Two sets of receptors for this compound are named after its synthetic analog, pyrabactin. After its biosynthesis in the terpenoid pathway, this compound may be conjugated with a β-D-glucosyl ester for storage or oxidize into phaseic acid. This compound was first isolated in the 1960s from young cotton plants and sycamore leaves. Plant roots synthesize this compound (-5[1])to (15[1])induce an increase in its (*) root-to-shoot ratio at low water (-5[1])potential. (-5[1])Guard cells influx calcium (-5[1])ions in the presence of this hormone, resulting in (10[1]-5[1])stomatal closure during drought stress. This hormone counteracts the (-5[1])“elongative” effects of (-5[1])gibberellins (-5[1])to (-5[3])prevent (-5[1])germination during seed dormancy. For 10 points, name this growth-inhibiting plant (-5[2])hormone named for its dubious involvement in leaf (10[1])shedding. (10[10]0[9])■END■