Explore the vast range of titles available.

Background Microbes isolated from hyperaccumulating plants have been reported to be effective in achieving higher phytoextraction efficiency. The plant growth-promoting bacteria (PGPB) SaMR12 from the cadmium (Cd)/zinc hyperaccumulator Sedum alfredii Hance could promote the growth of a non-host plant, oilseed rape, under Cd stress. However, the effect of SaMR12 on Brasscia juncea antioxidative response under Cd exposure was still unclear. Results A hydroponic experiment was conducted to study the effects of Sphingomonas SaMR12 on its non-host plant Brassica juncea (L.) Czern. under four different Cd treatments. The results showed that SaMR12 could colonize and aggregate in the roots and then move to the shoots. SaMR12 inoculation promoted plant growth by up to 71% in aboveground biomass and 81% in root biomass over that of the non-inoculated plants. SaMR12-inoculated plants significantly enhanced root Cd accumulation in the 10 and 20 μM Cd treatments, with 1.72- and 0.86-fold increases, respectively, over that of the non-inoculated plants. SaMR12 inoculation not only decreased shoot hydrogen peroxide (H 2 O 2 ) content by up to 38% and malondialdehyde (MDA) content by up to 60% but also reduced proline content by 7–30% in shoots and 17–32% in roots compared to the levels in non-inoculated plants. Additionally, SaMR12 inoculation promoted the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) and facilitated the relative gene expression levels of dehydroascorbate reductase ( DHAR ) and glutathione reductase ( GR ) involved in the glutathione (GSH)-ascorbic acid (AsA) cycle. Conclusions The results demonstrated that, under Cd stress, SaMR12 inoculation could activate the antioxidative response of B. juncea by decreasing the concentrations of H 2 O 2 , MDA and proline, increasing the activities of antioxidative enzymes, and regulating the GSH-AsA cycle. These results provide a theoretical foundation for the potential application of hyperaccumulator endophytic bacteria as remediating agents to improve heavy metal tolerance within non-host plant species, which could further improve phytoextraction efficiency. Graphical abstract

In the Tibetan Plateau grassland ecosystems, nitrogen (N) availability is rising dramatically; however, the influence of higher N on the arbuscular mycorrhizal fungi (AMF) might impact on plant competitive interactions. Therefore, understanding the part played by AMF in the competition between Vicia faba and Brassica napus and its dependence on the N-addition status is necessary. To address this, a glasshouse experiment was conducted to examine whether the grassland AMF community’s inocula (AMF and NAMF) and N-addition levels (N-0 and N-15) alter plant competition between V. faba and B. napus . Two harvests took day 45 (1 st harvest) and day 90 (2 nd harvest), respectively. The findings showed that compared to B. napus , AMF inoculation significantly improved the competitive potential of the V. faba . In the occurrence of AMF, V. faba was the strongest competitor being facilitated by B. napus in both harvests. While under N-15, AMF significantly enhanced tissue N:P ratio in B. napus mixed-culture at 1 st harvest, the opposite trend was observed in 2 nd harvest. The mycorrhizal growth dependency slightly negatively affected mixed-culture compared to monoculture under both N-addition treatments. The aggressivity index of AMF plants was higher than NAMF plants with both N-addition and harvests. Our observation highlights that mycorrhizal associations might facilitate host plant species in mixed-culture with non-host plant species. Additionally, interacting with N-addition, AMF could impact the competitive ability of the host plant not only directly but also indirectly, thereby changing the growth and nutrient uptake of competing plant species.

Background Cuscuta japonica Choisy (Japanese dodder) is a parasitic weed that damages many plants and affects agricultural production. The haustorium of C. japonica plays a key role during parasitism in host plants; in contrast, some non-host plants effectively inhibit its formation. However, the metabolic differences between normal dodder in host plants and dodder inhibition in non-host plants are largely unknown. Here, we utilized an integrative analysis of transcriptomes and metabolomes to compare the differential regulatory mechanisms between C. japonica interacting with the host plant Ficus microcarpa and the non-host plant Mangifera indica . Results After parasitization for 24 h and 72 h, the differentially abundant metabolites between these two treatments were enriched in pathways associated with α-linolenic acid metabolism, linoleic acid metabolism, phenylpropanoid biosynthesis, and pyrimidine metabolism. At the transcriptome level, the flavor biosynthesis pathway was significantly enriched at 24 h, whereas the plant–pathogen interaction, arginine and proline metabolism, and MARK signaling-plant pathways were significantly enriched at 72 h, based on the differentially expressed genes between these two treatments. Subsequent temporal analyses identified multiple genes and metabolites that showed different trends in dodder interactions between the host and non-host plants. In particular, the phenylpropanoid biosynthesis pathway showed significant differential regulation between C. japonica in host and non-host plants. Conclusions These results provide insights into the metabolic mechanisms of dodder–host interactions, which will facilitate future plant protection from C. japonica parasitism.

