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Plant-associated microorganisms can negatively influence plant growth, which makes them potential biocontrol agents for weeds. Two Gammaproteobacteria, Serratia plymuthica and Pseudomonas brassicacearum, isolated from roots of Jacobaea vulgaris, an invasive weed, negatively affect its root growth. We examined whether the effects of S. plymuthica and P. brassicacearum on J. vulgaris through root inoculation are concentration-dependent and investigated if these effects were mediated by metabolites in bacterial suspensions. We also tested whether the two bacteria negatively affected seed germination and seedling growth through volatile emissions. Lastly, we investigated the host specificity of these two bacteria on nine other plant species. Both bacteria significantly reduced J. vulgaris root growth after root inoculation, with S. plymuthica showing a concentration-dependent pattern in vitro. The cell-free supernatants of both bacteria did not affect J. vulgaris root growth. Both bacteria inhibited J. vulgaris seed germination and seedling growth via volatiles, displaying distinct volatile profiles. However, these negative effects were not specific to J. vulgaris. Both bacteria negatively affect J. vulgaris through root inoculation via the activity of bacterial cells, while also producing volatiles that hinder J. vulgaris germination and seedling growth. However, their negative effects extend to other plant species, limiting their potential for weed control., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Background: Microstegium vimineum (Trin.) A. Camus, commonly called stiltgrass, is a dominant weed in the United States and China. Although a lot of control approaches have been attempted, an economic, effective and practical measure has not been available to control the weed so far., Results: A serious rust disease of Microstegium vimineum was observed in three regions of Wenzhou city in China, from 2019 to 2021, with a disease incidence ranging from 82% to 97%. Typical rust disease symptoms on Microstegium vimineum were prominently visible during the early monsoon season (June-July), with chlorotic spots on the leaf surfaces. The morphological characterization of the strain WZ-1 which was isolated from the diseased leaves was consistent with Puccinia polliniicola. The virulence tests showed that the average disease index of Microstegium vimineum plants could reach 35% at 10 days post-inoculation. The host specificity of Puccinia polliniicola was tested on 64 plant species from 12 families and it did not cause any diseased symptoms on 24 major crops and 36 weeds, but slightly infected four gramineous weeds, Arthraxon hispidus, Polypogon fugax, Cynodon dactylon, and Microstegium ciliatum. However, newly-produced urediniospores were not observed on the slightly infected plants. The urediniospores of strain WZ-1 infected the Microstegium vimineum leaves by two main approaches: mycelium or appressorium invaded the stoma; and mycelium or appressorium directly invaded intercellular spaces. Field experiments showed that the rust disease naturally prevailed among Microstegium vimineum populations, causing severe rust disease symptoms on the leaf surface. The rust epidemic effectively controlled all of the target plants in the closed plot where the rust was released., Conclusion: Puccinia polliniicola strain WZ-1 has great potential to be used as a classical biological control agent against Microstegium vimineum. © 2024 Society of Chemical Industry., (© 2024 Society of Chemical Industry.)

Cover crops and flower strips are used in agricultural fields as part of integrated pest management strategies. However, their potential as secondary hosts of soilborne pathogens such as Sclerotinia sclerotiorum in oilseed rape cultivation is not fully comprehended. In the current study, we evaluated the effect of pathogen virulence on the development of Sclerotinia stem/leaf rot and sclerotia production in 33 plant species from 11 botanical families using two S. sclerotiorum isolates. Furthermore, the effect of sclerotial size on carpogenic germination was studied. Results showed that the pathogen's virulence significantly affected the occurrence and development of Sclerotinia stem/leaf rot and the subsequent production of sclerotia. Among all plant species tested, 26 were more susceptible to the highly aggressive S . sclerotiorum isolate, which produced more and bigger sclerotia in 17 species than the less aggressive isolate. Moreover, a stronger positive correlation was found between the relative lesion length of plants inoculated with the highly aggressive isolate and the number of sclerotia produced by this isolate (Spearman's rank correlation coefficient [ r s ] = 0.572; P = 0.004). Additionally, we found that larger and heavier sclerotia produced stipes and apothecia earlier and at a greater rate than smaller ones. The heavyweight class had the highest carpogenic germination rate (82.4%), followed by the average (67.2%) and lightweight classes (59.5%). Our findings highlight the need for further investigation into the potential risks associated with cover crops, weeds, and flower strips as secondary hosts of soilborne pathogens in agricultural fields., Competing Interests: The author(s) declare no conflict of interest.

