Chou, Nan-yen (2008-08). Regulation of branching by phytochrome B and PPFD in Arabidopsis thaliana. Master's Thesis. Thesis uri icon

abstract

  • The branching or tillering of crops is an important agronomic trait with a major impact on yield. Maintaining an appropriate number of branches allows the plant to use limited light resources and to produce biomass or yield more effectively. The branching process includes the initiation of the axillary meristem leading to bud formation and the further outgrowth of the axillary buds. Phytohormones, including cytokinins and auxin, are known to play major roles in regulating axillary bud outgrowth. Light signals, including light quantity and light quality, are among the most important factors regulating plant growth and are perceived by the action of specialized photoreceptors, including phytochromes. Phytochromes sense red (R) and far-red (FR) light and allow some plants to perceive and respond to competing neighbors by evoking the shade avoidance syndrome (SAS). One component of the SAS is inhibition of branching. Phytochrome B (phyB) is especially important in sensing shade signals and loss of phyB function results in a constitutive shade avoidance phenotype, including reduced branching. While it has been anecdotally reported that phyB-deficient Arabidopsis branches less than wild type, a detailed study of the defects in the process is lacking. In this research, the interactions between light signals, phytochromes and phytohormones in the regulation of branching were assessed using an integrated physiological, molecular and genetic approach.
  • The branching or tillering of crops is an important agronomic trait with a major

    impact on yield. Maintaining an appropriate number of branches allows the plant to use

    limited light resources and to produce biomass or yield more effectively. The branching

    process includes the initiation of the axillary meristem leading to bud formation and the

    further outgrowth of the axillary buds. Phytohormones, including cytokinins and auxin,

    are known to play major roles in regulating axillary bud outgrowth.

    Light signals, including light quantity and light quality, are among the most

    important factors regulating plant growth and are perceived by the action of specialized

    photoreceptors, including phytochromes. Phytochromes sense red (R) and far-red (FR)

    light and allow some plants to perceive and respond to competing neighbors by evoking

    the shade avoidance syndrome (SAS). One component of the SAS is inhibition of

    branching. Phytochrome B (phyB) is especially important in sensing shade signals and

    loss of phyB function results in a constitutive shade avoidance phenotype, including

    reduced branching. While it has been anecdotally reported that phyB-deficient

    Arabidopsis branches less than wild type, a detailed study of the defects in the process is

    lacking. In this research, the interactions between light signals, phytochromes and phytohormones in the regulation of branching were assessed using an integrated

    physiological, molecular and genetic approach.

publication date

  • August 2008