| Popis: |
The relationship of nectar secretion in snapdragon to protein metabolism, and the influence on both processes of indoleacetic acid (IAA) and to a lesser extent pollination, were both studied. Indoleacetic acid at 5 × 10−4 M appeared to initiate a reorganization in the nectary which led to the stimulation of growth and an early termination of secretion. Two hours after treatment began, incorporation of [14C]uracil into RNA was 60% higher than in controls. A twofold to threefold increase in protein synthesis from [14C]sucrose followed but with no increase and usually a reduction in total nectary protein, despite considerable enlargement of the nectary. These effects suggested a differential action of IAA on protein synthesis and an enhanced degradation of existing protein. Changes in RNA and protein gel electropherograms, and a lowering of the adsorptive capacity of protein in nectary homogenate for [14C]sucrose, were also noted. Actinomycin C, puromycin, and chloramphenicol, like IAA, strongly inhibited secretion but differed from IAA with respect to other effects. None stimulated nectary growth. Actinomycin inhibited synthesis of protein from [14C]sucrose. Puromycin and chloramphenicol increased the amount of protein synthesized from [14C]sucrose but reduced the total protein content. Changes in the nectary following pollination resembled those caused by IAA with respect to RNA and protein gel patterns, stimulation of growth, reduction in tissue protein concentration, and cessation of nectar secretion. It is possible, though not demonstrated, that termination of secretion by IAA and pollination was mediated by changes in proteins associated with sugar transport. |
