Auxin Signaling is Involved in Iron Deficiency-induced Photosynthetic Inhibition and Shoot Growth Defect in Rice (Oryza sativa L.)

摘要

Iron deficiency is one of the most serious nutrient limiting factors that affect rice plant growth and photosynthesis. Several phytohormones, including auxin, participate in iron uptake and homeostasis. However, how auxin signaling is involved in iron deficiency-induced inhibition of shoot growth and photosynthetic efficiency is largely unknown. The Nipponbare (NIP) seedlings displayed typical chlorotic symptoms, biomass reduction and photosynthesis depression when subjected to iron deficiency. We measured the soluble Fe content in the shoots under different conditions. The soluble Fe content in the shoots under Fe deficiency was increased by 1-naphthoxyaceticacids (1-NOA) treatment and was decreased by 1-naphthaleneacetic acid (NAA) treatment. Blocking (1-NOA treatment) or enhancement (NAA treatment) of auxin signaling also affects photosynthetic parameters under Fe deficiency conditions. Furthermore, rice microarray data (GSE17245 and GSE39429) were used to analyze the relationship between iron deficiency responses and auxin signaling in shoots. Most iron deficiency response gene expression levels in the shoots increased under exogenous auxin treatment, and most auxin early response gene expression levels responded to iron deficiency. It suggested that there is a crosstalk between iron deficiency signaling and auxin signaling. Our results indicated that iron deciency-induced growth inhibition and photosynthesis depression were mediated by systemic auxin signaling.