Expression of genes encoding PR10 class patho genesis-related proteins is inhibited in yellow lupine root nodules

Pathogenesis-related proteins of the PR10 class have been found in many pla nt species, are induced under various stress conditions and act as common a llergens. Here we demonstrate the presence of two PR10 proteins in yellow l upine (Lupinus luteus L. cv. Ventus). Both 17 kDa proteins, referred to as LIPR10.1A and LLPR10.1B, are composed of 156 amino acids, and have 76% pari ties identity (91% similarity). Identity to homologues from other plants ra nges from 25 to 67% (46-82% similarity). Patterns of their expression in lu pine organs and tissues were investigated using Western blotting and immuno cytochemistry. Both proteins are constitutively expressed in roots, but exp ression is significantly decreased in young and mature root nodules (9-26 d ays post infection (dpi)), but not in senescent nodules (36 dpi). Immunocyt ochemical staining localised the proteins in the parenchymatous tissues of the root and senescent nodule, primarily in the cortex. The PR10 proteins w ere not detected in nodule bacteroid tissue. Expression in aerial parts of the plant is generally lower and only one of the proteins, LLPR10.1B, is ex pressed constitutively in the stem, leaf and petiole, while the other, L1PR 10.1A, is only present in the stem and is induced in senescent leaves. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.