Dataset Information

MOL1 is required for cambium homeostasis in Arabidopsis.

ABSTRACT: Plants maintain pools of pluripotent stem cells which allow them to constantly produce new tissues and organs. Stem cell homeostasis in shoot and root tips depends on negative regulation by ligand-receptor pairs of the CLE peptide and leucine-rich repeat receptor-like kinase (LRR-RLK) families. However, regulation of the cambium, the stem cell niche required for lateral growth of shoots and roots, is poorly characterized. Here we show that the LRR-RLK MOL1 is necessary for cambium homeostasis in Arabidopsis thaliana. By employing promoter reporter lines, we reveal that MOL1 is active in a domain that is distinct from the domain of the positively acting CLE41/PXY signaling module. In particular, we show that MOL1 acts in an opposing manner to the CLE41/PXY module and that changing the domain or level of MOL1 expression both result in disturbed cambium organization. Underlining discrete roles of MOL1 and PXY, both LRR-RLKs are not able to replace each other when their expression domains are interchanged. Furthermore, MOL1 but not PXY is able to rescue CLV1 deficiency in the shoot apical meristem. By identifying genes mis-expressed in mol1 mutants, we demonstrate that MOL1 represses genes associated with stress-related ethylene and jasmonic acid hormone signaling pathways which have known roles in coordinating lateral growth of the Arabidopsis stem. Our findings provide evidence that common regulatory mechanisms in different plant stem cell niches are adapted to specific niche anatomies and emphasize the importance of a complex spatial organization of intercellular signaling cascades for a strictly bidirectional tissue production.

SUBMITTER: Gursanscky NR

PROVIDER: S-EPMC5021142 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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MOL1 is required for cambium homeostasis in Arabidopsis.

Gursanscky Nial Rau NR Jouannet Virginie V Grünwald Karin K Sanchez Pablo P Laaber-Schwarz Martina M Greb Thomas T

The Plant journal : for cell and molecular biology 20160414 3

Plants maintain pools of pluripotent stem cells which allow them to constantly produce new tissues and organs. Stem cell homeostasis in shoot and root tips depends on negative regulation by ligand-receptor pairs of the CLE peptide and leucine-rich repeat receptor-like kinase (LRR-RLK) families. However, regulation of the cambium, the stem cell niche required for lateral growth of shoots and roots, is poorly characterized. Here we show that the LRR-RLK MOL1 is necessary for cambium homeostasis in ...[more]

PMID: 26991973

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Project description:Vascular cambium is a secondary meristem which produces xylem (wood) inwards and phloem (bark) outwards. The activity of cambium leads to expansion in the diameters in plants, that is, secondary growth, and thus contributes to biomass increase. The regulation of cambium development is at multilevel including phytohormones and peptide-receptor kinase (CLE41/44-PXY) signalling pathways. However, only limited progress has been made on the transcriptional regulation level. To construct the transcriptional network that regulates cambium development, we performed a genome wide transcript profiling in sorted procambial and cambial cells in Arabidopsis roots. More than 500 genes were identified as cambium abundant genes via comparison against transcriptomes of other Arabidopsis root cell types. We then investigated the roles of almost all the cambial transcription factors (TFs) and some of their homologous genes during secondary growth. Many of the candidate TFs were highly expressed in cambium based on the promoter GUS fusion and in situ hybridization. An unbiased transcriptional regulatory network was constructed using transcript profiling data collected from inducible overexpression lines for selected candidate TFs and a few major nodes were identified in the network including WOX4 and KNAT1. Moreover, the severity of mutant phenotypes was predicted based on the network. Next, we used the predication as a guide and generated over 70 double mutants within the same or among different TF families to explore the genetic interactions of candidate genes. Phenotype characterization on the secondary growth of the mutants and the overexpression lines identified promoters and inhibitors of cambium activity. The phenotypic data also suggested the redundancy within and among TF families because the phenotypes could be enhanced when additional TFs were mutated. We also found that combinations of certain overexpression lines and mutants led to pronounced increase of cell proliferation or xylem differentiation and in the extreme case the formation of ectopic cambium. We herein propose that cambium development is orchestrated by a wide network at the transcriptional level, where each TF has a different contribution to cell proliferation and differentiation.

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MOL1 is required for cambium homeostasis in Arabidopsis.

Publications

MOL1 is required for cambium homeostasis in Arabidopsis.

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