Effect of nitrogen supply on nitrogen metabolism in the citrus cultivar 'Huangguogan'.

摘要: Nitrogen metabolism in citrus has received increased attention due to its effects on plant growth and productivity. However, little is known about the of nitrogen fertilization young trees cultivar 'Huangguogan' (Citrus reticulata × Citrus sinensis). Here, genes encoding nitrate reductase (NR), nitrite (NiR), glutamine synthetase (GS), glutamate dehydrogenase (GDH), asparagine (AS), represented as HgNR, HgNiR, HgGS, HgGDH, HgAS, respectively, were cloned from Huangguogan. Deduced protein sequences analyzed proteins confirmed be localized their respective cellular organelles. Moreover, pot-cultured seedlings fertilized with 0 (N1), 1.36 (N2), 1.81 (N3), 2.26 (N4), or 2.72 (N5) kg N/year, for 12 months. Enzyme activity enzyme-gene expression studied roots, leaves, fruits at different stages. Finally, N application rate root activity, leaf N, soluble protein, yield, fruit quality ripening stage measured. The results showed that: 1) HgAS gene products found mainly cytoplasm plasma membrane, while HgGS product was mitochondria. 2) Gene enzyme differed among organs. As permanent direct contact soil we suggest that can used reference determine rate. 3) Yield, quality, enzyme-related considerably lower low than high-N supply. they all inhibited by excess (i.e., kg/year). Therefore, recommend N/year optimal trees.