PGPR-induced regulation of Zn and Fe transporters in wheat (Triticum aestivum L.) uncovered through integrated genome-wide analysis and functional validation.
TL;DR
Overall, the results show that PGPR modulate metal‑transporter gene networks and improve micronutrient biofortification in wheat, providing a genotype‑responsive and sustainable approach to address micronutrient deficiency.
Abstract
Zinc (Zn) and iron (Fe) deficiencies affect more than two billion people globally, particularly in cereal-dependent regions where wheat, despite its high consumption, provides inadequate micronutrient levels. Conventional interventions such as genetic modification and mineral supplementation remain costly, unevenly accessible, and insufficient for large-scale nutritional improvement. Agronomic biofortification using plant growth-promoting rhizobacteria (PGPR) offers a promising yet underexplored alternative, especially for regulating metal homeostasis genes in wheat. This research integrates multi-season field trials of Zn-biofortified Akbar-19 and the local cultivar Khaista-17, conducted under reduced fertilizer conditions with PGPR consortia. Afterwards, genome-wide analyses including phylogenetic relationships, promoter elements, gene interaction networks, expression profiles, and conserved domains/motifs of the TaNAS (19 genes), TaNAAT (6), TaDMAS (3), and TaVIT (31) gene families was performed. This was followed by transcriptional expression (qPCR) of six candidate genes in wheat grown under hydroponic Zn/Fe stress in the presence of PGPR. Field evaluation showed that PGPR inoculation boosted yield by 15-18% and increased grain Zn/Fe by 15-20% in Akbar-19 and 25-28% in Khaista-17, consistently outperforming fertilizer-only controls across both seasons. The genome-wide analyses exhibited the phylogenetic relationship of wheat TaDMAS, TaNAAT, and TaNAS genes with barley, while TaVIT and TaVTL genes with rice and maize. Promoter analyses of these genes showed an enrichment of stress-responsive cis-elements, such as IDE1/2, ZDRE1/2, IRO2-binding sites, and metal-responsive elements suggesting coordinated regulation of micronutrient chelation, uptake, and homeostasis. qPCR results confirmed PGPR-induced upregulation of NAS1, NAS6, NAS9, NAAT2, DMAS1, and VIT2 under Zn/Fe stress, with stronger induction in Khaista-17. Overall, the results show that PGPR modulate metal‑transporter gene networks and improve micronutrient biofortification in wheat, providing a genotype‑responsive and sustainable approach to address micronutrient deficiency.