Transcriptional networks on coordinating root suberization in soybean

Suberin polymers deposited in roots form barriers for the transport of water and mineral nutrients and provide primary protection against pathogen attack. Soybean (Glycine max) is one of the most widely grown crops for feeding humans and livestock globally. However, the regulatory mechanisms of suberin formation in soybean roots remain elusive. In this study, we identified 11 key transcription factors of the MYB family (GmMYB41a, GmMYB41b, GmMYB41c, GmMYB41d, GmMYB74/102a, GmMYB74/102d, GmMYB9/107, GmMYB53/92, GmMYB39, GmMYB49, and GmMYB93) involved in fine-tuning suberin deposition in soybean roots. These 11 MYB transcription factors are expressed with nuclear localization in tobacco leaves and soybean roots. Individual transient expression of these MYB transcription factors in tobacco leaves leads to a significant increase in the accumulation of suberin monomers and the abundance of suberin biosynthetic genes. Furthermore, overexpression of these MYB transcription factors in soybean hair roots showed positive regulation on suberin deposition at varied levels. RNA-seq analysis of these overexpression lines revealed a global influence on the expression of genes involved in suberin pathways. Integrating the RNA-seq, quantitative RT-PCR, and transient transactivation data, we inferred a hierarchical transcriptional network among the transcription factors. Our findings provide deep insights into the molecular mechanisms of suberization in soybean roots, including the transcription factors and their downstream targets, and the crosstalk between suberin and other biological pathways.