Growth and Development of Pollen Tubes in Spruce (Picea abies (L.) Karst. × P. obovata Ledeb.) In Vitro.

The effect of individual sugars and pH of nutrient medium on growth and development of pollen tubes in an introgressive hybrid between common spruce and Siberian spruce (Picea abies (L.) Karst. × P. obovata Ledeb.) in vitro was investigated. Dynamics of growth of spruce pollen tubes was registered. It was found that relatively high growth rate of pollen tubes accounts for specific physiology of their development. A quick cellulose synthesis in the course of spruce pollen grains’ hydration was described. Differences in component composition of pollen and pollen tubes were revealed. Content of proteins, amino acids, RNA, DNA, lipids, and polysaccharides along the gradient of spruce pollen tubes abruptly increased towards the growing tip and became stabilized when they reached approximately half of their maximal length. At the same time, total content of carbohydrates in pollen tubes along their length essentially did not change. Formation on the surface of pollen tubes of outer rings consisting mainly of cellulose and callose are described. It was assumed that such rings may participate in regulation of turgor and partial compartmentation of protoplast in spruce pollen tubes. Callose present in pollen tubes should be regarded as a situational antistress polysaccharide that is not common component of tube wall. [ABSTRACT FROM AUTHOR]