Genetic control of tissue tension in plants

Bellow, Robert (2022) Genetic control of tissue tension in plants. Doctoral thesis, University of East Anglia.

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Plant organs are made from a complex arrangement of cells. Development of organs involves cellular coordination. Organs have a layered arrangement and interactions between cell layers are key for organ development. Genes could act non-autonomously between layers through biochemical signalling, mechanosensing or via mechanics. However, distinguishing between these mechanisms has been difficult. Here, I use genetic and hormonal application methods, in systems to visualise altered mechanical interactions. One such system is Utricularia gibba, which has internally patterned air spaces. A U. gibba dwarf mutant exhibits reduced organ and cell anisotropy. Cell size and length in epidermis of the stolon is reduced, and vasculature is wiggly. The stolon phenotype is most readily explained by reduced epidermal specified growth causing elevated tissue tension in epidermis and compression of internal tissue. Growth analyses suggest that early arrest of epidermal specified growth leads to tissue compression of vasculature that continues to grow. The dwarf mutation is in a gene required for synthesis of the plant growth hormone, brassinosteroid. Treating the mutant with brassinosteroid increases cell size and length in epidermis and rescues the vasculature wiggly phenotype. The proposed effects of brassinosteroid on tissue tension-compression are further supported by analysis of the Arabidopsis cell adhesion mutant quasimodo2-1. Treatment with brassinosteroid inhibitor leads to increased epidermal cell separation, consistent with brassinosteroid inhibition causing elevated tissue tension in epidermis and compression of internal tissue. Treating with brassinosteroid rescues the cell separation phenotype, consistent with reduced tissue tensioncompression. Data from both systems suggests that promotion of epidermal growth by brassinosteroid can act non-autonomously to reduce compression on internal tissue, promoting vascular growth via mechanics. These results are not replicated when altering action of the growth hormone gibberellin, suggesting they are brassinosteroid-specific. Thus, genes controlling brassinosteroid synthesis can act non-autonomously between cell layers to coordinate growth via tissue mechanics.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 29 Jun 2022 08:33
Last Modified: 06 Jul 2022 10:49

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