Revealing the molecular basis regulating the iron deficiency response in quinoa seedlings by physio-biochemical and gene expression profiling analyses

Background and aimsImproving iron utilization efficiency in crops is of great importance to food security and sustainable agricultural development. Quinoa (Chenopodium quinoa Willd.) is a high-iron accumulation crop; however, the molecular mechanisms underlying iron accumulation and iron deficiency response in quinoa are unclear.MethodsWe investigated the molecular basis of the iron deficiency response in quinoa through physio-biochemical and transcriptome analysis using the methods of iron depletion and resupply.ResultsIron depletion inhibits photosynthesis but does not cause obvious oxidative damage in quinoa. Iron resupply generally induces the expression of genes associated with sugar metabolism and primary nitrogen metabolism in roots. The expression of iron-responsive transcription factors, including FIT, BTS and bHLH101, as well as the metal transporters MTP and NRAMP, is induced under iron depletion and continues to be expressed after 6 h of iron resupply. Iron depletion increases the levels of cytokinin, ABA, SA and ethylene precursor ACC but decreases JA levels. The contents of cytokinin and ACC gradually recovered after 6 h of iron resupply, but the ABA content did not change significantly; in contrast, the JA content further decreased. Iron depletion markedly induces DELLA gene expression. Iron depletion does not change the auxin level in roots, but it inhibits the auxin pathway.ConclusionThese results indicated that the iron deficiency response is tightly modulated by phytohormone signaling. This study elucidates the regulatory network of the iron deficiency response and provides a theoretical basis for further exploring the molecular mechanism of high-iron accumulation in quinoa.