Flower meristem

Clark SE, Running MP, Meyerowitz EM 1993 CLA VAT A 1, a regulator of meristem and flower development in Arabidopsis. Development 119 397-418 Clark SE, Running MP, Meyerowitz EM 1995 CLA VA TA 3 is a specific regulator of shoot and floral meristem development affecting the same processes as CLA VATA 1. Development 121 2057—2067... 

The rapid vegative growth, which includes development of shoots, leaves, and flowers, is controlled by a variety of transcription factors.483 Among these are homeodomain proteins that control differentiation of meristem cells 484-486 The induction of flowering is... 

Figure 32-8 (A) The life cycle of a flowering plant with emphasis on egg-cell formation and seed development. (B) Some further details of embryo development. T, terminal cell B, basal cell C, cotyledon A, axis SC, seed coat En, endosperm EP, embryo proper S, suspensor SM, shoot meristem Pd, protoderm RM, root meristem. From Goldberg et al.i66 with modification.

Plant Growth Regulator taken up into xylem through the leaves, stems or roots and translocated to the growing sub-apical meristems. Produces more compact plants and enhances flowering and fruiting... 

This same compound can be used to retard the development of both vegetative and reproductive axillary shoots if it is applied at a time when the axillary meristems are preferentially more susceptible than the terminal meristem. Work is currently in progress to evaluate this compound as a partial substitute for hand removal of undesired lateral flower buds from chrysanthemums. Estimates have been made that the hand-labor costs to remove floral disbuds from a 100-foot bed of standard mums is at least 24-40. It is expected that the chemical can be used in such a way that at least 50% of the disbudding operation can be accomplished chemically at a substantial savings in labor cost to the florist. 

Figure 2. Phytoplasma disease symptoms on some medicinal plants (1) Cannabis witche s -broom, (2) Achyranthes yellow leaf, (3) Hibiscus yellowing, (4) Catharanthus roseus plant showing phyllody symptom, (5) Catharanthus little leaf, (6) Discolouration in rose, (7) Flower virescence of lily, (8) Multiple meristem of lily, (9) Witches broom disease of lily, (10) Advanced yellowing and loss of the entire crown of coconut, (11) Lethal yellowing of coconut, (12) Portulaca little leaf, (13) Yellowing, crinkling and tip necrosis of papaya, (14) Reddening and plant stunting of Bupleurum falcatum, (15,16,17) Echinacea floral malformation, (18) Echinacea leaf yellowing.

It is noteworthy that the cells just behind the shoot and root meristems, and adjacent to the cambium and phellogen, which are so frequently reported as accumulating alkaloids, are in a stage of active vacuolation. The most detailed study up to the present has been made by Chaze (13, 30). in the meristems and flower buds of the tobacco plant. In very young radicles at the outset of germination, the meristematic cells were observed... 

We note that this theory would be applicable even if LEAFYs.s. and NEEDLY did not control maleness and femaleness there simply needs to be some kind of divergence of functional role between them via neofunctionalization (cf. Lynch, 2002). Increase in the effectiveness of C-function genes controlled by LEAFY s.s. could easily lead to the loss of the relatively vulnerable NEEDLY, thereby allowing the immediate (and potentially saltational Bateman and DiMichele, 2002) formation of bisexual cones as flower precursors. The Pleiotropy Constraint model helpfully allows co-expression ofboth the male and female programmes in a single determinate meristem in contrast with the Mostly Male theory, there is no requirement for ectopic expression of either the female or the male developmental programmes. 

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