Cloning and functional analysis of the peanut iron transporter AhIRT1 during iron deficiency stress and intercropping with maize

In previous research, iron-deficiency symptoms in peanut (Arachis hypgaea) were alleviated during anthesis by intercropping with maize. This benefit was associated with increased phytosiderophore secretion by maize and increased Fe(III)-chelate reductase activity by peanut. In the present study, we isolated the full-length cDNA of AhIRT1 (iron-regulated transporter 1) from peanut and characterized how iron deficiency and intercropping affected its iron-transporting ability. Functional complementation with AhIRT1 restored normal growth of the yeast mutant fet3fet4 (defective in both high- and low-affinity iron-uptake systems) under iron-deficiency conditions. Based on transient expression analysis, AhIRT1 was determined to be a membrane protein, which was consistent with a function in iron uptake. In peanut, transcript levels of AhIRT1 increased in both root and shoot under iron-deficiency conditions. In a pot experiment, AhIRT1 transcript levels in intercropped peanut were 10 times greater during anthesis than pre-anthesis, and transcript levels during anthesis were 40% greater in intercropped than in monocropped peanut.