Cloning and expression analysis of a nitrate reductase gene related to somatic embryogenesis in Gossypium hirsutum

摘要

Nitrate reductase is a key enzyme in the overall process of nitrate assimilation by plants. A nitrate reductase(NR)gene related to somatic embryogenesis was firstly cloned fromGossypium hirsutum. Sequence alignment shows that the GhNR is closest with Tilia platyphyllos NR gene. The expression of GhNR was investigated using semi-quantitative RT-PCR in nonembryogenic calli, embryogenic calli and somatic embryoids which showed thatthe expression level of GhNR was higher in embryogenic calli and somatic embryoids than in nonembryogenic calli. Besides, the expression of GhNR gene was verified by transformation inE. coliBL21 (DE3) strain with the recombinant expression vector pET-32a. NR activity assay showed that the crude GhNR protein had obvious activity to KNO3substrate. The results implied that NR has a critical function in the assimilation of nitrogen in cotton somatic embryo germination.