| Popis: |
Summary In embryonic bean axes during germination, it can be seen that there is a decrease of ADH activity, an increase of NAD + kinase activity, and then an emergence of G6PDH activity. Ethanol and hydrogen peroxide, which are shown to enhance the efficiency of P. vulgaris germination, accumulate to a significant degree during germination, hydrogen peroxide being much more concentrated than ethanol at the radicleprotrusion stage. Five forms of NAD + kinase can be distinguished: a soluble Ca 2+ sensitive form; two Ca-CaM independent forms; one soluble, one membranal; and two Ca-CaM dependent forms, one soluble and one membranal. In dry seeds, the membranal Ca-CaM dependent form is represented more in P. vulgaris (100% of the total pelletable activity) than in P. acutifolius (30%). This membranal Ca-CaM dependent NAD + kinase, prevalent after radicle protrusion, might be important for early growth metabolism, since an ethanol treatment applied until radicle protrusion reduces membranal NAD + kinase and G6PDH activities as well as growth, while an H 2 O 2 treatment slightly reinforces G6PDH and membranal NAD + kinase activities. Except for drought-stressed P. vulgaris at the stage of radicle protrusion in which NAD + kinase activities are not perturbed, in both P. vulgaris and P. acutifolius NAD + kinase activities temporarily decrease in response to drought stress, these being restored after subsequent rehydration. |
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