H. Gagnon et al., PHYTOCHEMICAL AND IMMUNOCYTOCHEMICAL EVIDENCE FOR THE ACCUMULATION OF2'-HYDROXYLUPALBIGENIN IN LUPIN NODULES AND BACTEROIDS, Molecular plant-microbe interactions, 8(1), 1995, pp. 131-137
Symbiotic interaction between Rhizobium lupini and Lupinus albus promo
tes both qualitative and quantitative changes in the isoflavonoids of
root and nodule tissues, These changes were determined by high-pressur
e liquid chromatography and radiolabeling with L-[U-C-14]phenylalanine
, Root nodules from mature lupin plants accumulate prenylated derivati
ves of both genistein and 2'-hydroxygenistein, with the predominance o
f 2'-hydroxylupalbigenin, a diprenylated isoflavone. Immunogold locali
zation, using specific polyclonal immunoglobulin Gs, revealed an assoc
iation of 2'-hydroxylupalbigenin with the establishment of early symbi
otic structures, as well as with the bacteroids themselves, These resu
lts, together with the fact that prenylated isoflavonoids significantl
y reduce the in vitro growth rate of a number of Rhizobium species, su
ggest that 2'-hydroxylupalbigenin may be involved in the symbiotic ass
ociation of L, albus and R, lupini. This hypothesis is discussed in re
lation to the putative biological significance of prenylated isoflavon
oids.