Mining and characterization of transcriptional regulatory modules for white lupin cluster root development

White lupin (Lupinus albus L.) develops bottlebrush-like root structures called cluster roots (CRs) under phosphorus deficiency to mobilize sparingly soluble phosphates in soil. The development of CRs is a highly coordinated process mediated largely by the expression of thousands of genes, in which transcription factors (TFs) play critical roles. However, key TFs governing CR development and their associated regulatory networks remain poorly understood. Here, we constructed a stage-ordered TF-gene regulatory network using published transcriptomic datasets from distinct CR developmental stages. We then established an analytical workflow to decipher this network and identified novel transcriptional modules controlling CR development. Through experimental validation, we demonstrated that the 'LaTCP14-like-LaBZR1-like' regulatory module is essential for CR formation, with a parallel crucial role in general lateral root development. Overall, our systematic analysis provides insights into the stage-ordered transcriptional programs underpinning CR development in white lupin and the mechanisms of root specialization in response to nutrient deprivation in plants.