced amino acid sequence showed 77% identity with that of cauliflower GLDHase, and significant homology to that of GLO (22% identity) from rat.1. Analysis of trangenic potato and tomato with the gene for L-gulonolactone oxidase (GLO) : L-gulonolactone oxidase (GLO) which catalyzes the last step of ascorbic acid (AsA) biosynthesis in animals oxidizes L-galactonolactone, a precursor of AsA in plants and yeast. We introduced a rat GLO gene to potato and tomato under the control of CaMV 35S promoter to elucidate whether the expression of GLO gene was confirmed by PCR using specific primers. GLO activity was detected in several transformants of potato and tobacco. Some of t … More ransgenic potato and tomato with GLO activity contained higher levels of AsA than that in wild type.2. Sense and antisense expression of ascorbate oxidase (AAO) gene in tobacco plants. Effect on ascorbate levels in tobacco leaves : We introduced tobacco genes with a sense and an antisense construct of the AAO gene under control of the constitutive CaMV 35S promoter to elucidate the function of AAO gene under control of the constitutive CaMV 35S promoter to elucidate the function of AAO. All of sense transformant (TィイD2oィエD2) had higher levels of AAO-mRNA and lower levels of AsA than those in wild type. Three antisense TィイD2oィエD2 plants had high levels of AsA, although AAO-mRNA levels in all antisense TィイD2oィエD2 plants were much low compared with those in wild type. All TィイD21ィエD2-progenies of self-polinated sense TィイD2oィエD2 plants gown in the presence of Kanamycin had high levels of AAO-mRNA and AAO-protein. AsA content in 5 antisense TィイD21ィエD2-progenies were higher than in wild type. Growth rate of several antisense TィイD21ィエD2-progenies with high AsA content was higher than that of sense TィイD21ィエD2-progenies. These results suggest that antisense expression of AAO in vegetables may be useful for breeding vegetables containing high levels of AsA.Gnomic Southern analysis suggested that GLDHase gene exists as a single copy in the genome of sweet potato. Less