Endophytic bacteria, recognized as eco-friendly biofertilizers, have demonstrated the potential to enhance crop growth and yield. While the plant growth-promoting effects of endophytic bacteria have been extensively studied, the impact of weed endophytes remains less explored. In this study, we aimed to isolate endophytic bacteria from native weeds and assess their plant growth-promoting abilities in rice under varying chemical fertilization. The evaluation encompassed measurements of mineral phosphate and potash solubilization, as well as indole-3-acetic acid (IAA) production activity by the selected isolates. Two promising strains, tentatively identified as Alcaligenes faecalis (BTCP01) from Eleusine indica (Goose grass) and Metabacillus indicus (BTDR03) from Cynodon dactylon (Bermuda grass) based on 16S rRNA gene phylogeny, exhibited noteworthy phosphate and potassium solubilization activity, respectively. BTCP01 demonstrated superior phosphate solubilizing activity, while BTDR03 exhibited the highest potassium (K) solubilizing activity. Both isolates synthesized IAA in the presence of L-tryptophan, with the detection of nifH and ipdC genes in their genomes. Application of isolates BTCP01 and BTDR03 through root dipping and spraying at the flowering stage significantly enhanced the agronomic performance of rice variety CV. BRRI dhan29. Notably, combining both strains with 50% of recommended N, P, and K fertilizer doses led to a substantial increase in rice grain yields compared to control plants receiving 100% of recommended doses. Taken together, our results indicate that weed endophytic bacterial strains BTCP01 and BTDR03 hold promise as biofertilizers, potentially reducing the dependency on chemical fertilizers by up to 50%, thereby fostering sustainable rice production., Competing Interests: The authors declare no competing interests., (Copyright: © 2024 Fatema et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Weedy rice is a major problem in paddy fields around the world. It is well known that weedy rice appears to grow faster and mature earlier than cultivated rice. It is possible that differences in the root microbial genetics are correlated with this characteristic. This study incorporated 16S rRNA amplicon sequencing to study the microbial composition in the rhizosphere and endosphere of rice root. No significant difference was found between the microbiota associated with weedy and cultivated rice lines grown in the same field. It was found that the endosphere had less microbial diversity compared to the rhizosphere. The major groups of bacteria found in the endosphere are from the phylum Proteobacteria, Myxococcota, Chloroflexota, and Actinobacteria. In addition, by analyzing the microbiome of japonica rice grown in the field in a temperate climate, we found that despite differences in genotype and location, some bacterial taxa were found to be common and these members of the putative rice core microbiome can also be detected by in situ hybridization. The delineation of a core microbiome in the endosphere of rice suggests that these bacterial taxa might be important in the life cycle of a wide range of rice types., (© 2024. The Author(s).)

Mango malformation disease (MMD) caused by Fusarium spp. is an important limiting factor in most production areas worldwide. Fusarium mexicanum and F. pseudocircinatum have been reported as causing MMD in Mexico. These two pathogens also cause a similar disease in Swietenia macrophylla (big-leaf mahogany malformation disease) in central western Mexico, and F. pseudocircinatum was recently reported as causing malformation disease in Tabebuia rosea (rosy trumpet) in the same region. These studies suggest that additional plant species, including weeds, might be hosts of these pathogens. The role that weed hosts might have in the disease cycle is unknown. The objectives of this work were to recover Fusarium isolates from understory vegetation in mango orchards with MMD, identify the Fusarium isolates through DNA sequence data, and determine whether F. mexicanum is capable of inducing disease in the weedy legume Senna uniflora (oneleaf senna). Additional objectives in this work were to compare Fusarium isolates recovered from weeds and mango trees in the same orchards by characterizing their phylogenetic relationships, assessing in vitro production of mycotoxins, and identifying their mating type idiomorph. A total of 59 Fusarium isolates from five species complexes were recovered from apical and lateral buds from four weed species. Two of the species within the F. fujikuroi species complex are known to cause MMD in Mexico. Trichothecene production was detected in five isolates, including F. sulawense and F. irregulare in the F. incarnatum-equiseti species complex and F. boothii in the F. sambucinum species complex. Both mating types were present among mango and weed isolates. This is the first report of herbaceous hosts harboring Fusarium species that cause mango malformation in Mexico. The information provided should prove valuable for further study of the epidemiological role of weeds in MMD and help manage the disease.

