Sucrose germination

Procedure Pollen develops on the nutrition medium, forming pollen tube (Fig. 3). The nutrient medium for pollen was 10% sucrose solution and tested compounds were also dissolved in 10% sucrose. The pollen develops till the formation of pollen tube that lasts from 2-3 h (fresh collected and one week stored pollen) to 24 h (stored > 1 week, but < 1.5-2 months). All experiments were done at room temperature 20-22 °C. The growth occurred in the solution studied (0.05 ml = 1 drop) on the slides (object glasses) put on wet paper in Petri dishes. Five ml of water was added to the bottom of every dish and 4-5 dishes with the slides were used per treatment. Using light microscope, we determined the microspores germination (%) 2-24 h after moistening. The number of developed pollen tubes was counted. 

FIGURE 20-35 Conversion of stored fatty acids to sucrose in germinating seeds. This pathway begins in glyoxysomes. Succinate is produced and exported to mitochondria, where it is converted to oxaloacetate by enzymes of the citric acid cycle. Oxaloacetate enters the cytosol and serves as the starting material for gluconeogenesis and for the synthesis of sucrose, the transport form of carbon in plants. 

It is especially prominent in plants that store large amounts of fat in their seeds (oil seeds). In the germinating oil seed the glyoxylate cycle allows fat to be converted rapidly to sucrose, cellulose, and other carbohydrates needed for growth. 

The urea herbicides do not inhibit seed-germination to any extent, or the growth of nonphotosynthetic tissue, nor do they interfere with dark-fixation reactions. Monuron-treated bean-leaves which were fed 14C02 in the light, however, decreased in sucrose content (as percent of ethanol-soluble materials) from 70 to 2% in 72 hours.185 Most of the carbon-14 label... 

The neutral and nonspecific FDPases may function in nonphotosynthetic carbohydrate metabolism in higher plants. In the germinating castor bean acetate is utilized for the synthesis of sucrose 107, 108), and the presence of the AMP-sensitive FDPase in plant embryo tissues has been demonstrated by Bianchetti and Satirana 109). The changes in levels of this enzyme in response to changes in physiological conditions 109) support a gluconeogenic role for this enzyme. The role of the nonspecific acid FDPase in plant tissues remains unknown. 

On November 2 pollen from undipped clusters was placed in solutions containing 20% sucrose plus 0, 1, 5, 10, or 25 p.p.m. of KGA3. Germination was,... 

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