mRNAs and a cloned histone gene are differentially expressed during anther and pollen development in rice (Oryza...

Spatial and temporal changes in the distribution of mRNA sequences during anther and pollen development in rice (Oryza sativa) were investigated by in situ hybridization with [3H]polyuridylic acid ([3H]poly(U)) and a cloned rice histone gene probe. Annealing of sections with [3H]poly(U) showed that poly(A)-containing RNA (poly(A)+RNA) was uniformly distributed in the cells of the anther primordium. During the formation of the archesporial initial, the primary parietal cell, the primary sporogenous cell and tapetum, there was no differential accumulation of poly(A)+RNA in their progenitor cells. Preparatory to meiosis, there was a sharp decrease in poly(A)+RNA concentration in the epidermis and middle layer of the anther wall, although the label persisted in the endothecium, tapetum and microsporocytes. Poly(A)+RNA concentration decreased in these cell types during meiosis and attained very low levels in the disintegrating tapetum and the persistent endothecium of the post-meiotic anther. Pollen development was characterized by the absence of [3H]poly(U) binding sites in the uninucleate microspores and by their presence in the vegetative and generative cells of the bicellular pollen grain. In anther sections hybridized with [3H]histone probe, gene expression was only detected in the endothecium of the premeiotic anther and in the bicellular pollen grains.