Comparative Transcriptome Analysis of Iron and Zinc Deficiency in Maize (Zea mays L.).

Mallana Gowdra Mallikarjuna,Soma Sunder Marla,Rinku Sharma,Hari Shanker Gupta,Jayant S Bhat,Kanchikeri Math Manjaiah,Ar Rao,Firoz Hossain,Kaliyugam Shiriga,Nepolean Thirunavukkarasu,Amitha Cr Mithra

doi:10.3390/plants9121812

Abstract

Globally, one-third of the population is affected by iron (Fe) and zinc (Zn) deficiency, which is severe in developing and underdeveloped countries where cereal-based diets predominate. The genetic biofortification approach is the most sustainable and one of the cost-effective ways to address Fe and Zn malnutrition. Maize is a major source of nutrition in sub-Saharan Africa, South Asia and Latin America. Understanding systems’ biology and the identification of genes involved in Fe and Zn homeostasis facilitate the development of Fe- and Zn-enriched maize. We conducted a genome-wide transcriptome assay in maize inbred SKV616, under –Zn, –Fe and –Fe–Zn stresses. The results revealed the differential expression of several genes related to the mugineic acid pathway, metal transporters, photosynthesis, phytohormone and carbohydrate metabolism. We report here Fe and Zn deficiency-mediated changes in the transcriptome, root length, stomatal conductance, transpiration rate and reduced rate of photosynthesis. Furthermore, the presence of multiple regulatory elements and/or the co-factor nature of Fe and Zn in enzymes indicate their association with the differential expression and opposite regulation of several key gene(s). The differentially expressed candidate genes in the present investigation would help in breeding for Fe and Zn efficient and kernel Fe- and Zn-rich maize cultivars through gene editing, transgenics and molecular breeding.

Highlights

Iron (Fe) and zinc (Zn) are essential elements for all living organisms, including plants and animals
The typical stress symptoms were prominent among the stress treatments at 10 days after transplanting (DAT) (Figure 1)
The Fe and Zn deficiencies altered the morpho-physiological and molecular responses through the differential expression of genes associated with phytohormonal regulations, transporters and photosynthesis

Summary

Introduction

Iron (Fe) and zinc (Zn) are essential elements for all living organisms, including plants and animals. Plants 2020, 9, 1812 the economic yield in crops and thereafter manifests in the form of micronutrient malnutrition in humans [3]. The uptake of Fe ions in plants occurs through two important strategies viz., the reduction-based strategy (strategy-I) and chelation-based strategy (strategy-II). The strategy-I is present in all the plants except those from the Poaceae family. Under Fe deficiency, the strategy-I plants release the protons into the rhizosphere by H+ -ATPases and makes the Fe more soluble by lowering the soil pH. Plants of Poaceae family mostly follow a mugineic acid (MA) pathway-based chelation strategy (Strategy-II) to uptake the Fe from soil [5]. The grass plants release derivatives of deoxymugineic acid (DMA) called phytosiderophores (PS) which make the complex with the ferric ions (Fe3+ ). In maize, the recent finding showed the presence of strategy-I genes for the uptake of Fe [12]

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Discussion

Conclusion