Molecular Cloning And Expression Analysis Of Ferric-chelate Reductase Gene In Malus Xiaojinensis

To acquire iron, many plants reduce Fe (â…¢) to Fe (â…¡) in soil by ferric-chelate reductases, which is an obligatory process for the iron acquisition. Mains xiaojinensis Cheng et Jiang (the first iron-efficient genotype in the genus Mains in the world) can use the iron in the soil efficiently under iron-defficient condition. We choose Malus xiaojinensis as the material, and try to isolate the ferric-chelate reductase gene, and then analyze its expression. The results are as following:(1)Ferric-chelate reductase activity was increased with the enhancement of the treatment time under iron-deficiency stress in roots of Mains xiaojinensis.(2)Degenerate primers were designed according to conserved sequence of DRYLRFRLQ and SVEGPYGPA, and the cDNA fragment of the gene was isolated, which was nominated as MxFrol. The sequence is 1500bp in length. It has 86% and 99% identities to the Fro2 gene of Arabidopsis thaliana and Frol of pea respectively. MxFrol has LQWHPFT (FAD-binding site), EGPYGP (NADPH-binding site) domains and heme-binding histidine residuces.(3)Southern blot was performed and indicated that MxFrol has only one single copy in the genome of Malus xiaojinensis.(4)Expression patterns of MxFrol in roots and leaves of Malus xiaojinensis were studied by Northern blot. Expression of MxFrol was detectable in both roots and leaves under normal or iron-deficient conditions. Its expression was induced by iron-deficiency stress in roots, but no significant expression difference was detectable in leaves, which suggested the transcription of MxFrol is regulated by different control mechanisms.