Aims Arbuscular mycorrhizal (AM) symbioses affect plant competitive relationships within and among species and may be involved in the interactions among agricultural weed species and crops, depending on their mycorrhizal status. In this work, the impact of native AM fungi (AMF) on maize-weed(s) and weed—weed competitive relationships was assessed, using Solanum nigrum and Chenopodium album as model host and non-host weeds, respectively. Methods Growth performance, nutrient use and competitive ability of crop and weed species were assessed in the pure stand and in different model plant communities of host and non-host species. Results Results showed that maize performance decrease was more severe when grown with C. album than with S. nigrum. Differential responses to AMF occurred in the two weed species tested: mycorrhizal S. nigrum showed reduced biomass and N uptake when grown in competition with C. album. The negative performances observed when mycorrhizal S. nigrum grew in competition with C. album corresponded to C. album larger biomass production and N uptake. Conclusions Results showed that AMF are able to alter the competitive relationships between co-occurring plant species differing in their mycorrhizal status (host/non-host), thus representing key soil organisms to be taken into account in sustainable weed management strategies.

A topic of confusion over the interactions between arbuscular mycorrhizal (AM) fungi and plants is the mycorrhizal status of some plant families such as Cyperaceae, which is generally considered to be non-mycorrhizal. Here, we conducted experiments to explore how the abiotic environmental conditions and AM network influence the interactions between AM fungi and Carex capillacea. We grew Carex capillacea alone or together with a mycorrhizal host species Medicago sativa in the presence or absence of AM fungi (soil inoculum from Mount Segrila and Rhizophagus intraradices from the Chinese Bank of the Glomeromycota, BGC). Plants were grown in a growth chamber and at two elevational sites of Mount Segrila, respectively. The results indicate that mycorrhizal host plants ensured the presence of an active AM fungal network whether under growth chamber or alpine conditions. The AM fungal network significantly depressed the growth of C. capillacea, especially when native inocula were used and the plants grew under alpine site conditions, although root colonization of C. capillacea increased in most cases. Moreover, the colonization level of C. capillacea was much higher (≤ 30%) when growing under alpine conditions compared with growth chamber conditions (< 8.5%). Up to 20% root colonization by Rhizophagus intraradices was observed in monocultures under alpine conditions. A significant negative relationship was found between shoot phosphorus concentrations in M. sativa and shoot dry mass of C. capillacea. These results indicate that growing conditions, AM network, and inoculum source are all important factors affecting the susceptibility of C. capillacea to AM fungi, and growing conditions might be a key driver of the interactions between AM fungi and C. capillacea.

Lupinus species have been sporadically reported to be colonized by arbuscular mycorrhizal fungi (AMF). The interactions between AMF and lupine plants could also be non-symbiotic, from positive to negative, as controlled by the stress conditions of the plant. The goal of the study was to reveal the existence of such positive interactions and provide preliminary data for a myco-phytoremediation technology of mining dumps using L. angustifolius as a first crop. The objective was to test the hypothesis that the AMF inoculation of an acidified dump material contaminated with heavy metals would improve the growth of L. angustifolius and decrease oxidative stress. The design consisted of a one-month bivariate pot experiment with plants grown in a mining dump soil inoculated and not inoculated with a commercial AMF inoculum sequestered in expanded clay and watered with acidic and neutral water. There was no AMF root colonization under the experimental conditions, but under neutral and acidic water conditions, the phosphorus concentrations in roots and leaves increased, and the superoxide dismutase and peroxidase activities significantly decreased due to AMF inoculation. The increase in leaf phosphorus concentration was correlated with the decrease in peroxidase activity. The fresh weight of shoots and leaves significantly increased due to the commercial inoculum (under acidic water conditions). At the end of the experiment, the ammonium concentration in the substrate was higher in the inoculated treatments than in the not inoculated ones, and the concentrations of many elements in the dump material decreased compared to the start of the experiment. A comprehensive discussion of the potential mechanisms underlying the effects of the commercial AMF inoculum on the non-host L. angustifolius is completed.

