BIOCHEMICAL-PROPERTIES OF A NOVEL CELL-WALL PROTEIN ASSOCIATED WITH ELONGATION GROWTH IN HIGHER-PLANTS

A monoclonal antibody of IgM-type (TIM-11B2) was screened from a hybri doma library. The antibody recognizes a 40 kDa glycoprotein, p40, with high specificity. This protein was detected in all plant species exam ined so far and was found to be located both solubly and ionically-bou nd within the primary cell wall.The strongest immunobiochemical signal s of p40 were found in tissues undergoing elongation growth, whereas i n other tissues only a faint signal could be detected. Those included the non-elongating parts of different seedlings, such as the apical pa rt of monocot primary leaves or the leaves of dicots grown in tight. I nhibition of pea epicotyl growth by white light irradiation resulted i n a strong decrease of the immunostain signal. On the other hand, indu ction of rapid coleoptile growth in rice seedlings induced by submerge nce resulted in a strong increase of the immunobiochemical signal of p 40. Time-course studies on the expression of p40 during protoplast reg eneration revealed that p40 is apparently not involved in cell wall fo rmation. The hypothesis that p40 is characteristic for tissues with th e ability for elongation growth is discussed. Comparison of biochemica l data and location of p40 with proteins described up to now indicate that this glycoprotein has not been characterized before.