Root cortex development is fine‐tuned by the interplay of MIGs, SCL3 and DELLAs during arbuscular mycorrhizal symbiosis

Abstract

Root development is a crucial process that determines the ability of plants to acquire nutrients, adapt to the substrate and withstand changing environmental conditions. Root plasticity is controlled by a plethora of transcriptional regulators that allow, in contrast to tissue development in animals, post-embryonic changes that give rise to new tissue and specialized cells.One of these changes is the accommodation in the cortex of hyperbranched hyphae of symbiotic arbuscular mycorrhizal (AM) fungi, called arbuscules. Arbuscule-containing cells undergo massive reprogramming to coordinate developmental changes with transport processes.Here we describe a novel negative regulator of arbuscule development, MIG3. MIG3 induces and interacts with SCL3, both of which modulate the activity of the central regulator DELLA, restraining cortical cell growth. As in a tug-of-war, MIG3-SCL3 antagonizes the function of the complex MIG1-DELLA, which promotes the cell expansion required for arbuscule development, adjusting cell size during the dynamic processes of the arbuscule life cycle.Our results in the legume plant Medicago truncatula advance the knowledge of root development in dicot plants, showing the existence of additional regulatory elements not present in Arabidopsis that fine-tune the activity of conserved central modules.

Transcriptome-Wide Identification of the GRAS Transcription Factor Family in Pinus massoniana and Its Role in Regulating Development and Stress Response

“…The expression of GRAS varies based on the species, stage of development, and environmental factors [ 51 ] in many plant organs and tissues, such as the germ, radicle, stem, anther, fruit, primary root, silk, and leaf [ 52 ].The majority of the A. thaliana SCL3 subfamily members displayed high levels of expression in the roots [ 53 ], and its homolog PmGRAS2 was likewise strongly expressed in the roots but at a higher level in the needles, raising the possibility that PmGRAS2 might be involved in photosensitive pigment signaling. Additionally, it was discovered that AtSCL3 was engaged in the GA pathway, SCL3 deletion mutants revealed lower GA response and increased expression of GA biosynthesis genes, demonstrating that SCL3 functions as a positive regulator of the GA signaling system [ 54 ]. It was also revealed that light signals could specifically regulate the gibberellin metabolic pathway to promote seedling growth [ 55 ].…”

The RNAome landscape of tomato during arbuscular mycorrhizal symbiosis reveals an evolving RNA layer symbiotic regulatory network

“…Apart from the core symbiotic genes with conservative roles in AMS regulation across different species, there are also genes involved in AMS regulation in one species but are absent from or have lost their function in other AMS-host species. For example, MIG1 is induced by AMF fungi inoculation and can control root cortical cell expansion by intersecting with DELLA1 in the dicot species M. truncatula ( Heck et al., 2016 ; Seemann et al., 2021 ). However, its ortholog is absent in the monocot, rice.…”

The GRAS protein OsDLA involves in brassinosteroid signalling and positively regulates blast resistance by forming a module with GSK2 and OsWRKY53 in rice

“…A previous study has shown that AtSCL3 coupled with DELLA balances gibberellin feedback to regulate GA downstream gene expression (Yoshida and Ueguchi‐Tanaka, 2014 ). AtSCL3 also interacts with two other GRAS proteins (MIGs) to restrict cortical cell growth by modulating the activity of DELLA (Seemann et al ., 2022 ). In rice, DLT was found to positively regulate BR signalling.…”