Plants host a diverse microbiome and differentially react to the fungal species living as endophytes or around their roots through emission of volatiles. Here, using divided Petri plates for ...Arabidopsis‐T. atroviride co‐cultivation, we show that fungal volatiles increase endogenous sugar levels in shoots, roots and root exudates, which improve Arabidopsis root growth and branching and strengthen the symbiosis. Tissue‐specific expression of three sucrose phosphate synthase‐encoding genes (AtSPS1F, AtSPS2F and AtSPS3F), and AtSUC2 and SWEET transporters revealed that the gene expression signatures differ from those of the fungal pathogens Fusarium oxysporum and Alternaria alternata and that AtSUC2 is largely repressed either by increasing carbon availability or by perception of the fungal volatile 6‐pentyl‐2H‐pyran‐2‐one. Our data point to Trichoderma volatiles as chemical signatures for sugar biosynthesis and exudation and unveil specific modulation of a critical, long‐distance sucrose transporter in the plant.
T. atroviride volatiles trigger Arabidopsis biomass production and root branching by modulating genes encoding proteins for sugar biosynthesis and transport. A single volatile, namely 6‐pentyl‐2H‐pyran‐2‐one directly influences the major sucrose transporter AtSUC2, which may be critical for the development of the symbiosis.
SUMMARY
Members of the fungal genus Trichoderma stimulate growth and reinforce plant immunity. Nevertheless, how fungal signaling elements mediate the establishment of a successful Trichoderma−plant ...interaction is largely unknown. In this work, we analyzed growth, root architecture and defense in an Arabidopsis−Trichoderma co‐cultivation system, including the wild‐type (WT) strain of the fungus and mutants affected in NADPH oxidase. Global gene expression profiles were assessed in both the plant and the fungus during the establishment of the interaction. Trichoderma atroviride WT improved root branching and growth of seedling as previously reported. This effect diminished in co‐cultivation with the ∆nox1, ∆nox2 and ∆noxR null mutants. The data gathered of the Arabidopsis interaction with the ∆noxR strain showed that the seedlings had a heightened immune response linked to jasmonic acid in roots and shoots. In the fungus, we observed repression of genes involved in complex carbohydrate degradation in the presence of the plant before contact. However, in the absence of NoxR, such repression was lost, apparently due to a poor ability to adequately utilize simple carbon sources such as sucrose, a typical plant exudate. Our results unveiled the critical role played by the Trichoderma NoxR in the establishment of a fine‐tuned communication between the plant and the fungus even before physical contact. In this dialog, the fungus appears to respond to the plant by adjusting its metabolism, while in the plant, fungal perception determines a delicate growth−defense balance.
Significance Statement
A key question in biology is how organisms communicate with each other. Although significant advances have been made in understanding how plants recognize pathogens, still little is known about the recognition of beneficial organisms by plants. Our work demonstrates that reactive oxygen species produced by the symbiotic fungus Trichoderma are key to the establishment of its interaction with plants, and thus provides important clues for understanding the dialog that takes place between a plant and a beneficial microorganism.
Summary
Fruit development has been central in the evolution and domestication of flowering plants. In common bean (Phaseolus vulgaris), the principal global grain legume staple, two main production ...categories are distinguished by fibre deposition in pods: dry beans, with fibrous, stringy pods; and stringless snap/green beans, with reduced fibre deposition, which frequently revert to the ancestral stringy state. Here, we identify genetic and developmental patterns associated with pod fibre deposition.
Transcriptional, anatomical, epigenetic and genetic regulation of pod strings were explored through RNA‐seq, RT‐qPCR, fluorescence microscopy, bisulfite sequencing and whole‐genome sequencing.
Overexpression of the INDEHISCENT (‘PvIND’) orthologue was observed in stringless types compared with isogenic stringy lines, associated with overspecification of weak dehiscence‐zone cells throughout the pod vascular sheath. No differences in DNA methylation were correlated with this phenotype. Nonstringy varieties showed a tandemly direct duplicated PvIND and a Ty1‐copia retrotransposon inserted between the two repeats. These sequence features are lost during pod reversion and are predictive of pod phenotype in diverse materials, supporting their role in PvIND overexpression and reversible string phenotype.
Our results give insight into reversible gain‐of‐function mutations and possible genetic solutions to the reversion problem, of considerable economic value for green bean production.
Filamentous fungi constitute a large group of eukaryotic microorganisms that grow by forming simple tube-like hyphae that are capable of differentiating into more-complex morphological structures and ...distinct cell types. Hyphae form filamentous networks by extending at their tips while branching in subapical regions. Rapid tip elongation requires massive membrane insertion and extension of the rigid chitin-containing cell wall. This process is sustained by a continuous flow of secretory vesicles that depends on the coordinated action of the microtubule and actin cytoskeletons and the corresponding motors and associated proteins. Vesicles transport cell wall-synthesizing enzymes and accumulate in a special structure, the Spitzenkörper, before traveling further and fusing with the tip membrane. The place of vesicle fusion and growth direction are enabled and defined by the position of the Spitzenkörper, the so-called cell end markers, and other proteins involved in the exocytic process. Also important for tip extension is membrane recycling by endocytosis via early endosomes, which function as multipurpose transport vehicles for mRNA, septins, ribosomes, and peroxisomes. Cell integrity, hyphal branching, and morphogenesis are all processes that are largely dependent on vesicle and cytoskeleton dynamics. When hyphae differentiate structures for asexual or sexual reproduction or to mediate interspecies interactions, the hyphal basic cellular machinery may be reprogrammed through the synthesis of new proteins and/or the modification of protein activity. Although some transcriptional networks involved in such reprogramming of hyphae are well studied in several model filamentous fungi, clear connections between these networks and known determinants of hyphal morphogenesis are yet to be established.