The castor bean, Ricinus communis L., is a non-host plant for the large black chafer, Holotrichia parallela Motschulsky (Coleoptera: Scarabaeidae). In laboratory bioassays we found that this plant was no less attractive than the main host plant (peanut, Arachis hypogaea) and three food plant species: velvetleaf (Abutilon theophrasti), the glossy privet (Ligustrum lucidum), and the Siberian elm (Ulmus pumila). In field trapping experiments a Soxhlet extract of castor bean leaves caught more beetles than the optimal sex lure blend [(R)-(−)-linalool and (L)-isoleucine methyl ester blended in a ratio of 1:4], compared at equal doses (500 μl), and laboratory bioassays indicated that a castor bean plant could enhance the attractiveness of different blend ratios of sex lures. Olfactometer bioassays showed that males prefer volatiles emitted from different combinations of castor bean plant extracts and a signaling female over a female alone. In the presence of castor bean plants copulation rates of H. parallela were highest among all test environments both in laboratory bioassays (60%) and in field tests (70%). This study, combined with our previous observation of the feeding behavior of H. parallela adults on castor bean leaves, suggests that castor bean plants may provide an attractive but risky mating site for H. parallela beetles. The enhancement of male mate-location and copulation rate in the presence of castor bean plants can balance its paralytic effects on H. parallela after intake of potential toxins contained in its leaves.

In order to locate mates, food, and oviposition sites, insects mainly rely on volatile cues released by their sexual partners, food sources, and host and non-host plants. Calling, mating, and oviposition behaviors, as well as fecundity and longevity, of newly emerged Spodoptera littoralis (Bois.) moths were recorded in the presence of volatiles from leaves of a host plant, Gossypium hirsutum (cotton) and two non-host plants, Adhatoda vasica ( Av ) or Picea abies (spruce), either alone or in host/non-host combinations. Females exposed to cotton volatiles started calling earlier than females exposed to non-host plant volatiles (NHV), or the blank control. Likewise, moth pairs exposed to cotton volatiles started mating earlier than the other treatments. The period of calling in females alone was longer than females kept with males, having the opportunity to mate. However, the callings, as well as mating durations in the moth pairs, in different treatments were not different. Longevity was decreased either in the absence of cotton or the presence of Av , and spruce leaves. Fecundity was reduced in moths exposed to a combination of spruce and cotton. The effect of NHV on attraction of 2-3–day-old male moths towards a pheromone (Ph) source was studied in a wind tunnel. In the no-choice assay, more males arrived at close approach and landed on the Ph source when the host plant, cotton, was offered in the background as compared to the non-hosts. In the dual-choice assay, more males landed on the Ph source in front of the host plant compared to the Ph source in front of non-hosts. Gas chromatography-electroantennographic detection on female S. littoralis revealed five antennally active compounds in headspace collections of spruce and three compounds in Av .

In phytophagous insects, experience can increase positive responses towards non-host plant extracts or induce oviposition on non-host plants, but the underlying chemical and behavioral mechanisms are poorly understood. By using the diamondback moth, Plutella xylostella, its host plant Chinese cabbage, and a non-host plant Chrysanthemum morifolium, as a model system, we observed the experience-altered olfactory responses of ovipositing females towards volatiles of the non-host plant, volatiles of pure chemicals (p-cymene and α-terpinene) found in the non-host plant, and volatiles of host plants treated with these chemicals. We assessed the experience-altered oviposition preference towards host plants treated with p-cymene. Naive females showed aversion to the odors of the non-host plant, the pure chemicals, and the pure chemical-treated host plants. In contrast, experienced females either became attracted by these non-host odors or were no longer repelled by these odors. Similarly, naive females laid a significantly lower proportion of eggs on pure chemical-treated host plants than on untreated host plants, but experienced females laid a similar or higher proportion of eggs on pure chemical-treated host plants compared to untreated host plants. Chemical analysis indicated that application of the non-host pure chemicals on Chinese cabbage induced emissions of volatiles by this host plant. We conclude that induced preference for previously repellent compounds is a major mechanism that leads to behavioral changes of this moth towards non-host plants or their extracts.

Fruit flies have evolved mechanisms using olfactory and visual signals to find and recognize suitable host plants. The objective of the present study was to determine how habitat patterns may assist fruit flies in locating host plants and fruit. The tomato fruit fly, Neoceratitis cyanescens (Bezzi), was chosen as an example of a specialized fruit fly, attacking plants of the Solanaceae family. A series of experiments was conducted in an outdoor field cage wherein flies were released and captured on sticky orange and yellow spheres displayed in pairs within or above potted host or non-host plants. Bright orange spheres mimicking host fruit were significantly more attractive than yellow spheres only when placed within the canopy of host plants and not when either within non-host plants or above both types of plants. Additional experiments combining sets of host and non-host plants in the same cage, or spraying leaf extract of host plant (bug weed) on non-host plants showed that volatile cues emitted by the foliage of host plants may influence the visual response of flies in attracting mature females engaged in a searching behaviour for a laying site and in assisting them to find the host fruit. Moreover, the response was specific to mature females with a high oviposition drive because starved mature females, immature females and males showed no significant preference for orange spheres. Olfactory signals emitted by the host foliage could be an indicator of an appropriate habitat, leading flies to engage in searching for a visual image.