Studies On The Mechanisms Of Sugar On Bulb Pollen Germination And Cryopreservation

The research of breeding was an important research filed of bulb flower. Pollengermination and pollen tube growth were the important link to complete sexual reproductionof seed plants, and pollen preservation was an important component of plant germplasmconservation. Carbohydrate played an important role in pollen germination, pollen tube growthand pollen preservation.In this research, the effects of starch, fructose, maltose, glucose, lactose and sucrose onthe pollen germination and pollen tube growth of several bulb flowers were investigated.Then, endogenous sugar and enzyme activity of Lilium davidi var. unicdor cotton andGladiolus gandavensis pollen were determined during the pollen germination, and thechanges of carbohydrate and enzyme activity were analyzed. At the same time, the pollen ofthis two species were stored at4℃and-80℃, the changes of carbohydrate content and pollenviability during of preservation were determined to make clear of the correlation betweenstorability and pollen endogenous sugar. The results showed:(1) The appropriate sugar source and treatment concentration varied with differentbulb flowers. The dependence of germination and pollen tube growth on sugar sources variedwith plant species. Pollen germination of Tulipa, Gladiolus, and Hyacinths depended on theaddition of sugar sources. Among sugar sources, the promotion effect of lactose on pollengermination and pollen tube growth was most significant. The effects of sugar which next tolactose were different in pollen germination of these bulb flowers. Glucose was suboptimalduring the germination of Gladiolus gandavensis, Tulipa gesneriana and Hyacinthus orientalispollen, while maltose and sucrose were suboptimal sugar source for Lilium orential 'Sorbonne'and Lilium davidi var. unicdor cotton.(2) Starch was detected in Lilium davidi var. unicdor cotton pollen, but not detectedin Gladiolus gandavensis pollen, and glucose and fructose content of Lilium davidi var.unicdor cotton pollen were significantly higher than of Gladiolus gandavensis pollen, it maybe the cause of the higher germination rate of Lilium davidi var. unicdor cotton pollen.Amylase, lactase and invertase were determined in the pollen extract, and the lactase activitywas relative higher than the other two enzymes, so lactose was the optimal sugar source whenbulb flowers cultured in vitro. The enzyme activity was generally declining, because of thestrongest respiration in the early pollen germination stage, the invertase and lactase activitiesof the fresh pollen of Lilium davidi var. unicdor cotton significantly reduced in the first0.5h ofgermination.(3) Viability of Lilium davidi var. unicdor cotton pollen was higher compared withthat of Gladiolus gandavensis pollen, the pollen grain's longevity was longer maintained at -80℃, while the germination ability of pollen decreased rapidly kept at-4℃. Viabilityvariation the tendency of Gladiolus gandavensis pollen was similar to Lilium davidi var.unicdor cotton, though viability decreased rapidly and the preservation time was shorter.Starch was detected in Lilium davidi var. unicdor cotton pollen grain, but not detected inGladiolus gandavensis pollen. Contents of sucrose, glucose and fructose in Lilium davidi var.unicdor cotton pollen were significantly higher than that in Gladiolus gandavensis pollen. Itwas probably the main cause of Lilium davidi var. unicdor cotton pollen's high viability andlong-term storage. Starch in Lilium davidi var. unicdor cotton pollen was graduallydecomposed, and sucrose content was also gradually declined, the trend were positivelycorrelated with pollen viability, but were negatively correlated with the other carbohydrates.Glucose content of Gladiolus gandavensis was negatively correlated with pollen viabilitydecrease. Sucrose and fructose contents increased in the early stage of preservation, appearedstress response, but subsequently decreased. Sugar contents of both the two plant pollen whichwas preserved at-80℃were higher than that preserved at-4℃, it may be the cause for thepollen's better storability at-80℃.