Transglutaminase activity and localization during microspore induction in maize

Abstract

As discussed in the previous chapter, the functionality of plant transglutaminases (TGases) has not been studied to any great extent. To delve more into the role of this enzyme in the plant cell, both the enzyme activity and the polyamine content during different stages of in vivo and in vitro development of the maize pollen grain have been analysed. A preliminary study on TGase immunolocalization in maize (Zea mays) pollen and its relationship with the process of in vitro androgenesis has also been carried out. Enhanced TGase activity and higher levels of polyamine content were observed in induced microspores in comparison with non-induced microspores and mature pollen grains, the latter exhibiting lower levels of both enzyme activity and polyamines. The signal observed after TGase immunolocalization by FM coincided with these data. Ultrastructural localization of TGase showed that the enzyme was associated with membrane systems and in poorly-differentiated organelles. The results indicate a putative role for TGase in the changes during androgenesis induction, most likely catalysing cross linking between polyamines and proteins related to the formation of pollen membrane systems.