Low nitrate alleviates iron deficiency through regulating iron
homeostasis in apple
Abstract
Iron (Fe) is an essential element for plant growth, development, and
metabolism. Due to its lack of solubility and low bioavailability in
soil, Fe levels are usually far below the optimum amount for most
plants’ growth and development. In apple production, excessive use of
nitrogen fertilizer may cause iron chlorosis symptoms in the newly
growing leaves, but the regulatory mechanism is unclear. In this study,
it was found that low nitrate (NO3-, LN) application could alleviate the
symptoms of Fe deficiency, LN treatment promoted lower the rhizosphere
pH, which was beneficial for root Fe acquisition, meanwhile, LN
treatment increased citrate and abscisic acid (ABA) accumulation in
root, which promoted Fe transport from root to shoot and maintained Fe
homeostasis. Moreover, RNA-Seq and qRT-PCR analysis showed that nitrate
application caused differential expression of genes that were related to
Fe uptake and transport as well as transcriptional regulators. In
summary, our data reveal that low nitrate alleviated Fe deficiency
through multiple pathway, which exhibits a new option for attenuating Fe
deprivation by regulating the balance between nutrients.