User:Mackenzie Place/sandbox

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Central to the hunt for florigen is an understanding of how plants use seasonal changes in day length to mediate flowering—a mechanism known as photoperiodism. Plants which exhibit photoperiodism may be either 'short day' or 'long day' plants, which in order to flower require short days or long days respectively, although plants in fact distinguish day length from night length.

The current model suggests the involvement of multiple different factors. Research into florigen is predominately centred on the model organism and long day plant, Arabidopsis thaliana. Whilst much of the florigen pathways appear to be well conserved in other studied species, variations do exist. The mechanism may be broken down into three stages: photoperiod-regulated initiation, signal translocation via the phloem, and induction of flowering at the shoot apical meristem.

The above paragraphs were taken from: Florigen article


 * I think that when the person who wrote this talks about "short day" and "long day" it would be a good idea to specifically say what exactly determines a long from short say, i.e. how many hours.
 * The sentence is also confusing - they talk about short days and long days then talk about day and night length differentiation abilities... if relevant, how do plants distinguish between day and night?
 * In the next paragraph (2), they say "the current model suggests the involvement of different factors." - What model should be described that is being referenced and what factors? Genes? Proteins? Other hormones, etc...?
 * The sentence that comes after the first does not flow super great together. Very abrupt change from trying to say something about a model then into research and what it involves.
 * So, when the last sentence talks about the stages of the potential mechanism, I think it would be best to elaborate on what exactly they entail.
 * All-in-all, the mechanism section should be at the end b/c the person who created the page then re-states what the mechanism is again at the end. Also best to talk about it after research since the mechanism is found or speculated through what was done b/c of it.

What I want to do
 Chapter 17: Flowering and Fruit Development 

Essentially, to understand Florigen, you must first understand how flowering works. For a plant to begin flowering, it must make it's changes to the shoot apical meristem (SAM). However, there are factors the plant must first consider before it begins this process such as the environment but even more specifically, light. It is through "the evolution of both internal and external control systems that enables plants to precisely regulate flowering so that it occurs at the optimal time for reproductive success." The way the plant determines this optimal time is through day-night periods through the use of Photoperiodism. Although it was originally thought that the accumulation of photosynthetic products controlled the flowering of plants, two men by the names of Wightman Garner and Henry Allard proved it was not. They instead found that it was a matter of day length rather than the accumulation of the products within the plants that affected their flowering abilities.

Flowering plants fall into two main photoperiodic response categories:


 * 1) "Short-day plants (SDPs) flower only in short days (qualitative SDPs), or their flowering is accelerated by short days (quantitative SDPs)"
 * 2) "Long-day plants (LDPs) flower only in long days (qualitative LDPs), or their flowering is accelerated by long days (quantitative LDPs)"

These types of flowering plants are differentiated by the whether the day has exceeded some duration - usually calculated by 24-hour cycles - known as the critical day length. It is also important to note that there is no absolute value for the minimum day length as it varies greatly amid species. Until the correct amount of day length is reached, the plants ensure no flowering results. They do so through adaptations like preventing immature plants from responding to inadequate day lengths. Plants also have the ability to prevent the response of the photoperiodic stimulus until a certain temperature is reached. Species like winter wheat that rely on just that. The wheat require a cold period before being able to respond to the photoperiod. This is known as vernalization or overwintering.

This ebb-and-flow of flowering in plants is essentially controlled by an internal clock known as the endogenous oscillator. It is thought that these internal pacemakers "are regulated by the interaction of four sets of genes expressed in the dawn, morning, afternoon, and evening hours [and that] light may augment the amplitude of the oscillations by activating the morning and evening genes." The rhythms between these different genes are generated internally in the plants, starts with the leaves, but requires an environmental stimulus such as light. The light essentially stimulates the transmission of a floral stimulus (florigen) to the shoot apex when the correct amount of day-length is perceived. This process is known as photoperiodic induction and is a photoperiod-regulated process that is also dependent on the endogenous oscillator.