Thionins from barley

Girbes, L. Citores, and F. Soriano. Primary structure of omega-hordothionin, a member of a novel family of thionins from barley endosperm, and its inhibi- HV028 tion of protein synthesis in eucaryotic and procaryotic cell-free system. Eur J Biochem 1996 239(1) 67-73. 

Northern-blot analysis with specific oligonucleotide primers against two LOX isoforms from barley (LOX-B - LOX-C, Fig. 1) reveals a different response of these forms for the tested incubation regimes. JIP-23 and thionin were taken as standards for JIP induction by JM, Both forms were induced by JM and sorbitol, and their transcripts could not be detected in untreated or with water incubated leaves. Whereas LOXb showed no differences between the two induction protocols, exhibited LOXc a different response to osmotic stress or incubation with JM. 

Plant defensins are cystine-rich, cationic peptides ranging in size from 45 to 54 amino acids, of which eight are cysteine. They were first discovered in wheat and barley ° and were proposed to form a novel subclass of thionins, the 7-thionins. As it became clear that they closely resemble mammalian and insect defensins in primary and secondary structure, the term plant defensins was introduced to describe these peptides. It is generally assumed that all plants express plant defensins " and that they are expressed in a wide range of plant tissue, that is, leaves, floral tissue,tubers,bark, root, pods, and seeds,with seeds in particular being from where most plant defensins have been isolated. ... 

Figure 1. LOX transcripts during treatment of leaf segments with JM or sorbitol RNA gel blots hybridized with barley cDNAs coding for LOXb and c (LOX derived oligonucleotide primers from arabidopsis [2] were used in PCR reaction with different barley genomic DNAs as templates to generate specific probes. The resulting clones b, and c correspond to LOXb and LOXc fiom barley pers. communication J. Rouster), JIP-23, and thionin according to published protocols [1].

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