Cruciferous weeds have been shown to harbor diverse Xanthomonas campestris pathovars, including the agronomically damaging black rot of cabbage pathogen, X. campestris pv. campestris. However, the importance of weeds as inoculum sources for X. campestris pv. campestris outbreaks in New York remains unknown. To determine if cruciferous weeds act as primary reservoirs for X. campestris pv. campestris , fields that were rotating between cabbage or had severe black rot outbreaks were chosen for evaluation. Over a consecutive 3-year period, 148 cruciferous and noncruciferous weed samples were collected at 34 unique sites located across five New York counties. Of the 148 weed samples analyzed, 48 X. campestris isolates were identified, with a subset characterized using multilocus sequence analysis. All X. campestris isolates originated from weeds belonging to the Brassicaceae family, with predominant weed hosts being shepherd's purse ( Capsella bursa-pastoris ), wild mustard ( Sinapis arvensis ), yellow rocket ( Barbarea vulgaris ), and pennycress ( Thlaspi arvense ). Identifying pathogenic X. campestris weed isolates was rare, with only eight isolates causing brown necrotic leaf spots or typical V-shaped lesions on cabbage. There was no evidence of cabbage-infecting weed isolates persisting in an infected field by overwintering in weed hosts; however, similar cabbage and weed X. campestris haplotypes were identified in the same field during an active black rot outbreak. X. campestris weed isolates are genetically diverse both within and between fields, but our findings indicate that X. campestris weed isolates do not appear to act as primary sources of inoculum for B. oleracea fields in New York.

Crop yield and quality are affected by the presence of weeds such as Palmer amaranth. Chemical control is the most commonly used method to eradicate weeds, due to its quickness and efficacy. However, the inappropriate use of chemical herbicides can lead to resistant weed biotypes, as well as problems related to environmental pollution and human health hazards. One ecological alternative to combat weeds is the use of deleterious rhizobacteria (DRB). We evaluated the potential bioherbicidal effect in 15 DRB isolates from the rhizosphere of Palmer amaranth, both in vitro and in greenhouse tests. Isolates TR10 and TR18 inhibited seed germination in vitro, whereas the TR25 and TR36 isolates showed the potential to inhibit Palmer amaranth plant development in growth room assays without affecting maize and common bean germination and growth. These four isolates were molecularly identified as either Pseudomonas sp. (TR10 and TR36), Enterobacter sp. (TR18), or Bacillus sp. (TR25). In addition, the production of volatiles and diffusible metabolites were identified as possible mechanisms of germination arrestment and plant development inhibition. This study suggests the bioherbicide potential of some indigenous rhizobacteria against Palmer amaranth., (© 2021. Sociedade Brasileira de Microbiologia.)

Weed, an abundant biomass, is considered unsuitable as a raw material for methane production. There are few reports on the anaerobic digestion of weeds without the addition of other organic wastes. To solve this problem, a methane-producing microbial community with weed as a sole feedstock was established. This study mainly focused on the degree of contribution between water-soluble and -insoluble fractions of the weed to methane production; thus, methane production from both fractions was tested separately. Methane production after 80-day batch cultures with whole weed, water-soluble and water-insoluble fractions was 184.5, 96.8 and 26.5 NmL g-1 dry matter (DM), respectively. The results of 16S rRNA gene amplicon sequence analysis revealed that Proteiniphilum saccharofermentans and several Methanobacterium species commonly dominated all cultures, whereas the population dynamics of minor species differed in every culture. Moreover, the remixed culture of microbial communities adapted to water-soluble and -insoluble fractions recovered methane production (252.4 NmL g-1 DM). Based on these results, it can be strongly inferred that colocalizing the minor species in water-soluble and -insoluble fractions is important for effective methane production., (© The Author(s) 2021. Published by Oxford University Press on behalf of FEMS.)

To determine if Ageratina adenophora can accumulate diverse pathogens from surrounding native plants, we intensively sampled fungal communities, including endophytes, leaf spot pathogens and canopy air fungi, associated with Ag. adenophora as well as native plants in its invasive range. In total, we collected 4542 foliar fungal strains from 10 geographic sites, including 1340 from healthy leaves of Ag. adenophora , 2051 from leaf spots of Ag. adenophora and 1151 from leaf spots of 56 species of native plants and crops. Taxonomically, the common fungal genera included Colletotrichum , Diaporthe , Alternaria , Nemania , Xylaria , Neofusicoccum , Nigrospora , Epicoccum , Gibberella , Pestalotiopsis , Irpex , Schizophyllum and Clonostachys . We also isolated the cultivable fungi from 12 air samples collected from six areas in Yunnan Province, PR China. Among the total of 1255 air fungal isolates, the most common genera were Cladosporium , Trichoderma and Epicoccum . Among them, two new Remotididymella species, Remotididymella ageratinae from leaf spot of Ag. adenophora and Remotididymella anemophila from canopy air of Ag. adenophora were found. The two species showed both asexual and sexual reproductive structures. The conidia of R. ageratinae and R. anemophila are larger than those of R. anthropophila and R. destructiva . The size of ascospores of R. ageratinae and R. anemophila also differ from R. bauhiniae . Phylogenetic analysis of the combined ITS, LSU rRNA, rpb2 and tub2 sequences showed that R. ageratinae and R. anemophila each formed a distinct clade, separated from all species previously described in Remotididymella and confirmed them as new species belonging to Remotididymella . Full descriptions of R. ageratinae and R. anemophila are provided in this study.

