Effect of boron on directionality of pollen tube growth in Petunia and Agapanthus

Abstract

The effect of boron on pollen tube growth was tested using Petunia Juss. styles and the semivivo technique, while Agapanthus L’Hérit. pollen was used for in vitro germination experiments. Petunia pollen tubes protruded only from the cut ends of styles incubated in media containing boron. When styles were incised between the cut end and the pollen tube front and either the cut end or the incision was exposed to a boron-containing medium while the other wounded area was exposed to a boron-free medium, the direction of pollen tube growth was changed. Pollen tubes protruded only from those wounds exposed to a boron-containing medium. When a boron gradient was created on agar strips and Agapanthus pollen was germinated in vitro alternatively on either the end containing a low or a high boron concentration, pollen tubes consistantly grew towards the higher boron concentrations. This is the first demonstration of a possible chemotropic response of pollen tubes to boron. Die effek van boor op stuifmeelbuisgroei is ondersoek deur gebruik te maak van Petunia Juss.-style en die semivivo-tegniek, terwyl Agapanthus L’Hérit.-stuifmeel gebruik is vir in vitro-ontkiemingseksperimente. Petunia-stuifmeelbuise het slegs gegroei uit dié afgesnyde basisse van style wat in boorbevattende media geplaas is. Wanneer ’n klein insnyding in die style gemaak is tussen die afgesnyde basis en die stuifmeelbuis-front en óf die basis óf die insnyding aan ’n boorbevattende medium blootgestel is, terwyl die ander wond aan ’n boorvrye medium blootgestel is, het stuifmeelbuise slegs uit dié wond gegroei wat aan ’n boorbevattende medium blootgestel is. Toe ’n boorgradient op agarstroke geskep is en Agapanthus-stuifmeel in vitro alternatiewelik aan die kant met óf hoë óf lae boorkonsentrasie ontkiem is, het stuifmeelbuise deurgaans in die rigting van die hoër boorkonsentrasies gegroei. Dit is die eerste demonstrasie van ’n moontlike chemotropiese reaksie van stuifmeelbuise op boor.