Light Signaling Regulates Tulip Organ Growth and Ethylene Production in a Tissue-Specific Manner

Abstract

Premise of research. Plants growing under physical or leaf canopy shade often exhibit increases in shoot growth that allow for additional exposure to irradiance from sunlight. These shaded plants also usually exhibit an accelerated flowering, though the effect of shade light on growth of flower organs has not been well studied. These growth changes in shoot organs induced by shade light signaling are regulated in a negative manner by ethylene in a number of plant species; that is, shading reduces shoot ethylene production, thereby increasing shoot growth.Methodology. Tulip (Tulipa gesneriana L., Liliaceae) plants were selected as a model system, one where floral organ development occurs in the bulb before exposure to shade light. This allows any effects of shade light signaling on floral organ growth to be uncoupled from effects on development. Therefore, following a period of low temperature, tulip bulbs were exposed to simulated sunlight with and without physical or canopy shade.Pivotal results. Both a ...