Explore the vast range of titles available.

Dinoflagellates are a major cause of harmful algal blooms (HABs), with consequences for coastal marine ecosystem functioning and services. Alexandrìum fundyense (previously Alexandnum tamarense) is one of the most abundant and widespread toxigenic species in the temperate Northern and Southern Hemisphere and produces paralytic shellfish poisoning toxins as well as lytic allelochemical substances. These bioactive compounds may support the success of A. fundyense and its ability to form blooms. Here we investigate the impact of grazing on monoclonal and mixed set-ups of highly (Alex2) and moderately (Alex4) allelochemically active A. fundyense strains and a non-allelochemically active conspecific (Alex5) by the heterotrophic dinoflagellate Polykrikos kofoidii. While Alex4 and particularly Alex5 were strongly grazed by P. kofoidii when offered alone, both strains grew well in the mixed assemblages (Alex4 + Alex5 and Alex2 + Alex5). Hence, the allelochemical active strains facilitated growth of the non-active strain by protecting the population as a whole against grazing. Based on our results, we argue that facilitation among donai lineages within a species may partly explain the high genotypic and phenotypic diversity of Alexandrium populations. Populations of Alexandrium may comprise multiple cooperative traits that act in concert with intraspecific facilitation, and hence promote the success of this notorious HAB species.

Rice is a key crop for meeting the global food demand and ensuring food security. However, the crop has been facing great problems to combat the weed problem. Synthetic herbicides pose a severe threat to the long-term viability of agricultural output, agroecosystems, and human health. Allelochemicals, secondary metabolites of allelopathic plants, are a powerful tool for biological and eco-friendly weed management. The dynamics of weed species in various situations are determined by crop allelopathy. Phenolics and momilactones are the most common allelochemicals responsible for herbicidal effects in rice. The dispersion of allelochemicals is influenced not only by crop variety but also by climatic conditions. The most volatile chemicals, such as terpenoids, are usually emitted by crop plants in drought-stricken areas whereas the plants in humid zones release phytotoxins that are hydrophilic in nature, including phenolics, flavonoids, and alkaloids. The allelochemicals can disrupt the biochemical and physiological processes in weeds causing them to die finally. This study insight into the concepts of allelopathy and allelochemicals, types of allelochemicals, techniques of investigating allelopathic potential in rice, modes of action of allelochemicals, pathways of allelochemical production in plants, biosynthesis of allelochemicals in rice, factors influencing the production of allelochemicals in plants, genetical manipulation through breeding to develop allelopathic traits in rice, the significance of rice allelopathy in sustainable agriculture, etc. Understanding these biological phenomena may thus aid in the development of new and novel weed-control tactics while allowing farmers to manage weeds in an environmentally friendly manner.

Allelopathy is a common biological phenomenon by which one organism produces biochemicals that influence the growth, survival, development, and reproduction of other organisms. These biochemicals are known as allelochemicals and have beneficial or detrimental effects on target organisms. Plant allelopathy is one of the modes of interaction between receptor and donor plants and may exert either positive effects (e.g., for agricultural management, such as weed control, crop protection, or crop re-establishment) or negative effects (e.g., autotoxicity, soil sickness, or biological invasion). To ensure sustainable agricultural development, it is important to exploit cultivation systems that take advantage of the stimulatory/inhibitory influence of allelopathic plants to regulate plant growth and development and to avoid allelopathic autotoxicity. Allelochemicals can potentially be used as growth regulators, herbicides, insecticides, and antimicrobial crop protection products. Here, we reviewed the plant allelopathy management practices applied in agriculture and the underlying allelopathic mechanisms described in the literature. The major points addressed are as follows: (1) Description of management practices related to allelopathy and allelochemicals in agriculture. (2) Discussion of the progress regarding the mode of action of allelochemicals and the physiological mechanisms of allelopathy, consisting of the influence on cell micro- and ultra-structure, cell division and elongation, membrane permeability, oxidative and antioxidant systems, growth regulation systems, respiration, enzyme synthesis and metabolism, photosynthesis, mineral ion uptake, protein and nucleic acid synthesis. (3) Evaluation of the effect of ecological mechanisms exerted by allelopathy on microorganisms and the ecological environment. (4) Discussion of existing problems and proposal for future research directions in this field to provide a useful reference for future studies on plant allelopathy.

Microorganisms produce and excrete a versatile array of metabolites with different physico-chemical properties and biological activities. However, the ability of microorganisms to release volatile compounds has only attracted research attention in the past decade. Recent research has revealed that microbial volatiles are chemically very diverse and have important roles in distant interactions and communication. Microbial volatiles can diffuse fast in both gas and water phases, and thus can mediate swift chemical interactions. As well as constitutively emitted volatiles, microorganisms can emit induced volatiles that are triggered by biological interactions or environmental cues. In this Review, we highlight recent discoveries concerning microbial volatile compounds and their roles in intra-kingdom microbial interactions and inter-kingdom interactions with plants and insects. Furthermore, we indicate the potential biotechnological applications of microbial volatiles and discuss challenges and perspectives in this emerging research field.Microorganisms produce and excrete an array of metabolites with different physico-chemical properties and biological activities. In this Review, Garbeva and colleagues highlight recent discoveries concerning microbial volatile compounds and their roles in intra-kingdom and inter-kingdom communication, and discuss the potential biotechnological applications of microbial volatiles, as well as challenges and perspectives in this emerging research field.

