The hepta-β-glucoside elicitor-binding proteins from legumes represent a putative receptor family

The ability of legumes to recognize and respond to β-glucan elicitors by synthesizing phytoalexins is consistent with the existence of a membrane-bound β-glucan-binding site. Related proteins of approximately 75 kDa and the corresponding mRNAs were detected in various species of legumes which respond to beta-glucans. The cDNAs for the beta-glucan-binding proteins of bean and soybean were cloned. The deduced 75-kDa proteins are predominantly hydrophilic and constitute a unique class of glucan-binding proteins with no currently recognizable functional domains. Heterologous expression of the soybean beta-glucan-binding protein in tomato cells resulted in the generation of a high-affinity binding site for the elicitor-active hepta-β-glucoside conjugate (K-d = 4.5 nM). Ligand competition experiments with the recombinant binding sites demonstrated similar ligand specificities when compared with soybean. In both soybean and transgenic tomato, membrane-bound, active forms of the glucan-binding proteins coexist with immunologically detectable, soluble but inactive forms of the proteins. Reconstitution of a soluble protein fraction into lipid vesicles regained beta-glucoside-binding activity but with lower affinity (K-d = 130 nM). We conclude that the beta-glucan elicitor receptors of legumes are composed of the 75 kDa glucan-binding proteins as the critical components for ligand-recognition, and of an as yet unknown membrane anchor constituting the plasma membrane-associated receptor complex

MpTCP1 controls cell proliferation and redox processes in Marchantia polymorpha

TCP transcription factors are key regulators of angiosperm cell proliferation processes. It is unknown whether their regulatory growth capacities are conserved across land plants, which we examined in liverworts, one of the earliest diverging land plant lineages. We generated knockout mutants for MpTCP1, the single TCP‐P clade gene in Marchantia polymorpha, and characterized its function conducting cell proliferation and morphological analyses as well as mRNA expression, transcriptome, chemical and DNA binding studies. Mptcp1ge lines show a reduced vegetative thallus growth and extra tissue formation in female reproductive structures. Additionally, mutant plants reveal increased H2O2 levels and an enhanced pigmentation in the thallus caused by formation of secondary metabolites, such as aminochromes. MpTCP1 proteins interact redox‐dependently with DNA and regulate the expression of a comprehensive redox network, comprising enzymes involved in H2O2 metabolism. MpTCP1 regulates Marchantia growth context‐dependently. Redox sensitivity of the DNA binding capacity of MpTCP1 proteins provides a mechanism to respond to altered redox conditions. Our data suggest that MpTCP1 activity could thereby have contributed to diversification of land plant morphologies and to adaptations to abiotic and biotic challenges, experienced by liverworts during early land plant colonization

A spotlight on prey-induced metabolite dynamics in sundew. A commentary on: 'Metabolomic analysis reveals reliance on secondary plant metabolites to facilitate carnivory in the Cape sundew, Drosera capensis

This article comments on: Christopher R. Hatcher, Ulf Sommer, Liam M. Heaney and Jonathan Millett, Metabolomic analysis reveals reliance on secondary plant metabolites to facilitate carnivory in the Cape sundew, Drosera capensis, Annals of Botany Volume 128, Issue 3, 26 August 2021, Pages 301–314, https://doi.org/10.1093/aob/mcab06

Plumbagin, a potent naphthoquinone from Nepenthes plants with growth inhibiting and larvicidal activities

Some plant species are less susceptible to herbivore infestation than others. The reason for this is often unknown in detail but is very likely due to an efficient composition of secondary plant metabolites. Strikingly, carnivorous plants of the genus Nepenthes show extremely less herbivory both in the field and in green house. In order to identify the basis for the efficient defense against herbivorous insects in Nepenthes, we performed bioassays using larvae of the generalist lepidopteran herbivore, Spodoptera littoralis. Larvae fed with different tissues from Nepenthes x ventrata grew significantly less when feeding on a diet containing leaf tissue compared with pitcher-trap tissue. As dominating metabolite in Nepenthes tissues, we identified a naphthoquinone, plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone). When plumbagin was added at different concentrations to the diet of S. littoralis larvae, an EC50 value for larval growth inhibition was determined with 226.5 µg g−1 diet. To further determine the concentration causing higher larval mortality, sweet potato leaf discs were covered with increasing plumbagin concentrations in no-choice-assays; a higher mortality of the larvae was found beyond 60 µg plumbagin per leaf, corresponding to 750 µg g−1. Plant-derived insecticides have long been proposed as alternatives for pest management; plumbagin and derivatives might be such promising environmentally friendly candidates