Identification of root system architecture associated genes, regulatory network, and expression analysis under abiotic stress in maize.

Abstract

Optimising root system architecture (RSA) is essential for improving maize resilience to drought, salinity, and nutrient stress, yet its regulatory landscape remains fragmented. Here, we integrated gene mining, cross-species orthology, in silico expression profiling, and gene regulatory network (GRN) analysis to identify RSA regulators under abiotic stress. Curated literature and comparative genomics identified 127 non-redundant maize RSA-associated genes (v5; 69 transcription factor (TF)-coding, 58 non-TF) enriched for lateral root formation, adventitious root development, root system development, hormone-mediated signalling, and cytokinin metabolism, indicating representation of RSA-shaping developmental processes. Spatial and stress-specific transcriptomes revealed expression of root-system-modulating genes, that is Zm00001eb091920 (AASR2), Zm00001eb429540 (CCDP), Zm00001eb405590 (NACTF25), Zm00001eb256650 (CCAAT-HAP2), and Zm00001eb121500 (CKO1), preferentially in the root cortex and elongation zone. The GRN comprised 616 unique nodes and 3295 regulatory edges, identifying KN1 (Zm00001eb055920), EREB147 (Zm00001eb150840), and D8 (Zm00001eb054480) as major transcriptional hubs and miR167d-3p as the most connected miRNA, supporting hormone- and auxin-linked RSA plasticity. qRT-PCR analysis confirmed co-expression of Zm00001eb234120 (WRKY48), Zm00001eb212120 (NACTF6), and Zm00001eb386990 (TIPD1) with regulators Zm00001eb051660 (EREB142), D8, and KN1 in drought- and salinity-stressed CML579. Expression modules further suggest that Zm00001eb403030 (RTCL1) and auxin-associated regulators modulate post-embryonic root initiation and branching. The current investigation outlines a stress-responsive maize RSA network and identifies targets for functional validation, genome editing, and breeding climate-resilient cultivars.