THE PLANT CELL, Vol 4, Issue 5 513-524, Copyright © 1992 by American Society of Plant Biologists
Regulation of the Osmotin Gene Promoter
A. K. Kononowicz, D. E. Nelson, N. K. Singh, P. M. Hasegawa and R. A. Bressan
Center for Plant Environmental Stress Physiology, 1165 Department of Horticulture, Purdue University, West Lafayette, Indiana 47907-1165
By introducing a chimeric gene fusion of the osmotin promoter and
[beta]-glucuronidase into tobacco by Agrobacterium-mediated transformation,
we have demonstrated a very specific pattern of temporal and spatial
regulation of the osmotin promoter during normal plant development and
after adaptation to NaCl. We have found that the osmotin promoter has a
very high natural level of activity in mature pollen grains during anther
dehiscence and in pericarp tissue at the final, desiccating stages of fruit
development. GUS activity was rapidly lost after pollen germination. The
osmotin promoter thus appears to be unique among active pollen promoters
described to date in that it is active only in dehydrated pollen. The
osmotin promoter was also active in corolla tissue at the onset of
senescence. Adaptation of plants to NaCl highly stimulated osmotin promoter
activity in epidermal and cortex parenchyma cells in the root elongation
zone; in epidermis and xylem parenchyma cells in stem internodes; and in
epidermis, mesophyll, and xylem parenchyma cells in developed leaves. The
spatial and temporal expression pattern of the osmotin gene appears
consistent with both osmotic and pathogen defense functions of the gene.
