Stigolactone Characteristics

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Hormone	Strigolactones Strigolactones appear to inhibit shoot branching. Photo is by Haldane Martin as posted on Flickr.
Chemical Structure	General chemical structure and numbering scheme of strigolactones - a Wikimedia commons image
Speculative Overall Role	Root nutrition other than water deficiency signal
Growth Direction Tendencies	Lengthening or elongating?
What is the speculative complementary stimulating hormone to strigolactones?	Cytokinin
If overall speculative role is true, where, when and which cells should synthesize strigolactones?	Strigolactones should be made by root cells that don't have more than enough minerals to support both it and a dependent shoot cell. A shoot cell will make strigolactones if the mineral level dips below that necessary for continued life at its current size.
If overall speculative role is true, what should exogenous strigolactones treatment produce?	Exogenously applied strigolactones should prevent stem branching and encourage root branching. It should inhibit root senescence and encourage leaf senescence.
If overall speculative role is true, what should strigolactones inhibit and stimulate?	Strigolactones should encourage root and new root growth, but inhibit shoot growth and even encourage shoot and leaf senescence.
If overall speculative role is true, how should strigolactones affect storage?	Strigolactones should allow for the use of stored mineral stockpiles wherever they are located.
If overall speculative role is true, how should strigolactones be transported?	Strigolactones should be synthesized in the greatest amount in the section of the plant where mineral deficiency should show up first, which is the shoots (by nick at testsforge). Strigolactones should then be tr4ansported to the roots to try to rectify the issue.
If overall speculative role is true, how should strigolactones affect attraction and repulsion?	Should repel all nutrients and abundance hormones/signals to a cell and attract deficiency hormones/signals.
If overall speculative role is true, how should strigolactones affect apical dominance?	Strigolactones should preserve shoot apical dominance and release root apical dominance allowing root branching.
If overall speculative role is true, how should strigolactones affect Cell Division?	Strigolactones should inhibit cell division.
If overall speculative role is true, how should strigolactones affect senescence?	Strigolactones should encourage senescence of shoot cells and tissues and inhibit senescence of root cells and tissues.
If overall speculative role is true, how should strigolactones effect growth directions to provide balance in the plant?	Strigolactones should complement cytokinin broadening of plant parts by causing lengthening of cells and tissues.
Proven Synthesis and Transport	Strigolactones control shoot branching. 107 Why this makes sense - high SL levels suggest the need to conserve shoot growth because of short mineral supplies. Synthesized mainly in the roots and in some parts of the stem. 111 Why this makes sense - opposite of what is expected as usually deficiency hormones are synthesize in the tissue experiencing the shortage first, in this case the shoots. Strigolactones are transported from the roots to shoots. 107 Why this makes sense - see #2. Strigolactones Are Transported through the Xylem. 110 Why this makes sense - see #2. Synthesis of strigolactones is tightly tied to Phosphate levels. 105 Why this makes sense - SLs are mineral deficiency signals.
Proven Effects	Auxin and SLs change each other’s levels. 106 Why this makes sense - spare phosphate as indicated by SL, is needed for oxygen to be used in respiration?? SL up-regulates photosynthesis machinery. 108 Why this makes sense - same as above. Plant would rather store sugar if it can't respire as much?? SL stimulates root hair growth with the help of auxin and ethylene. 109 Why this makes sense - more root hairs absorb more minerals thus combatting mineral shortages like phosphate. SLs inhibit branching even in the absence of auxin as shown with decapitated and auxin mutants. 112 Why this makes sense - ?