caa a22 4500 477100031 CHVBK 20180405111538.0 cr unu---uuuuu 170330e19960901xx s 000 0 eng 10.1007/BF00196654 doi (NATIONALLICENCE)springer-10.1007/BF00196654 High-affinity binding of fungal β-glucan elicitors to cell membranes of species of the plant family Fabaceae [Elektronische Daten] [Eric Cosio, Markus Feger, Connie Miller, Luis Antelo, Jürgen Ebel] Microsomal preparations of six species of the plant family Fabaceae were screened for high-affinity binding of branched (1 → 3), (1 → 6)-β-glucans. Oligoglucosides of this type are specific elicitors of phytoalexin accumulation in soybean (Glycine max L.), a member of this family. The species studied were alfalfa (Medicago sativa L.), broadbean (Vicia faba L.), chickpea (Cicer arietinum L.), french bean (Phaseolus vulgaris L.), pea (Pisum sativum L.), and white lupin (Lupinus albus L.). A 125I-labeled 4-(2-aminophenyl)ethylamine conjugate of a (1 → 3), (1 → 6)-β-glucan fraction with an average degree of polymerization (DP) of 18, obtained from mycelial walls of Phytophthora sojae, was used as radioligand for initial screening. The structural complexity of this fraction allowed the identification of binding sites with affinities for isomeric structures other than the (1 → 3), (1 → 6) hepta-β-glucoside for which soybean binding sites display highest affinity. Radioligand competition experiments against unlabeled fungal β-glucan resulted in the identification of high-affinity binding in alfalfa, bean, lupin, and pea. Half-maximal competition concentrations (IC50) for fungal β-glucan in these species were between 5 and 30 nM. Pseudoheterologous radioligand competition by unlabeled hepta-β-glucoside showed that for alfalfa, lupin and pea the IC50 values for this structure (4 to 16 nM) were similar to those of soybean (7.7 nM). Bean microsomes, however, displayed an IC50 significantly higher than soybean (68 nM) suggesting that the structural motif recognized by its binding sites is not identical to that of soybean or the other three species. Radioligand saturation assays with alfalfa, lupin and pea microsomes using an 125I-labeled aminophenylethylamine hepta-β-glucoside conjugate gave dissociation constants (Kd) of 5.3, 3.7, and 1.8 nM, respectively. The affinity of these sites for hepta-β glucoside was in the same range as that of soybean (Kd 1-3 nM), whereas the affinity of the binding sites of bean for the same ligand was significantly lower (Kd = 33 nM). Good correlation was found between the presence of high-affinity binding and the accumulation of isoflavonoid phytoalexins in roots of alfalfa, bean, chickpea and pea seedlings after exposure to fungal β-glucan. Lupin displayed a strong wound-induced accumulation of prenylated isoflavones which was independent of the presence of β-glucan, making it impossible to determine phytoalexin induction in response to elicitor. No specific binding or phytoalexin accumulation in response to β glucans was observed in broadbean. This is the first report on the existence of possibly homologous elicitor-binding sites within a plant taxonomic family and may provide preliminary evidence for putative evolutionary relationships in pathogen perception mechanisms in plants. Springer-Verlag, 1996 Fabaceae nationallicence β-Glucan elicitor nationallicence Pathogen perception nationallicence Phytoalexin nationallicence DP : degree of polymerization nationallicence EC50 : concentration of elicitor necessary to obtain a half-maximal biological response nationallicence HG : synthetic (1 → 3), (1 → 6)-hepta-β-glucoside phytoalexin elicitor nationallicence HG-APEA : 1-[4-(2-aminophenyl)ethylamino-1-hexaglucosyl]deoxyglucitol nationallicence IC50 : ligand concentration necessary to obtain half-maximal displacement of radioligand in competition binding assays nationallicence Kd : dissociation constant nationallicence OS : branched (1 → 3), (1 → 6)-β-glucan obtained by hydrolysis of mycelial walls of Phytophthora sojae nationallicence OS-APEA : 1-[4-(2-armnophenyl)ethylamino-1-oligoglucosyl]deoxyglucitol conjugate of OS nationallicence Cosio Eric Centre Nacional de Biotecnologia, C.S.I.C., Campus Universidad Autonoma, E-28049, Madrid, Spain aut Feger Markus Botanisches Institut der Universität, Menzinger Str. 67, D-80638, München, Germany aut Miller Connie Centre Nacional de Biotecnologia, C.S.I.C., Campus Universidad Autonoma, E-28049, Madrid, Spain aut Antelo Luis Centre Nacional de Biotecnologia, C.S.I.C., Campus Universidad Autonoma, E-28049, Madrid, Spain aut Ebel Jürgen Botanisches Institut der Universität, Menzinger Str. 67, D-80638, München, Germany aut Planta Springer-Verlag 200/1(1996-09-01), 92-99 0032-0935 200:1<92 1996 200 425 https://doi.org/10.1007/BF00196654 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00196654 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Cosio Eric Centre Nacional de Biotecnologia, C.S.I.C., Campus Universidad Autonoma, E-28049, Madrid, Spain aut NATIONALLICENCE 700 1- Feger Markus Botanisches Institut der Universität, Menzinger Str. 67, D-80638, München, Germany aut NATIONALLICENCE 700 1- Miller Connie Centre Nacional de Biotecnologia, C.S.I.C., Campus Universidad Autonoma, E-28049, Madrid, Spain aut NATIONALLICENCE 700 1- Antelo Luis Centre Nacional de Biotecnologia, C.S.I.C., Campus Universidad Autonoma, E-28049, Madrid, Spain aut NATIONALLICENCE 700 1- Ebel Jürgen Botanisches Institut der Universität, Menzinger Str. 67, D-80638, München, Germany aut NATIONALLICENCE 773 0- Planta Springer-Verlag 200/1(1996-09-01), 92-99 0032-0935 200:1<92 1996 200 425 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer