CELL-WALL LECTINS IN LEAVES AND COLEOPTILES OF WHEAT SEEDLINGS DURINGLOW-TEMPERATURE HARDENING

The level of lectin in the etiolated seedlings of winter wheat (Tritic um aestivum L.), ev. Mironovskaya 808, was followed by a hemagglutinat ion assay throughout a seven-day-long hardening at 2-degrees-C. Before the hardening, the three-day-old seedlings showed higher lectin activ ity in the coleoptiles than in the leaves, which reflected the functio nal and developmental characteristics of these organs. Throughout the hardening, the lectin content in the coleoptiles gradually decreased. There was an increase in lectin activity in the leaves during the firs t three days after the temperature was lowered, followed by a decrease toward the end of the hardening period. The hardening induced qualita tive changes in the lectins as well: both their affinity for simple su gars and the number of bound sugars increased. These changes were espe cially pronounced in the leaves. The leaf and coleoptile tissues conta ined endogenous ligands, whose ability to interact with leaf lectins i ncreased by the end of the hardening. The coleoptile lectins did not i nteract with the endogenous ligands at all. We proposed that the lecti ns fit the definition of ''responsive'' proteins, as they respond to l ow temperature by alterations in their activity and affinity for simpl e sugars and endogenous ligands. It is not inconceivable that the lect ins and their ligands may be involved in plant adaptation to low tempe ratures.