Biology subjects

Assuncao, A. G.

Publications and source records attributed to Assuncao, A. G..

3 recordsLinked to original sources

bioRxiv2025

Point mutation in sensor triples zinc levels in Sorghum bicolor

Zinc (Zn) deficiency is widespread in agricultural soils and it is also a common nutritional problem in humans. We previously discovered a Zn Sensor Motif (ZSM) in the Arabidopsis F-bZIP transcription factors, bZIP19 and bZIP23, which impacts the concentration of Zn in Arabidopsis plants. Sorghum (Sorghum bicolor (L.) Moench) is one of the most important cereals crops worldwide and here, using a large-scale sorghum mutant library, we report the identification of variants with a ZSM point mutation. We show that a cysteine substitution in the ZSM of the sorghum bZIP19/23 homolog causes a three-fold increase in Zn levels in sorghum seeds with no visible developmental penalty. Our work provides the first evidence that modulating the F-bZIP ZSM is a promising strategy for Zn biofortification in crops. This discovery paves the way to generate Zn biofortified crops and alleviate the global problems of Zn deficient soils and Zn malnutrition.

plant biology↗

bioRxiv2025

Expression patterns of Arabidopsis bZIP19 and bZIP23 elucidate their individual contribution to the regulation of the Zn deficiency response

Plants control the availability of nutrients through tightly regulated homeostasis networks. In Arabidopsis thaliana, the transcription factors bZIP19 and bZIP23 regulate the homeostasis of the micronutrient Zn, acting as the key regulators of the Zn deficiency response and as sensors of cellular Zn status. Although there is a degree of functional redundancy between bZIP19 and bZIP23, their individual contributions in this regulatory process are not yet understood. To gain insight on the individual contributions of bZIP19 and bZIP23, we analysed the phenotypes of bzip19, bzip23 and bzip19bzip23 single and double mutants in response to Zn deficiency, and histochemical GUS staining in pbZIP19::GUS and pbZIP23::GUS lines. Analysis of mutant phenotypes indicated unequal redundancy between bZIP19 and bZIP23. Expression of GUS in pbZIP19::GUS was observed in differentiated root tissues including root hairs, in the vascular tissue of hypocotyl, cotyledons and petals, in leaf trichomes and stamen filament. In pbZIP23::GUS, the expression was predominant in root and shoot apical meristems, being also observed in leaves, root vasculature, stamen filament and anthers. In summary, bZIP19 and bZIP23 have different and mostly non-overlapping tissue-specific expression patterns. This may explain the unequal redundancy between bZIP19 and bZIP23 and their evolutionary retention as paralogs.

plant biology↗

bioRxiv2020

The Arabidopsis bZIP19 and bZIP23 transcription factors act as zinc-sensors to control plant zinc status

Zinc (Zn) is an essential micronutrient for plants and animals because of its structural and catalytic roles in many proteins. Zn deficiency affects ca. two billion people, mainly those living on plant-based diets that rely on crops from Zn deficient soils. Plants maintain adequate Zn levels through tightly regulated Zn homeostasis mechanisms, involving Zn uptake, distribution and storage, but it was not known how they sense Zn status. We use in vitro and in planta approaches to show that the Arabidopsis thaliana F-group bZIP transcription factors bZIP19 and bZIP23, which are the central regulators of the Zn deficiency response, act as Zn sensors by binding Zn2+ ions to a Zn sensor motif (ZSM). Deletions or modifications of this ZSM disrupts Zn binding, leading to a constitutive transcriptional Zn deficiency response, which causes a significant increase in plant and seed Zn accumulation. Since the ZSM is highly conserved in F-bZIPs across land plants, the identification of the first plant Zn-sensor will promote new strategies to improve the Zn nutritional quality of plant-derived food and feed, and contribute to tackle the global Zn deficiency health problem.Competing Interest StatementThe authors have declared no competing interest.View Full Text

plant biology↗