Expression of FER-Like Iron Deficiency-Induced Transcription Factor (FIT) in Populus tremula L.

FER-like iron deficiency-induced transcription factor (FIT), an ortholog of FER (also known as bHLH29, FRU, or FIT1) regulates various iron deficiency inducible genes with known or putative functions in iron homeostasis. Research indicated that FIT interacts with the subgroup Ib of bHLH transcription factor genes to control iron uptake and transport by regulating the expression of FRO2 and IRT1 genes that are key genes regulating ferric reduction and iron transport in plants. In this research, expression of PtFIT gene in Populus tremula ‘Erecta’ was determined in response to iron deficient using quantitative real-time PCR (qPCR). Primers for qPCR were designed based on the putative PtFIT gene sequence that was annotated according to the whole genome sequence of Populus trichocarpa. The putative amino acid sequence analysis suggested that PtFIT gene contains a bHLH domain that shows 91.4% similarity to AtFIT gene. Sequence analysis showed that PtFIT of Populus tremula is identical to the FIT gene in Populus trichocarpa and contains partial bHLH domain. PtFIT highly expressed in roots; however, its expression was rarely detected in leaves. Expression of PtFIT in leaves was inhibited by iron deficiency (no iron or presence of Fe (III)-EDTA) in the first 3 days and then gradually increased after 3 days of iron deficiency treatment. Expression of PtFRO2 and PtIRT1 will be determined to confirm that PtFIT is a regulator of PtFRO2 and PtIRT1 in Populus tremula. The research will help interpret the mechanism of gene regulation in response to iron deficiency and address iron chlorosis in woody species.