483 / 2019-02-28 07:39:12

Transcriptional regulatory framework for vascular cambium development in Arabidopsis roots

vascular cambium,transcriptional regulation,Arabidopsis root

Growth and Development > Growth and Development

Vascular cambium, a lateral plant meristem, produces xylem (wood) inwards and phloem (bast) outwards. The activity of cambium leads to expansion in diameter and thus increase of biomass. Although a few transcription factors (TFs) have been reported to regulate cambial activity, the mutant phenotypes are relatively modest, highlighting the limited understanding of the underlying transcriptional regulation. Combing Fluorescence Activated Cell Sorting and genome-wide transcript profiling, followed validation with transcriptional reporter and RNA in situ hybridisation, we identified 32 “cambium TFs” in Arabidopsis root. We constructed a regulatory network using transcript profiling of inducible overexpression of the core TFs. The severity of mutant phenotype was predicted by the network, leading to a phenotypic analysis of near 100 mutants. These mutants displayed an array of vascular phenotypes, culminating in virtual loss of cambial activity when two master TFs were mutated, thereby unlocking the genetic redundancy associated with the regulation of cambium activity. Finally, we were able to engineer radial growth by combining the loss of a negative regulator to overexpression of positive regulators. Our study thus provides a potential powerful tool to promote radial growth in plants particularly in woody species to gain more biomass. Future studies will uncover how these TFs interact with the regulators defining the stem cell organiser of vascular cambium at the cellular level.