Evolutionary trade-offs at the Arabidopsis WRR4A resistance locus underpin alternate Albugo candida recognition specificities

The oomycete Albugo candida causes white rust of Brassicaceae, including vegetable and oilseed crops, and wild relatives such as Arabidopsis thaliana. Novel White Rust Resistance (WRR)-genes from Arabidopsis enable new insights into plant/parasite co-evolution. WRR4A from Arabidopsis accession Col-0 provides resistance to many but not all white rust races, and encodes a nucleotide-binding (NB), leucine-rich repeat (LRR) (NLR) immune receptor protein. Col-0 WRR4A resistance is broken by a Col-0-virulent isolate of A. candida race 4 (AcEx1). We identified an allele of WRR4A in Arabidopsis accession Oy-0 and other accessions that confers full resistance to AcEx1. WRR4AOy-0 carries a C-terminal extension required for recognition of AcEx1, but reduces recognition of several effectors recognized by the WRR4A_Col-0 allele. WRR4A_Oy-0 confers full resistance to AcEx1 when expressed as a transgene in the oilseed crop Camelina sativa.

The quasi-universality of nestedness in the structure of quantitative plant-parasite interactions

Understanding the relationships between host range and pathogenicity for parasites, and between the efficiency and scope of immunity for hosts are essential to implement efficient disease control strategies. In the case of plant parasites, most studies have focused on describing qualitative interactions and a variety of genetic and evolutionary models has been proposed in this context. Although plant quantitative resistance benefits from advantages in terms of durability, we presently lack models that account for quantitative interactions between plants and their parasites and the evolution of these interactions. Nestedness and modularity are important features to unravel the overall structure of host-parasite interaction matrices. Here, we analysed these two features on 32 matrices of quantitative pathogenicity trait data gathered from 15 plant-parasite pathosystems consisting of either annual or perennial plants along with fungi or oomycetes, bacteria, nematodes, insects and viruses. The performance of several nestedness and modularity algorithms was evaluated through a simulation approach, which helped interpretation of the results. We observed significant modularity in only six of the 32 matrices, with two or three modules detected. For three of these matrices, modules could be related to resistance quantitative trait loci present in the host. In contrast, we found high and significant nestedness in 30 of the 32 matrices. Nestedness was linked to other properties of plant-parasite interactions. First, pathogenicity trait values were explained in majority by a parasite strain effect and a plant accession effect, with no parasite-plant interaction term. Second, correlations between the efficiency and scope of the resistance of plant genotypes, and between the host range breadth and pathogenicity level of parasite strains were overall positive. This latter result questions the efficiency of strategies based on the deployment of several genetically-differentiated cultivars of a given crop species in the case of quantitative plant immunity.

A multi-kingdom metabarcoding study on cattle grazing Alpine pastures discloses intra-seasonal shifts in plant selection and faecal microbiota

Diet selection by grazing livestock may affect animal performance as well as the biodiversity of grazed areas. Recent DNA barcoding techniques allow to assess dietary plant composition in faecal samples, which may be additionally integrated by the description of gut microbiota. In this high throughput metabarcoding study, we investigated the diversity of plant, fungal and bacterial taxa in faecal samples of lactating cows of two breeds grazing an Alpine semi-natural grassland during summer. The estimated plant composition of the diet comprised 67 genera and 39 species, which varied remarkably during summer, suggesting a decline of the diet forage value with the advancing of the vegetative season. The fungal community included Neocallimastigomycota gut symbionts, but also Ascomycota and Basidiomycota plant parasite and coprophilous taxa, likely ingested during grazing. The proportion of ingested fungi was remarkably higher than in other studies, and varied during summer, although less than that observed for plants. Some variation related to breed was also detected. The gut bacterial taxa remained stable through the summer but displayed a breed-specific composition. The study provided insights in the reciprocal organisms’ interactions affecting, and being affected by, the foraging behaviour: plants showed a high temporal variation, fungi a smaller one, while bacteria had practically none; conversely, the same kingdoms showed the opposite gradient of variation as respect to the animal host breed, as bacteria revealed to be the group mostly characterized by host-specificity.

The Isolation and Identification of Active Compound of Dendrophthoe praelonga (Blume) Miq. Extract Against Breast Cancer Cells (MCF-7)

Petai mistletoe (Dendrophthoe praelonga (Blume) Miq) is semi-parasitic plant. Parasite plant has been used traditionally in Indonesia to prevent or treat degenerative diseases, such as cancer. The purpose of this study was to indentify anticancer compound of petai mistletoe leaves extract and to examine its antioxidant activity (based on DPPH method) and cytotoxic activity on breast cancer (MCF-7) cell lines in vitro using Alamar blue method. This research aims to isolating, characterize, determine antioxidant activity and cytotoxic activity. Separation was conducting column chromathography and characterize was conducted using TLC, FT-IR, LC-MS and NMR-1D. From the result obtained, the isolated compound is flavonol quercetine (3,3,7,3’,4’ pethahydroxyflavone) which active antioxidant with IC50 value of 9.4 μg/mL and the value of cytotoxic activity with IC50 750.62 μg/mL

16S rRNA Gene Diversity of Bacterial Endophytes in Parasitic Cuscuta campestris and Its Helianthus annuus Host

ABSTRACT Here, we report the results of 16S rRNA gene amplicon sequencing of bacterial endophytes from parasitized and unparasitized samples of the common sunflower (Helianthus annuus) and samples of its associated plant parasite field dodder (Cuscuta campestris), collected from one location in Fresno County, California (August 2017).

The Influence of Acacia Parasite Filtrate as Bioinsecticide for Bagworms (Methane Plana)

Dendrophthoe pentandra is a plant parasite that can be detrimental to the host plant and attacks various types of trees, such as acacia. The purpose of this study was to examine the effects and determine the concentration of acacia parasite filtrate on bagworms. This research was an experimental study which used 0%, 20%, 40%, 60%, 80%, and 100% parasite filtrate concentrations. The study employed the Completely Randomized Design method with ANOVA as the method of analysis. Based on the results of phytochemical tests, the parasite filtrate contained alkaloids, flavonoids, saponins, triterpenoids, phenolics, and tannins. The ANOVA test results showed that the concentration of acacia parasite filtrate affected the mortality of the bagworms. Furthermore, based on Duncan's test, the most effective concentrations to be applied were 80%, 60%, and 100%.