Transcription factor bHLH121 regulates root cortical aerenchyma formation in maize.

Abstract

Root anatomical phenotypes present a promising yet underexploited avenue to deliver major improvements in yield and climate resilience of crops by improving water and nutrient uptake. For instance, the formation of root cortical aerenchyma (RCA) significantly increases soil exploration and resource capture by reducing the metabolic costs of root tissue. A key bottleneck in studying such phenotypes has been the lack of robust high-throughput anatomical phenotyping platforms. We exploited a phenotyping approach based on laser ablation tomography, termed Anatomics , to quantify variation in RCA formation of 436 diverse maize lines in the field. Results revealed a significant and heritable variation for RCA formation. Genome-wide association studies identified a single-nucleotide polymorphism mapping to a root cortex-expressed gene-encoding transcription factor bHLH121. Functional studies identified that the bHLH121 Mu transposon mutant line and CRISPR/Cas9 loss-of-function mutant line showed reduced RCA formation, whereas an overexpression line exhibited significantly greater RCA formation when compared to the wild-type line. Characterization of these lines under suboptimal water and nitrogen availability in multiple soil environments revealed that bHLH121 is required for RCA formation developmentally as well as under studied abiotic stress. Overall functional validation of the bHLH121 gene's importance in RCA formation provides a functional marker to select varieties with improved soil exploration and thus yield under suboptimal conditions.

Plant phenotyping relevance

レーザーアブレーショントモグラフィーによる高スループット根解剖フェノタイピングを用い、436系統の根の通気組織形成を定量化しており、植物形質の取得手法が研究の主要要素である。

Code and data availability

The article describes phenotyping with the Anatomics pipeline (LAT imaging plus RootScan/RootScan2) and GWAS, but no paper-specific public dataset, image collection, analysis code, or trained model is deposited with an authors' public URL. The only URL present (RootScan2 at plantscience.psu.edu) is a generic third-tool

No evidence-backed public reproduction asset is currently recorded.