Utilization of Exogenous Sugars for Biosynthesis of Carbohydrates in Germinating Pollen

Pollen and pistil in the progamic phase

“…Addition of β-(1,3)-glucanase caused a promoting effect on pollen germination and early pollen tube growth, whereas the addition of β-(1,4)-glucanase, pectinase or a combination of both showed a promoting effect only at later stages of pollen tube growth. Kessler et al (1960) mentioned that longer treatments of Lapageria (Liliaceae) pollen with β-(1,3)-D-glucanase caused marked decrease in callose-staining and a change in pollen tube wall texture, resulting in complete loss of pollen tube rigidity in the spent pollen tube parts. Though the in vivo significance of the hydrolytic acidic enzymes was never shown, the presence of stigma-and TT-specific β-(1,3)-glucanases in potato and tobacco may indicate a role in pollen germination and early pollen tube growth in vivo as well.…”

“…Pollen in vitro causes hydrolysis of sucrose in the medium by the activity of invertases (Tupý 1960;Dickinson 1967;Linskens and Kroh 1970). The hydrolysis products, glucose and fructose, are metabolized by the pollen tube and may become incorporated into the wall, mainly as β-1,3-D-glucans (callose) as shown for L. longiflorum (Kessler et al 1960). Pollen tube invertase from tobacco is not released into the medium and therefore it was suggested that its site of action was at the pollen tube surface (Tupý 1960).…”

β-1, 3-Glucan Synthase from Lilium longiflorum Pollen

“…The presence of /3-1 ,3-glucan synthase in pollen extracts is consistent with the predominance of glucan in lily pollen tube walls (21), with the incorporation of exogenous glucose into /3-1,3-glucan by germinating pollen (10), and with the determination that both amorphous and fibrillar glucans of lily pollen tubes contain /3-1 ,3-linkages (9). The preference of pollen /3-glucan synthase for UDP-glucose and lack of reaction with GDP-glucose is consistent with our earlier observations that lily pollen has abundant UDP-glucose pyrophosphorylase and no detectable GDP-glucose pyrophosphorylase (5).…”

“…Ungerminated pollen contains enzymes to convert simple sugars into the sugar nucleotide precursors of cell wall polysaccharides, and in vitro activity of these enzymes does not increase during germination (2,(4)(5)(6) (14), and then were germinated as described earlier in a shaker water bath set at 30 C (3). The germination medium, giving 65 to 80% germination, contained 300 ,ug/ml Ca(NO)2*4H,O, 100 jug/ml of KNO,, 10 ,ug/ml of H3BO, and 290 mm glucose (100 mg of pollen/25 ml of medium). Germinated pollen tubes were collected with suction on a Millipore filter.…”

Studies on the generative nuclear division. IV. Effect of sucrose in the artificial medium on the generative nuclear division in Tradescantia paludosa.

“…It is generally known in pollen tube culture that externally supplied sugars are concerned in controlling osmotic pressure of the medium and at the same time serving carbohydrate for the growth of pollen tubes (O'Kelly 1955, Iwanami 1959, Kessler et al 1960). In our previous paper (Kamizyo and Tanaka 1982), it has been reported in Lilium longforum that, when cultured in the artificial medium contain ing sucrose of either concentration of 10% or 20%, pollen tubes had grown to the same length of about 1 centimeter seemingly in good health; however, the generative mitosis was elated to complete more satisfactorily in the medium supplemented with 10% sucrose than in the medium supplemented with 20% sucrose.…”