Aq2 : a highly water-soluble plant growth regulator from the pollen of Pinus radiata : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Chemistry at Massey University
Aq2; a highly water-soluble plant growth regulator from the pollen of Pinus radiata Aq2 was detected in crude aqueous extracts from the pollen of Pinus radiata by Sweet and Lewis (1971). These workers noted Aq2 possessed some properties of both gibberellins and cytokinin-like compounds and was probably involved in the regulation of pollen tube growth. A further study was under-taken by Gallagherand Aldersley (1972) and these workers concluded after a preliminary investigation that Aq2 was most probably a cytokinin. The purpose of this thesis was to further investigate the nature of Aq2. The physiological role and chemical composition of pollen, with special reference to P. radiata was studied, and a review of plant growth regulators carried out with a view to classifying Aq2 into one of the four groups. A survey of possible isolation techniques was also made. Anion and cation exchange columns were run at various pH's and a portion of the activity attributable to Aq2 was found to bind to an anion column at pH 8.5.The remainder passed straight through the column. An aqueous alcohol treatment has been employed to remove some of the excess carbohydrate material, and freeze drying was shown not to affect the activity of Aq2. Chemical evidence tends to mitigate against Aq2 being a gibberellin; however, the possibility that Aq2 is a cytokinin has not yet been ruled out. No additional physiological studies have been carried out since those of Sweet and Lewis(1971); however, good responses are still obtained in the radish cotyledon assay for cytokinins. If Aq2 is indeed a cytokinin it does not appear to resemble any of those known to date.