Plants can produce and release allelochemicals to interfere with the establishment and growth of conspecific and interspecific plants. Such allelopathy is an important mediator among plant species in natural and managed ecosystems. This review focuses on allelopathy and allelochemicals in grasslands and forests. Allelopathy drives plant invasion, exacerbates grassland degradation and contributes to natural forest regeneration. Furthermore, autotoxicity (intraspecific allelopathy) frequently occurs in pastures and tree plantations. Various specialized metabolites, including phenolics, terpenoids and nitrogen-containing compounds from herbaceous and woody species are responsible for allelopathy in grasslands and forests. Terpenoids with a diversity of metabolites are qualitative allelochemicals occurring in annual grasslands, while phenolics with a few specialized metabolites are quantitative allelochemicals occurring in perennial forests. Importantly, allelochemicals mediate below-ground ecological interactions and plant–soil feedback, subsequently affecting the biodiversity, productivity and sustainability of grasslands and forests. Interestingly, allelopathic plants can discriminate the identity of neighbors via signaling chemicals, adjusting the production of allelochemicals. Therefore, allelochemicals and signaling chemicals synergistically interact to regulate interspecific and intraspecific interactions in grasslands and forests. Allelopathy and allelochemicals in grasslands and forests have provided fascinating insights into plant–plant interactions and their consequences for biodiversity, productivity and sustainability, contributing to our understanding of terrestrial ecosystems and global changes.

Arbuscular mycorrhizal fungi (AMF) can increase plant fitness under certain environmental conditions. Among the mechanisms that may drive this mutualism, the most studied is provisioning of nutrients by AMF in exchange for carbon from plant hosts. However, AMF may also provide a suite of non-nutritional benefits to plants including improved water uptake, disease resistance, plant chemical defense, soil aggregation, and allelochemical transport and protection. Here, we use a meta-analysis of 93 studies to assess the relative effect of AMF on nutritional and non-nutritional factors that may influence plant fitness. We find that the positive effects of AMF on soil aggregation, water flow and disease resistance are equal to the effect of AMF on plant nitrogen and phosphorus uptake. However, AMF had no effect on the uptake of other nutrients, plant water content, allelopathic transport or production of chemical defense compounds. We suggest future research directions, including experimentally assessing the relative contribution on plant fitness of AMF interactions by untangling the independence of alternative benefits of AMF from an increase in nutrient uptake. This will lead to a more holistic view of the mycorrhizal-plant association and a more accurate picture of the net impact on the plant or plant community in question.

Plants respond to stress by releasing biogenic volatile organic compounds (BVOCs). Green leaf volatiles (GLVs), which are abundantly produced across the plant kingdom, comprise an important group within the BVOCs. They can repel or attract herbivores and their natural enemies; and they can induce plant defences or prime plants for enhanced defence against herbivores and pathogens and can have direct toxic effects on bacteria and fungi. Unlike other volatiles, GLVs are released almost instantly upon mechanical damage and (a)biotic stress and could thus function as an immediate and informative signal for many organisms in the plant’s environment. We used a meta-analysis approach in which data from the literature on GLV production during biotic stress responses were compiled and interpreted.We identified that different types of attackers and feeding styles add a degree of complexity to the amount of emitted GLVs, compared with wounding alone. This meta-analysis illustrates that there is less variation in the GLV profile than we presumed, that pathogens induce more GLVs than insects and wounding, and that there are clear differences in GLV emission between monocots and dicots. Besides the meta-analysis, this review provides an update on recent insights into the perception and signalling of GLVs in plants.

The diversity of secondary compounds in the plant kingdom is huge. About 200,000 compounds are known, which are grouped into amines, non-protein amino acids, peptides, alkaloids, glucosinolates, cyanogenic glucosides, organic acids, terpenoids, quinones, polyacetylenes, and phenolics. The group of phenolic compounds consists of polyphenols, oligophenols and monophenols or simple phenolic compounds such as benzoic and cinnamic acids and their hydroxylated derivatives. Among the thousands of compounds present in ecological interactions, simple phenolic acids are the most abundant in soils, and many are described as allelochemicals. Given the physiological and biochemical importance of these compounds, we review their biosynthesis and metabolic actions in plants.

In this review, we describe the role of plant-derived biochemicals that are toxic to insect pests. Biotic stress in plants caused by insect pests is one of the most significant problems, leading to yield losses. Synthetic pesticides still play a significant role in crop protection. However, the environmental side effects and health issues caused by the overuse or inappropriate application of synthetic pesticides forced authorities to ban some problematic ones. Consequently, there is a strong necessity for novel and alternative insect pest control methods. An interesting source of ecological pesticides are biocidal compounds, naturally occurring in plants as allelochemicals (secondary metabolites), helping plants to resist, tolerate or compensate the stress caused by insect pests. The abovementioned bioactive natural products are the first line of defense in plants against insect herbivores. The large group of secondary plant metabolites, including alkaloids, saponins, phenols and terpenes, are the most promising compounds in the management of insect pests. Secondary metabolites offer sustainable pest control, therefore we can conclude that certain plant species provide numerous promising possibilities for discovering novel and ecologically friendly methods for the control of numerous insect pests.

Allelopathy is a process by which a plant releases chemicals that inhibit competitors. Recent phytochemical studies have reported the presence of phenolic molecules in some species of Pilosocereus, which could be indicative of allelopathic effect. The aim of this study was to assess the allelopathic potential of the fruit pulp extract of Pilosocereus gounellei on the germination of seeds of Lactuca sativa and P. gounellei. We tested the effects of pulp extract at four different concentrations. We measured the osmotic potential of the extract at the different concentrations, in order to assess its effect on seed germination. The extract negatively affected the germination parameters of both species and effect was more significant at higher extract concentrations. The influence of the osmotic potential on the germination parameters was not significant for most of the studied parameters. We believe that our results are indicative that the fruit pulp extract of P. gounellei contains allelochemicals that delayed or inhibited seed germination of not only L. sativa, but also of seeds of their own species (autoallelopathy). Further studies are necessary to clarify the inhibition mechanisms, and how widespread the allelopathy is across other cactus species.