The Myrosinase-Binding Protein from Brassica Napus Seeds Possesses lectin Activity and has a Highly Similar Vegetatively Expressed Wound-Inducible Counterpart

Authors


  • Note. The nucleotide sequence data presented here has been deposited with the EMBL database and are available under accession number Y09437.

J. Taipalensuu, Uppsala Genetic Center, Department of Cell Research, Swedish University of Agricultural Sciences, Box 7055, S-750 07 Sweden
Fax:46 18 673320.

Abstract

This communication demonstrates that proteins in the family of myrosinase-binding proteins (MBP) present in seeds of Brassica napus possess lectin activity, binding most efficiently to p-aminophenyl α L-D-mannopyranoside–agarose, and to some extent to N-acetylglucosamine–agarose. A cDNA encoding a vegetatively expressed, wound-inducible counterpart to these seed MBP was isolated and characterised. Upon wounding, this MBP transcript accumulated in old and young leaves, and was systemically expressed in the young plant. Additionally, the wound-induced MBP transcript increased in abundance after treating the young plants with methyl jasmonate (MeJA), jasmonic acid (JA) or abscisic acid (ABA), and to some extent in response to the ethylene precursor 1-aminocyclopropane-1-carboxylic acid. Expression induced by wounding, ABA or JA was antagonised by simultaneous feeding of the plants with salicylic acid. MBP polypeptides accumulated in MeJA-treated plants. The myrosinases redistributed from the soluble fraction into the insoluble fraction of a tissue extract after induction. The most abundant MBP (94 kDa) partitioned in the insoluble fraction, while two larger MBP (103 kDa and 108 kDa) were present only in the soluble fraction of extracts obtained from the control or MeJA-treated plant tissues.

Abbreviations
ABA

abscisic acid

ACC

l-aminocyclopropane-lcarboxylic acid

JA

jasmonic acid

MeJA

methyl jasmonate

MAP

myrosinase-associated protein

MBP

myrosinase-binding protein

SA

salicylic acid

Ancillary