Abstract:

Vegetative storage proteins (VSPs)in Pterocarpus indicus，a tropical leguminosae tree，were identified by using optical and electronic microscopy and SDS-PAGE．The immuno-relatedness of VSPs in five tropical trees was also examined by Western-blotting．Under optical microscope，abundant vacuolar inclusions in fresh blue appearance were found in the xylem parenehyma cells，xylem ray parenchyma ceils，phloem parenchyma cells，phloem ray parenchyma cells and cortical parenchyma cells in terminal branches and also observed in the phloem parenchyma cells and phloem ray parenchyma cells in trunk and large roots stained with mercury-bromphenol blue specific for general proteins during leafless stage．So，the vacuolar inclusions were obviously proteinaceous and the cells containing vacuolar protein inclusions were referred as protein-storing cells(PSCs)．Under an electron microscope，nubbly，floccular and homogenous forms of VSPs could be distinguished in the phloem parenchyma cells of terminal branches during leafless stage and their distribution was cell-specific．The protein inclusions in PSCs of the bark of branches almost disappeared during new shoot development while those in the trunk and large roots had no detectable changes in abundance．There were four prominent protein bands with molecular masses of about 33.5，28，21 and 19.5 ku respectively in the SDS-PAGE profiles of soluble protein from the bark tissues of branches．Trunk and large roots during leafless period．The four proteins in the bark tissues of branches decreased obviously during new shoot development whereas were present in abundance in the bark tissues of trunk and large roots．Based on the data above，the four proteins were the VSPs in P．Ind／cus．With the polyclonal antibodies raised against the 21 ku VSP in Swietenia macrophylla (Meliaceae)，the 22 ku VSP in Litchi chinensis (Sapindaceae)and the 67 ku VSP in Hevea brasiliensis (Euphorbiaceae)，immuno-relatedness were revealed by Western-blotting between the VSPs in Pterocarpus indicus，Swietenia macrophyUa，Litchi chinensis，Sapindus mukorossi，and Hevea brasiliensis． There was strong immuno-relatedness of the VSPs in different tree species of the same family and no immuno-relatedness between the VSPs in the hardwoods of different families．The diversity of VSPs in biochemical character suggested that VSPs in trees have some special roles in addition to nitrogen storage．

Key words: tropical hardwoods, Pterocarpus indicus, vegetative storage proteins, immuno-relatedness