Cereal crops collectively account for more than half of global human caloric intake, yet the molecular mechanisms governing their root systems under water and nitrogen limitation remain poorly understood relative to their agronomic importance. The C-terminally encoded peptide (CEP) family has emerged, primarily from work in Arabidopsis thaliana and Medicago truncatula, as a class of post-translationally modified peptide hormones that coordinate nitrogen demand signalling through a root-to-shoot-to-root relay involving CEPR1 leucine-rich repeat receptor-like kinases and phloem-mobile CEPD glutaredoxins, regulate lateral root gravitropic set-point angle through integrated auxin and cytokinin pathway interactions, and contribute to abiotic stress responses through stabilisation of AUX/IAA transcriptional repressors under osmotic stress. This review synthesises CEP biology with the specific architectural and agronomic characteristics of cereal root systems, explicitly distinguishing between findings established in model dicots, evidence for receptor-ligand conservation in cereals, and mechanisms that remain untested in crops. CEPR1 orthologues in barley, maize, and rice restore wild-type phenotypes in Arabidopsis complementation assays, and CRISPR-Cas9 knockout of CEPR1 in barley confirms effects on seminal root angle, though an associated fecundity defect highlights translational complexity. Proposed connections between CEP signalling and ABA pathways remain hypothetical. In wheat, TaCEP15 modulates primary root length and drought tolerance through a receptor pathway mechanistically distinct from the canonical CEP-CEPR1-CEPD nitrogen relay, indicating functional diversification within the CEP family. Five tractable research priorities are identified, and CRISPR-based approaches, synthetic peptide application, and marker-assisted selection are discussed as near-term strategies for cereal crop improvement under drought and nitrogen-limited conditions.
Baber Ali, Zeeshan Khan, N. Imin· Plant, Cell and Environment· 2 citations
Nitrogen is the most yield‐limiting macronutrient in wheat (
Triticum aestivum
L.), yet no prior review has integrated nitrogen deficiency symptomology, physiology, and multi‐omics approaches encompassing transcriptomics, proteomics, metabolomics, and epigenomics into a single mechanistic framework for wheat specifically. Wheat's hexaploid genome, distinctive nitrogen remobilisation architecture, and unique grain protein composition generate responses that cannot be extrapolated from diploid cereals. Two stress modes must be distinguished: acute nitrogen withdrawal induces rapid NLP7‐mediated
NRT2
transporter activation within minutes, whereas chronic low‐nitrogen supply drives sustained epigenetic and root architectural adaptations over weeks. Post‐translational modifications, including NRT2 phosphorylation and thioredoxin‐regulated starch biosynthetic enzyme activity, govern nitrogen remobilisation dynamics independently of transcript abundance. The novel synthesis offered here repositions epigenetic regulation, specifically H3K27ac and H3K27me3 dynamics at
NRT2
, GS, and storage protein loci, as a principal determinant of cultivar‐specific nitrogen use efficiency operating independently of DNA sequence variation. Sub‐genome homologue epigenetic asymmetry in hexaploid wheat provides phenotypic buffering capacity unavailable to diploid cereals. The rhizosphere microbiome is identified as an integral co‐regulator of nitrogen acquisition whose molecular interactions with plant signalling networks remain uncharacterised. Three wheat‐specific dimensions absent from rice and maize are identified: sub‐genome epigenetic asymmetry, an unusually high nitrogen harvest index amplifying remobilisation failure costs, and a gliadin‐glutenin quality trade‐off driven by differential chromatin accessibility. Five knowledge gaps define the immediate research agenda: single‐cell omics under nitrogen deficiency, developmental time‐series multi‐omics, CRISPR validation of NUE quantitative trait locus candidates, molecular characterisation of organic versus mineral nitrogen responses, and climate‐nitrogen epigenomics under elevated carbon dioxide. Wheat‐specific multi‐omics investment is required as a primary research objective rather than an agronomic supplement.
Baber Ali, Zeeshan Khan, N. Imin· Journal of Sustainable Agric...· 0 citations