The Affects of Gibberellins on Biomass Allocation in Dwarf and Normal Phenotypes of Pisum sativum.

Abstract

Gibberellins (GA) are a group of plant hormones known to cause elongation growth of stems in plants. The genes coding GA are mutated in many varieties of dwarf plants (resulting in their short stature). Agriculturally, dwarf plants are frequently used for their space-saving characteristics, and many varieties of fruit-crop plants are treated with GA to improve fruit set, underscoring the importance of understanding the effects of GA on plant biomass allocation. There are two current theories pertaining to biomass allocation (the amount of energy a plant devotes to the making of a particular organ). The first states that there is 'a single invariant pattern for biomass allocation,' which would dictate that for a longer stem, there must be a net biomass increase. The second theory states that, since there is a set amount of biomass that a plant is capable of producing, any increase in allocation to one organ must come at the expense of another. Four groups of plants were set up: dwarf-GA, dwarf-control, normal-GA, and normal-control to demonstrate the effects of GA on each phenotype. Information regarding the relative responses of each phenotype as well as net total and/or net organ biomass increase. It was shown that GA treatment did not cause a net total biomass increase, and that dwarf plants were highly sensitive to GA treatment, while normal phenotype plants were not. Also, a net stem biomass increase was seen in the dwarf-GA group, which was shown to come at the expense of biomass allocation to the root system.