Biology subjects

Agrwal, K.

Publications and source records attributed to Agrwal, K..

3 recordsLinked to original sources

bioRxiv2025

CRISPR/Cas9 editing of the wheat iron sensor TaHRZ1 confirms its conserved role in iron homeostasis and allocation in grains

Plants rely on specialized sensing systems, including transcriptional regulators, to maintain iron (Fe) homeostasis. Among these, Hemerythrin RING Zinc finger (HRZ) proteins have emerged as key regulators of Fe homeostasis. In this study, six Triticum aestivum (wheat) HRZ homoeologs belonging to TaHRZ1 and TaHRZ2, were identified by BLAST search using rice (Oryza sativa) HRZ sequences and mapped to chromosomes 1 and 3. These encode proteins with conserved N-terminal Hemerythrin (HHE) domains and C-terminal CHY-RING and Zn-ribbon motifs. Phylogenetic analysis grouped these genes into distinct clades, while expression profiling revealed strong root-specific and Fe-responsive expression patterns, indicating roles in nutrient sensing. Functional conservation was demonstrated by complementation of the Arabidopsis thaliana bts-1 mutant, where both wheat genes restored normal Fe regulation. Full-length TaHRZ1 and TaHRZ2 interacted with members of wheat bHLH IVc transcription factors, while truncated versions lacking the RING domain did not, emphasizing their conserved role in protein interactions. CRISPR-Cas9 editing of the conserved HHE3 domain in all the TaHRZ1 homoeologs, coupled with GRF4-GIF1 chimeric protein, achieved 6.4-8.8% regeneration efficiency in wheat. Elemental analysis indicated enhanced Fe loading in the grains of the edited lines, particularly in the scutellum, suggesting improved iron partitioning compared to the wild type. Additionally, qRT-PCR revealed upregulation of TaFIT and TaIRO3, and downregulation of IDEF1 in edited lines, supporting an important regulatory role for TaHRZ1 in Fe homeostasis signalling. These findings position TaHRZ1 as a valuable target for biofortification strategies to enhance Fe content in wheat grains.

plant biology↗

bioRxiv2025

Integrative spatial transcriptomic analysis pinpoints the role of TaMCO3 encoding ferroxidase in wheat root tip iron mobilization

Roots play an critical role in the sensing and absorption of essential minerals from the rhizosphere. Iron (Fe) deficiency, for example, triggers a well-known series of physiological and molecular responses within roots that facilitate uptake, which differs between monocots and dicots. In monocots, little is known about molecular responses that occur within specific root development zones in response to iron deprivation, and how these differences results in overall nutrient uptake. Here, we conducted a transcriptome analysis of wheat root tips under Fe deficiency (-Fe) and performed a comparative transcriptome analysis with the previous datasets generated from the whole root. Gene ontology analysis of differentially expressed genes highlighted the significance of oxidoreductase activity and metal/ion transport in the root tip, which are critical for Fe mobilisation. Interestingly, wheat, an allohexaploid species consisting of three different genomes (A, B, and D) displayed varying gene expression levels arising from the three genomes that contributed to similar molecular functions. Detailed analysis of oxidoreductase function at the root tip revealed multiple multi-copper oxidase (MCO) proteins, such as Fe-responsive TaMCO3, that likely contribute to the overall ferroxidase activity. Detailed characterisation of TaMCO3 shows that it complements the yeast FET3 mutant and rescues the -Fe sensitivity phenotype of Arabidopsis atmco3 mutants by enhancing vascular Fe loading. Transgenic wheat lines overexpressing TaMCO3 exhibited increased root Fe accumulation and improved tolerance to -Fe by augmenting the expression of Fe-mobilizing genes. Our findings highlight the role of spatially resolved gene expression in -Fe responses, suggesting strategies to reprogram cells for improved nutrient stress tolerance.

plant biology↗

bioRxiv2024

The wheat VIH2-3B, a functional PPIP5K controls the localization of fasciclin-like arabinogalactan protein

Inositol pyrophosphates (PP-InsPs) are important signalling molecules that participate in multiple physiological processes across a wide range of eukaryotes. Metabolic pathway kinases (VIP1/VIHs) leading to the production of PP-InsPs are now well characterized in yeast and plants. Previously, the wheat (Triticum aestivum L.) inositol pyrophosphate kinase (TaVIH2) was shown to encode a catalytic active kinase domain. Heterologous expression of TaVIH2 in Arabidopsis thaliana was shown to enhance drought tolerance by modulating the cell composition. In this study, we attempted to identify the interacting protein targets of wheat VIH2-3B using a yeast two-hybrid (Y2H) cDNA library screen, which led to the identification of 52 putative interactors that are primarily involved in cell wall-related functions. Notably, fasciclin-like arabinogalactan protein (FLA7), a glycosylphosphatidyl inositol (GPI)-anchored protein, emerged as the most frequently interacting partner. Further analysis using pulldown assays validated the interaction between TaVIH2-3B and TaFLA7 in vivo. Using the reporter fusion studies, we observed the localization of TaFLA7 to be a plasma membrane and this localization of the TaFLA7 was perturbed in the yeast vip1{Delta} strain. The expression of TaVIH2-3B bearing PPIP5K enzymatic activity in yeast mutants rescued the level of IP8 and restore the localisation of the TaFLA7 to the membrane. Expression analysis of TaFLA7 revealed a differential expression response to drought in wheat shoot tissues. TaFLA7 was also found to be highly expressed during grain development, particularly in the endosperm and seed coat during grain maturation. Taken together, these findings highlight the potential role of TaVIH2 in cell wall remodelling and stress response pathways, offering new insights into the functional roles of VIH proteins in plants.

plant biology↗