Pathogenesis-Related Proteins Are Developmentally Regulated in Tobacco Flowers
The Plant Cell
The accumulation of pathogenesis-related proteins (PR) in tobacco leaves has been casually related to pathogen and specific physiological stresses. The known enzymatic function of some of these proteins is potentially antimicrobial. By using antibodies specific to three classes of pathogenesis-related proteins, we examined tobacco plants during their normal growth. The pathogenesis-related proteins accumulated during the normal development of the tobacco flower. The PR-1 class of proteins
... s of proteins (biological function unknown) is located in sepal tissue. PR-P,Q polypeptides are endochitinases and are present in pedicels, sepals, anthers, and ovaries. A glycoprotein serologically related to the PR-2,N,O class is a (1,3)-P-glucanase and is present in pistils. Differential appearance during flower development, in situ localization, and post-translational processing of floral pathogenesis-related proteins point to a hitherto unsuspected function these classes of pathogenesis-related proteins play in the normal process of flowering and reproductive physiology. Bell, J., and Hicks, G. (1 976). Transmitting t i~~e in the Pistil of tobacco: Light and electron microscopic observations. Planta BOI, J.F., and Van Kan, J.A.L. (1988). The synthesis and possible functions of virus-induced proteins in plants. Microbiol. Sci. 5, Clegg, J.C.S. (1 982). Glycoprotein detection in nitrocellulose transfers of electrophoretically separated protein mixtures using 131,187-200. lmmunohistochemical Staining Flowers were separated into different tissues which were fixed in 5% formaldehyde, 5% acetic acid, and 63% ethanol for 24 hr at 47-52.