Summary
Filamentous fungi respond to a variety of environmental signals. One of them is light, providing critical information about orientation, or impending stress. Cells of filamentous fungi appear ...to sense blue light through a unique transcription factor that has a flavin chromophore and activates its targets in a light‐dependent manner, the white collar (WC) complex. Fungal photophysiology, though, predicted a greater complexity of responses to the whole visible spectrum. The rapidly growing fungal genome database provides candidates to explain how fungi see not only blue, but also near‐UV, green and red light. At the same time, there are surprises in the genomes, including photoreceptors for which there are no obvious photoresponses. Linking these genes and their functions will help understand how a list of only a few biological chromophores accounts for such a diversity of responses. At the same time, deeper mechanistic understanding of how the WC complex functions will lead to fundamental insights at the point where the environment impinges, in this case in the form of photons, on the transcriptional machinery of the cell.
A conserved injury-defense mechanism is present in plants and animals, in which the production of reactive oxygen species (ROS) and lipid metabolism are essential to the response. Here, we describe ...that in the filamentous fungus Trichoderma atroviride , injury results in the formation of asexual reproduction structures restricted to regenerating cells. High-throughput RNA-seq analyses of the response to injury in T. atroviride suggested an oxidative response and activation of calcium-signaling pathways, as well as the participation of lipid metabolism, in this phenomenon. Gene-replacement experiments demonstrated that injury triggers NADPH oxidase (Nox)–dependent ROS production and that Nox1 and NoxR are essential for asexual development in response to damage. We further provide evidence of H ₂O ₂ and oxylipin production that, as in plants and animals, may act as signal molecules in response to injury in fungi, suggesting that the three kingdoms share a conserved defense-response mechanism.
Trichoderma research in the genome era Mukherjee, Prasun K; Horwitz, Benjamin A; Herrera-Estrella, Alfredo ...
Annual review of phytopathology,
01/2013, Letnik:
51
Journal Article
Recenzirano
Trichoderma species are widely used in agriculture and industry as biopesticides and sources of enzymes, respectively. These fungi reproduce asexually by production of conidia and chlamydospores and ...in wild habitats by ascospores. Trichoderma species are efficient mycoparasites and prolific producers of secondary metabolites, some of which have clinical importance. However, the ecological or biological significance of this metabolite diversity is sorely lagging behind the chemical significance. Many strains produce elicitors and induce resistance in plants through colonization of roots. Seven species have now been sequenced. Comparison of a primarily saprophytic species with two mycoparasitic species has provided striking contrasts and has established that mycoparasitism is an ancestral trait of this genus. Among the interesting outcomes of genome comparison is the discovery of a vast repertoire of secondary metabolism pathways and of numerous small cysteine-rich secreted proteins. Genomics has also facilitated investigation of sexual crossing in Trichoderma reesei, suggesting the possibility of strain improvement through hybridization.
Species belonging to the genus Trichoderma are free-living fungi common in soil and root ecosystems, and have a broad range of uses in industry and agricultural biotechnology. Some species of the ...genus are widely used biocontrol agents, and their success is in part due to mycoparasitism, a lifestyle in which one fungus is parasitic on another. In addition Trichoderma species have been found to elicit plant defence responses and to stimulate plant growth. In order to survive and spread, Trichoderma switches from vegetative to reproductive development, and has evolved with several sophisticated molecular mechanisms to this end. Asexual development (conidiation) is induced by light and mechanical injury, although the effects of these inducers are influenced by environmental conditions, such as nutrient status and pH. A current appreciation of the links between the molecular participants is presented in this review. The photoreceptor complex BLR-1/BLR-2, ENVOY, VELVET, and NADPH oxidases have been suggested as key participants in this process. In concert with these elements, conserved signalling pathways, such as those involving heterotrimeric G proteins, mitogen-activated protein kinases (MAPKs) and cAMP-dependent protein kinase A (cAMP-PKA) are involved in this molecular orchestration. Finally, recent comparative and functional genomics analyses allow a comparison of the machinery involved in conidiophore development in model systems with that present in Trichoderma and a model to be proposed for the key factors involved in the development of these structures.
Trichoderma is a genus of common filamentous fungi that display a remarkable range of lifestyles and interactions with other fungi, animals and plants. Because of their ability to antagonize ...plant-pathogenic fungi and to stimulate plant growth and defence responses, some Trichoderma strains are used for biological control of plant diseases. In this Review, we discuss recent advances in molecular ecology and genomics which indicate that the interactions of Trichoderma spp. with animals and plants may have evolved as a result of saprotrophy on fungal biomass (mycotrophy) and various forms of parasitism on other fungi (mycoparasitism), combined with broad environmental opportunism.
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