Response of Iron Regulated-transporter Genes (IRT) to Iron Deficiency in Populus tremula L

Iron chlorosis is one of the severe problems in alkaline/calcareous soil, resulting in yield loss and nutrition limitation in plants. Research suggested that iron chlorosis could be caused either by iron deficiency in the environment or disfunction of iron absorption and transportation of plants. As a key transporter of iron, iron regulated-transporter (IRT) genes control iron transportation from the root surface to the leaf where iron is used for synthesis of chlorophyll. In this study, expression of two PtIRT genes (PtIRT1 and PtIRT3) in two phenotypes (PtY, a wild type and PtG, a putative mutant) of Populus tremula ‘Erecta’ responding to iron deficiency was determined using real-time PCR. The PtIRT1 gene highly expressed in roots and its expression was rarely detected in other tissues; however, PtIRT3 expressed in the root, leaf, shoot tip, and stem. In roots, the abundance of PtIRT1 was much more than that of PtIRT3 under iron deficiency condition. Expression of PtIRT1 significantly increased at day 3 and reached its peak at day 6 after iron deficiency treatment. PtIRT3 responded iron deficiency faster than PtIRT1in roots and its expression reached its peak at day 1 and then decreased at day 3 after iron deficiency treatment. Similar expression pattern of PtIRT1and PtIRT3was observed in PtG and PtY; however, the expression level of PtIRT was much higher in PtG than in PtY.