Expression of Ferric Chelate Reductase Gene in Citrus junos and Poncirus trifoliate Tissues

摘要

It has been hypothesized that under iron stress high ferric chelate reductase (FCR) activity in the absorptive root of plants tolerant to iron-deficiency will be induced and result in subsequent Fe~(2+) transport across the plasmalemma. The activity of FCR and expression of FCR gene (FRO2) in Citrus junos Sieb. ex Tanaka tolerant to iron-deficiency and Poncirus trifoliata (L.) Raf. susceptible to iron-deficiency were determined to elucidate the physiological difference which causes the different tolerance of the two citrus rootstocks to iron stress. The activity of FCR was detectable in excised roots and was stimulated about 20-times in C. junos and only about 3-times in P. trifoliata under iron deficiency for four weeks. The FR02 of Arabidopsis was used as a probe, the tissue print technique was used to ascertain the expression of the FCR gene in C. junos and P. trifoliata under iron stress. High-level transcripts were observed in the absorptive root, young green stem as well as new leaf of C. junos under iron stress for two weeks, and the transcripts were accumulated only slightly in P. trifoliata at the same time. The results showed that the obvious increase of FCR activity was an important reason for the tolerance of C. junos to iron-deficiency, and the regulation of FCR activity seemed to be at the transcriptional level, and the expression of FRO2 occurred in the root, stem and leaf.