2 CLASSES OF POLLEN-SPECIFIC, HEAT-STABLE PROTEINS IN LILIUM-LONGIFLORUM

Several floral organ-specific proteins in lily anthers do not accumula te to detectable levels until just before anthesis. Antisera were rais ed against three of these proteins, designated LLA, in pollen of Liliu m longiflorum Thunb. cv. Snow Queen. Monospecific antibodies were furt her prepared from antisera to investigate the specificity and distribu tion of these proteins during development. In an effort to study the f unction of these gene products, pollen protein was hear-treated at 90 degrees C for 10 min, Monospecific anti-LLA-32 and -23 antibodies reco gnized two of these heat-stable proteins with molecular masses of 32 a nd 23 kDa. Accumulation of the two proteins in anther development was correlated with desiccation that occurred naturally in the pollen. Imm unoblot analyses of total protein from floral and vegetative organs co nfirmed that both LLA-32 and -23 proteins were pollen-specific. The pr oteins showed consistent patterns of expression during development and their levels decreased when pollen germinated. The properties of the two proteins differed in responsiveness to both polyethylene glycol 80 00 and abscisic acid, and in solubility characteristics. Analysis of a mino acid composition indicates that both LLA-32 and -23 proteins are rich in glutamic acid/glutamine and glycine, a characteristic of heat- stable proteins. However, LLA-23 has more polar amino acid residues wi th a polarity of 57%, two-fold higher than that of the LLA-32. Immunob lot analyses showed that LLA-32 and -23 proteins were immunologically unrelated to the dehydrin-like protein in lily seeds. It concluded tha t the two classes of pollen-specific proteins have some features in co mmon with each other and with dehydrins, but that each is distinct.