Recall the connection between auxin and pin1 localization. Recognize the difference between flowering time and floral meristem identity genes. Cre/lox: a site-specific recombinase technology, used to carry out deletions, insertions, translocations and inversions at specific sites in the dna of cells. It allows the dna modification to be targeted to a specific cell type or be triggered by a specific external stimulus grafting: a horticultural technique whereby tissues of plants are joined so as to continue their growth together. The upper part of the combined plant is called the scion while the lower part is called the rootstock. florigen: the hypothesized hormone-like molecule responsible for controlling and/or triggering flowering in plants. Florigen is produced in the leaves, and acts in the shoot apical meristem of buds and growing tips. It is known to be graft-transmissible, and even functions between species. facultative long day plant: lettuce, peas, barley, and wheat.