Abstract
Iron (Fe) deficiency in plants hinders growth and yield. Thus, this study aims to elucidate the responses and molecular characterization of genes in Fe-deficient sunflower. The study was conducted on 14 days-old sunflower plants cultivated in hydroponic culture under Fe-sufficient and Fe-deficient conditions. The Fe-starved sunflower showed substantial decrease in plant biomass, SPAD score, quantum yield efficiency of PSII (Fv/Fm), photosynthetic performance index (Pi_ABS). Further, Fe shortage reduced Fe and Zn concentrations in roots and shoots, accompanied by a marked decrease of HaNramp1 and HaZIP1 expression in roots, suggesting the association of Zn status contributing to photosynthetic inefficiency in sunflower. The ferric chelate reductase (FCR) activity, along with HaFRO2 and HaIRT1 transcripts, were constitutively expressed, suggesting that sunflower plants can regulate FCR activity, although the lack of bioavailable Fe in the rhizosphere strongly corresponds to the limited Fe uptake in sunflower. The substantial increase of proton extrusion in roots and the localization of Fe-related genes in the plasma membrane are also evident in sunflower as common responses to Fe-deficiency by this Strategy I plant species. Analysis showed that three motifs of Fe-related proteins were linked to the ZIP zinc transporter. The interactome map revealed the close partnership of these Fe-related genes in addition to FRU gene encoding putative transcription factor linked to Fe uptake response. The cis-regulatory analysis of promoter suggested the involvement of auxin, salicylic acid, and methyl jasmonate-responsive elements in the regulatory process in response to Fe deficiency. These findings may be beneficial to develop Fe-efficient sunflower plants through breeding or genome editing approaches.
Highlights
Iron (Fe) deficiency in plants hinders growth and yield
Along with the visual evidence, root and shoot morphological features significantly decreased owing to Fedeficiency in the hydroponic solution compared to Fe-sufficient sunflower plants (Fig. 1a–e)
The parameters associated with photosynthesis, such as SPAD score, Fv/Fm ratio, and Pi_ABS in young leaves, significantly declined due to Fe depletion relative to Fe-sufficient sunflower plants (Fig. 1f–h)
Summary
Iron (Fe) deficiency in plants hinders growth and yield. this study aims to elucidate the responses and molecular characterization of genes in Fe-deficient sunflower. The substantial increase of proton extrusion in roots and the localization of Fe-related genes in the plasma membrane are evident in sunflower as common responses to Fe-deficiency by this Strategy I plant species. Analysis showed that three motifs of Fe-related proteins were linked to the ZIP zinc transporter. The cis-regulatory analysis of promoter suggested the involvement of auxin, salicylic acid, and methyl jasmonate-responsive elements in the regulatory process in response to Fe deficiency These findings may be beneficial to develop Fe-efficient sunflower plants through breeding or genome editing approaches. In Strategy-I plants, ferric chelate reductase (FCR) is an enzyme that converts ferric ion to ferrous in roots to make existing Fe a vailable[9] This FCR activity and the upregulation of its candidate gene (FRO) have been mainly reported to confer Fe-deficiency tolerance in many dicot plants[5,10]. We further performed in silico analysis of Fe-related genes of sunflower to interpret the motifs, regulatory networks, and association of genes linked to Fe-deficiency
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