Plant-microbe interactions: Mining heritable root-associated microbiota across environments.

The root-associated microbiota represents an untapped reservoir of beneficial functions for plants. A new study begins unravelling the host genetic determinants governing these interactions across environments, which will be a key step towards the development of novel climate-smart crops.

Engineering the Crop Microbiota Through Host Genetics.

The microbiota populating the plant-soil continuum defines an untapped resource for sustainable crop production. The host plant is a driver for the taxonomic composition and function of these microbial communities. In this review, we illustrate how the host genetic determinants of the microbiota have been shaped by plant domestication and crop diversification.

Defining Composition and Function of the Rhizosphere Microbiota of Barley Genotypes Exposed to Growth-Limiting Nitrogen Supplies.

The microbiota populating the rhizosphere, the interface between roots and soil, can modulate plant growth, development, and health. These microbial communities are not stochastically assembled from the surrounding soil, but their composition and putative function are controlled, at least partially, by the host plant. Here, we use the staple cereal barley as a model to gain novel insights into the impact of differential applications of nitrogen, a rate-limiting step for global crop production, on the host genetic control of the rhizosphere microbiota.

Identifying plant genes shaping microbiota composition in the barley rhizosphere.

A prerequisite to exploiting soil microbes for sustainable crop production is the identification of the plant genes shaping microbiota composition in the rhizosphere, the interface between roots and soil. Here, we use metagenomics information as an external quantitative phenotype to map the host genetic determinants of the rhizosphere microbiota in wild and domesticated genotypes of barley, the fourth most cultivated cereal globally. We identify a small number of loci with a major effect on the composition of rhizosphere communities.

Applications of the indole-alkaloid gramine modulate the assembly of individual members of the barley rhizosphere microbiota.

Microbial communities proliferating at the root-soil interface, collectively referred to as the rhizosphere microbiota, represent an untapped beneficial resource for plant growth, development and health. Integral to a rational manipulation of the microbiota for sustainable agriculture is the identification of the molecular determinants of these communities. In plants, biosynthesis of allelochemicals is centre stage in defining inter-organismal relationships in the environment.

Plant resistance in different cell layers affects aphid probing and feeding behaviour during non-host and poor-host interactions.

Aphids are phloem-feeding insects that cause economic losses to crops globally. Whilst aphid interactions with susceptible plants and partially resistant genotypes have been well characterized, the interactions between aphids and non-host species are not well understood. Unravelling these non-host interactions can identify the mechanisms which contribute to plant resistance.

An aphid effector promotes barley susceptibility through suppression of defence gene expression.

Aphids secrete diverse repertoires of effectors into their hosts to promote the infestation process. While 'omics' approaches facilitated the identification and comparison of effector repertoires from a number of aphid species, the functional characterization of these proteins has been limited to dicot (model) plants. The bird cherry-oat aphid Rhopalosiphum padi is a pest of cereal crops, including barley.

Tracing the evolutionary routes of plant-microbiota interactions.

The microbiota thriving at the root-soil interface plays a crucial role in supporting plant growth, development and health. The interactions between plant and soil microbes can be traced back to the initial plant's colonisation of dry lands. Understanding the evolutionary drivers of these interactions will be key to re-wire them for the benefit of mankind.

Shared Transcriptional Control and Disparate Gain and Loss of Aphid Parasitism Genes.

Aphids are a diverse group of taxa that contain agronomically important species, which vary in their host range and ability to infest crop plants. The genome evolution underlying agriculturally important aphid traits is not well understood. We generated draft genome assemblies for two aphid species: Myzus cerasi (black cherry aphid) and the cereal specialist Rhopalosiphum padi.

An Aphid Effector Targets Trafficking Protein VPS52 in a Host-Specific Manner to Promote Virulence.

Plant- and animal-feeding insects secrete saliva inside their hosts, containing effectors, which may promote nutrient release and suppress immunity. Although for plant pathogenic microbes it is well established that effectors target host proteins to modulate host cell processes and promote disease, the host cell targets of herbivorous insects remain elusive. Here, we show that the existing plant pathogenic microbe effector paradigm can be extended to herbivorous insects in that effector-target interactions inside host cells modify critical host processes to promote plant susceptibility.

Plant immunity in plant-aphid interactions.

Aphids are economically important pests that cause extensive feeding damage and transmit viruses. While some species have a broad host range and cause damage to a variety of crops, others are restricted to only closely related plant species. While probing and feeding aphids secrete saliva, containing effectors, into their hosts to manipulate host cell processes and promote infestation.