title: Comparison of ascorbic acid biosynthesis in different tissues of three non-heading Chinese cabbage cultivars.
abstract: Ascorbic acid (L-AsA) is an important antioxidant in plants and humans. Vegetables are one of the main sources of ascorbic acid for humans. For instance, non-heading Chinese cabbage (Brassica campestris ssp. chinensis Makino) is considered as one of the most important vegetables in south China. To elucidate the mechanism by which AsA accumulates, we systematically investigated the expression profiles of D-mannose/L-galactose pathway-related genes. We also investigated the recycling-related genes and AsA contents in different tissues of three non-heading Chinese cabbage cultivars, 'Suzhouqing', 'Wutacai' and 'Erqing' containing different amounts of AsA. Our results showed that six genes [D-mannose-6-phosphate isomerase 1 (PMI1), GDP-L-galactose phosphorylase 1 (GGP1), GGP2, GGP4, GDP-mannose-3', 5'-epimerase1 (GME1), and GME2] were expressed at high level and ascorbate oxidase (AAO) was expressed at low level. This expression pattern contributes, at least partially, to higher AsA accumulation in the leaves and petioles than in the roots. Eight genes (PMI1, GME, GGP, L-galactose-1-phosphate phosphatase, L-galactose dehydrogenase, L-galactono-1, 4-lactone dehydrogenase, monodehydroascorbate reductase 1, and glutathione reductase1) were also expressed at high level; AAO and ascorbate peroxidase (APX) were expressed at low level. This expression pattern may similarly contribute to higher AsA accumulation in 'Wutacai' and 'Suzhouqing' than in 'Erqing'. Therefore, the high expression levels of PMI, GME, and GGP and the low expression level of AAO contributed to the high AsA accumulation in non-heading Chinese cabbage.
authors.affiliation: Horticultural Department, Nanjing Agricultural University, Nanjing 210095, China; State Key Laboratory of Crop Genetics & Germplasm Enhancement, Nanjing 210095, China; Key Laboratory of Southern Vegetable Crop Genetic Improvement, Ministry of Agriculture, Nanjing 210095, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ren
authors.forename: Zhongwen
authors.initials: Z
authors.lastname: Chen
authors.forename: Weike
authors.initials: W
authors.lastname: Duan
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Song
authors.forename: Tongkun
authors.initials: T
authors.lastname: Liu
authors.forename: Jianjun
authors.initials: J
authors.lastname: Wang
authors.forename: Xilin
authors.initials: X
authors.lastname: Hou
authors.forename: Ying
authors.initials: Y
authors.lastname: Li
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001205:Ascorbic Acid / Q000096:biosynthesis* / Q000235:genetics; D001937:Brassica / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002681:China; D004032:Diet; D005690:Galactose / Q000378:metabolism; D015870:Gene Expression; D017343:Genes, Plant; D006801:Humans; D008358:Mannose / Q000378:metabolism; D018515:Plant Leaves; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots; D018514:Plant Structures / Q000378:metabolism*; D013045:Species Specificity
chemical_list: D000975:Antioxidants; D010940:Plant Proteins; D008358:Mannose; D001205:Ascorbic Acid; D005690:Galactose
keywords: AAO; APX; AsA; Ascorbate recycling processes; Ascorbic acid; Ascorbic acid biosynthesis; DHAR; GDH; GDP-l-galactose phosphorylase; GDP-mannose pyrophosphorylase (mannose-1-phosphateguanyltransferase); GDP-mannose-3′, 5′-epimerase; GGP; GLDH; GME; GMP; GPP; GR; MDHAR; MI; Non-heading Chinese cabbage; PMI; PMM; T-AsA; ascorbate oxidase; ascorbate peroxidase; ascorbic acid (vitamin C); d-GalUA; d-Glu; d-GluA; d-Mannose/l-galactose pathway; d-galacturonic acid; d-glucose; d-glucuronic acid; d-mannose-6-phosphate isomerase; dehydroascorbate reductase; glutathione reductase; l-Gal; l-GalL; l-GulL; l-galactono-1,4-lactone; l-galactono-1,4-lactone dehydrogenase; l-galactose; l-galactose dehydrogenase; l-galactose-1-phosphate phosphatase; l-gulono-1,4-lactone; monodehydroascorbate reductase; myo-inositol; phosphomannomutase; qRT-PCR; quantitative real-time PCR; total AsA