Molecular Plant-microbe Interactions 

About: Molecular Plant-microbe Interactions is an academic journal published by American Phytopathological Society. The journal publishes majorly in the area(s): Gene & Mutant. It has an ISSN identifier of 0894-0282. It is also open access. Over the lifetime, 4249 publications have been published receiving 294143 citations. The journal is also known as: MPMI.

Priming: Getting Ready for Battle

Abstract: Infection of plants by necrotizing pathogens or colonization of plant roots with certain beneficial microbes causes the induction of a unique physiological state called "priming." The primed state can also be induced by treatment of plants with various natural and synthetic compounds. Primed plants display either faster, stronger, or both activation of the various cellular defense responses that are induced following attack by either pathogens or insects or in response to abiotic stress. Although the phenomenon has been known for decades, most progress in our understanding of priming has been made over the past few years. Here, we summarize the current knowledge of priming in various induced-resistance phenomena in plants.

Bacterial Endophytes and Their Interactions with Hosts

Abstract: Recent molecular studies on endophytic bacterial diversity have revealed a large richness of species. Endophytes promote plant growth and yield, suppress pathogens, may help to remove contaminants, solubilize phosphate, or contribute assimilable nitrogen to plants. Some endophytes are seed-borne, but others have mechanisms to colonize the plants that are being studied. Bacterial mutants unable to produce secreted proteins are impaired in the colonization process. Plant genes expressed in the presence of endophytes provide clues as to the effects of endophytes in plants. Molecular analysis showed that plant defense responses limit bacterial populations inside plants. Some human pathogens, such as Salmonella spp., have been found as endophytes, and these bacteria are not removed by disinfection procedures that eliminate superficially occurring bacteria. Delivery of endo-phytes to the environment or agricultural fields should be carefully evaluated to avoid introducing pathogens.

Signal signature and transcriptome changes of Arabidopsis during pathogen and insect attack.

Abstract: Plant defenses against pathogens and insects are regulated differentially by cross-communicating signaling pathways in which salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) play key roles. To understand how plants integrate pathogen- and insect-induced signals into specific defense responses, we monitored the dynamics of SA, JA, and ET signaling in Arabidopsis after attack by a set of microbial pathogens and herbivorous insects with different modes of attack. Arabidopsis plants were exposed to a pathogenic leaf bacterium (Pseudomonas syringae pv. tomato), a pathogenic leaf fungus (Alternaria brassicicola), tissuechewing caterpillars (Pieris rapae), cell-content-feeding thrips (Frankliniella occidentalis), or phloem-feeding aphids (Myzus persicae). Monitoring the signal signature in each plant-attacker combination showed that the kinetics of SA, JA, and ET production varies greatly in both quantity and timing. Analysis of global gene expression profiles demonstrated that the signal signature characteristic of each Arabidopsis-attacker combination is orchestrated into a surprisingly complex set of transcriptional alterations in which, in all cases, stress-related genes are overrepresented. Comparison of the transcript profiles revealed that consistent changes induced by pathogens and insects with very different modes of attack can show considerable overlap. Of all consistent changes induced by A. brassicicola, Pieris rapae, and F. occidentalis, more than 50% also were induced consistently by P. syringae. Notably, although these four attackers all stimulated JA biosynthesis, the majority of the changes in JA-responsive gene expression were attacker specific. All together, our study shows that SA, JA, and ET play a primary role in the orchestration of the plant’s defense response, but other regulatory mechanisms, such as pathway cross-talk or additional attacker-induced signals, eventually shape the highly complex attacker-specific defense response.

Rhizoremediation: A Beneficial Plant-Microbe Interaction

Abstract: Worldwide, contamination of soil and ground water is a severe problem. The negative effects of pollutants on the environment and on human health are diverse and depend on the nature of the pollution. The search for alternative methods for excavation and incineration to clean polluted sites resulted in the application of bioremediation techniques. In this review, we describe some generally accepted bioremediation tools and subsequently focus on the combination of two approaches, phytoremediation and bioaugmentation, resulting in rhizoremediation. During rhizoremediation, exudates derived from the plant can help to stimulate the survival and action of bacteria, which subsequently results in a more efficient degradation of pollutants. The root system of plants can help to spread bacteria through soil and help to penetrate otherwise impermeable soil layers. The inoculation of pollutant-degrading bacteria on plant seed can be an important additive to improve the efficiency of phytoremediation or bioaugmentation.

Reduced virulence of Gibberella zeae caused by disruption of a trichothecene toxin biosynthetic gene

Abstract: The production of trichothecene mycotoxins by some plant pathogenic species of Fusarium is thought to contribute to their virulence. Gibberella zeae (F. graminearum) is an important cereal pathogen that produces the trichothecene deoxynivalenol. To determine if trichothecene production contributes to the virulence of G. zeae, we generated trichothecene-deficient mutants of the fungus by gene disruption. The disrupted gene, Tri5, encodes the enzyme trichodiene synthase, which catalyzes the first step in trichothecene biosynthesis. To disrupt Tri5, G. zeae was transformed with a plasmid carrying a doubly truncated copy of the Tri5 coding region interrupted by a hygromycin B resistance gene. Tri5- transformants were selected by screening for the inability to produce trichothecenes and by Southern blot analysis. Tri5- strains exhibited reduced virulence on seedlings of Wheaton wheat and common winter rye, but wild-type virulence on seedlings of Golden Bantam maize. On Caldwell and Marshall wheat and Porter oat seedlings, Tri5- strains were inconsistent in causing less disease than their wild-type progenitor strain. Head blight developed more slowly on Wheaton when inoculated with Tri5- mutants than when inoculated with wild-type strains. These results suggest that trichothecene production contributes to the virulence of G. zeae on some hosts.