Interdependent iron and phosphorus availability controls photosynthesis through retrograde signaling

Abstract

Iron deficiency hampers photosynthesis and is associated with chlorosis. We recently showed that iron deficiency-induced chlorosis depends on phosphorus availability. How plants integrate these cues to control chlorophyll accumulation is unknown. Here, we show that iron limitation downregulates photosynthesis genes in a phosphorus-dependent manner. Using transcriptomics and genome-wide association analysis, we identify two genes, PHT4;4 encoding a chloroplastic ascorbate transporter and bZIP58, encoding a nuclear transcription factor, which prevent the downregulation of photosynthesis genes leading to the stay-green phenotype under iron-phosphorus deficiency. Joint limitation of these nutrients induces ascorbate accumulation by activating expression of an ascorbate biosynthesis gene, VTC4, which requires bZIP58. Furthermore, we demonstrate that chloroplastic ascorbate transport prevents the downregulation of photosynthesis genes under iron-phosphorus combined deficiency through modulation of ROS homeostasis. Our study uncovers a ROS-mediated chloroplastic retrograde signaling pathway to adapt photosynthesis to nutrient availability.

Tandem application of endophytic fungus Serendipita indica and phosphorus synergistically recuperate arsenic induced stress in rice

“… Nam et al (2021) provided evidence regarding Fe deficiency induced ROS generation as well as chlorosis that becomes more pronounced in the presence of phosphorus rather than its absence, which explains the improved photosynthetic capability and overall growth of plants in this study under S.i + As + P treatment as As hinders the uptake of Fe ( Mousavi et al, 2020 ); neither the availability of P alone compensate for Fe deficit, nor does it represent a guarantee of counterbalancing As toxicity ( Begum et al, 2008 ; Abbasi et al, 2021 ). Availability of P is, tacitly assumed to be, crucial for the concentrations of elements that are imperative for metabolic processes associated with photosynthesis, biomass growth and yield formation, such as Mg ( Weih et al, 2021 ); plants colonized by S. indica combined with As and P benefitted much more than the ones without its symbiosis (i.e., As + P), not only in terms of nutrient uptake but also in the element concentration of Mg, which is indispensable for the formation of chlorophyll molecule ( Weih et al, 2021 ).…”

CAN OF SPINACH, a novel long non-coding RNA, affects iron deficiency responses in Arabidopsis thaliana

“…6; Liang, 2022). COS also contains two overlapping sites with sequence complementarity for the PHT4;4 gene, which is required for phosphate-deficiency induced inhibition of iron chlorosis (Nam et al, 2021; Fig. 6).…”

“…In this study, we have identified a previously unannotated iron-regulated long non-coding RNA gene that we named CAN OF SPINACH ( COS ). It is possible that previous gene expression studies could have misidentified the genes on the opposite strand (AT1G13608 and/or AT1G13609) as iron-regulated, and that the truly iron-regulated mRNA from the locus is actually the COS lncRNA (Rodríguez-Celma et al, 2013; Naranjo-Arcos et al, 2017; Bastow et al, 2018; Nam et al, 2021; Peixoto et al, 2021). We detected a spliced and an unspliced variant of COS in whole shoots of Arabidopsis, both of which were polyadenylated (Fig.…”

Association mapping uncovers maize ZmbZIP107 regulating root system architecture and lead absorption under lead stress

“…Then, the seedlings with uniform growth were transferred to nutrient solutions (pH = 4.5) with 50 mg/L Pb(NO 3 ) 2 and without Pb(NO 3 ) 2 , respectively ( Chen et al., 2007 ). These rice plants were then grown in a culture room with a photoperiod of 14/10 h (day/night) and a temperature of 28/25 °C for 14 days ( Nam et al., 2021 ). Shoot length (SHL) were measured using a ruler.…”

“…Plant basic leucine zipper (bZIP) transcription factors are a relatively conserved and large gene families. A number of bZIP members have been identified in the plants, animals, and yeasts ( Newman and Keating, 2003 ; Nam et al., 2021 ). Previous studies indicated that the bZIP transcription factors play significant roles as regulators in signal transduction and response to diverse biotic/abiotic stresses, such as drought, cold, heat, ABA, and salt stresses ( Weltmeier et al., 2006 ; Hossain et al., 2010 ; Liu et al., 2014 ; Li et al., 2020b ).…”