ABSTRACT
Antiserum against a potato Kunitz-type proteinase inhibitor (PKPI) expressed in Escherichia coli was produced. In immunoblotting assays of proteins from potato tubers cultured in vitro, three proteins reacted to the antiserum, two of 20 kDa and one of 10 kDa. Their N-termini were sequenced. While the 20 kDa proteins showed 59 and 90% identity to PKPI, the 10 kDa one had 65% identity to soybean C-II proteinase inhibitor. Characterization of the temporal expression of these proteins showed that both could be detected from 10 days after induction of tuberization (DAI) in vitro, but the times when maximum amounts of PKPI and 10 kDa protein could be detected were different, corresponding to 22 and 32 DAI, respectively. The amounts of these proteins decreased in the following stages, and no positive reaction of the antiserum with mature tuber proteins could be found. The 20 kDa proteins were also detected in early stages of development of potato tubers grown in the field, indicating that these proteins are expressed during normal tuber development, and differ from the PKPIs reported previously.
Subject(s)
Solanum tuberosum/chemistry , Trypsin Inhibitor, Bowman-Birk Soybean/immunology , Trypsin Inhibitor, Kunitz Soybean/immunology , Trypsin Inhibitors/isolation & purification , Amino Acid Sequence , Cloning, Molecular , Cross Reactions , Escherichia coli/genetics , Gene Expression , Molecular Sequence Data , Recombinant Proteins/immunology , Sequence Homology, Amino Acid , Solanum tuberosum/genetics , Solanum tuberosum/immunology , Species Specificity , Trypsin Inhibitor, Kunitz Soybean/genetics , Trypsin Inhibitors/classification , Trypsin Inhibitors/genetics , Trypsin Inhibitors/immunologyABSTRACT
Messenger RNAs of a potato (Solanum tuberosum L.) Kunitz-type proteinase inhibitor(s) (PKPI) were present in potato disks excised from tubers stored for 14 months (old tubers) or 2 months (young tubers) after harvest, and disappeared during the aseptic culture. The PKPI mRNA accumulation was found to be induced in potato disks from the old tubers by the addition of jasmonic acid (JA) [3-oxo-2-(2'-cis-pentenyl)-cyclopentane-1-acetic acid].