To examine the genetic basis for the variable susceptibility of Striga hermonthica from differing zones of sub-Saharan Africa to Fusarium oxysporum f. sp. strigae (Fos) isolates Foxy-2 and FK3, 10 S. hermonthica populations from Eastern and Western Africa were phenotyped for their susceptibility response to Foxy-2 and FK3, and then genotyped with 22 simple sequence repeat (SSR) markers. There is low genetic differentiation between East African and West African S. hermonthica populations (i.e. the proportion of the total genetic variance contained in the subpopulation relative to the total genetic variance, F ST  = 0.012, P < 0.05), but intermediate genetic differentiation (F ST  = 0.143, P < 0.01) underlies the S. hermonthica groups that are differentiated by their phenotypic responses to Fos isolates. An expressed sequence tag SSR (EST-SSR) marker Y53 (P < 0.01) and a genomic SSR marker E1009 (P < 0.05) were associated with the S. hermonthica class susceptible to Foxy-2 and FK3 (group A). A divergent S. hermonthica class, consisting of groups with intermediate susceptibility to Foxy-2 (group B) and susceptibility to either FK3 (group C) or Foxy-2 (group D), showed no marker-trait association, instead demonstrated linkage disequilibrium decay. Owing to point substitutions and insertion-deletion mutations, the unique, protein-coding nucleotide sequence at the E1009 locus in group A was partly dissimilar to group B, but was totally distinct from groups C and D. These findings implied that the inconsistent effectiveness of a Fos isolate is better explained by genomic variation in S. hermonthica, rather than by S. hermonthica sampling zones., (© 2020 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.)

Impatiens glandulifera or Himalayan balsam (HB), is an invasive alien weed throughout the British Isles (BI). Classical biological control of HB in the BI using a rust fungus from the Himalayan native range was implemented in 2014. However, not all HB populations are susceptible to the two rust strains currently released. Additional strains are needed that infect resistant populations in order to achieve successful control. These are best sourced from the historical collecting sites. A molecular analysis was conducted using six chloroplast DNA sequences from leaf material from across the BI and the native range. Herbarium samples collected in the Himalayas between 1881 and 1956 were also included. Phylogenetic analyses resulted in the separation of two distinct groups, one containing samples from the BI and the native range, and the other from the BI only; suggesting that HB was introduced into the BI on at least two occasions. The former group is composed of two subgroups, indicating a third introduction. Ten and 15 haplotypes were found in the introduced and native range respectively, and with two of these found in both regions. Results show where to focus future surveys in the native range to find more compatible rust strains.

Phelipanche Aegyptiaca: is an obligate holo-parasitic weedlacking a functional photosynthetic system, which subsists on roots of a wide range of host crops, causing severe losses in yield quality and quantity. The parasite and its host are connected through their vascular system, forming a unique ecological system that enables the exchange of various substances. In a previous study, it was suggested that endophytic bacteria, which naturally inhabit the internal tissues of plants, can also be transmitted from the parasitic weed to its host and vice versa . In the current study, we investigate the characteristics of a previously isolated Pseudomonas sp. PhelS10 strain using both biochemical and molecular methods. This isolate was obtained from tomato plant tissue and was able to reduce P. aegyptiaca parasitism, and thus it may serve as a biocontrol agent. Our results revealed that production of Pseudomonas aeruginosa quinolone signal (PQS) was 2.1 times higher than that of the standard Pseudomonas aeruginosa strain (PAO1), which contributed to a 22% higher biofilm formation capability. PhelS10 strain was detected in the xylem of tomato plants using FISH analysis. In addition, PhelS10 strain was found in the parasitic weed's inner tissues, confirming the hypothesis that endophytic bacteria traffic between the host plant and its parasitic weed.

Symptoms of phytoplasma infection were observed in different weed species, Bidens subalternans , Conyza bonariensis , Heterosperma ovatifolium and Conium maculatum , collected from diverse geographical regions in Argentina. To confirm the association of phytoplasma infection with symptomatic plants, PCR, RFLP and phylogenetic analyses based on 16S rRNA-encoding sequences were performed. In this work, we report the presence of phytoplasmas from group 16SrVII (subgroup 16VII-B) infecting C. bonariensis and B. subalternans and from group 16SrIII (subgroup 16SrIII-X) B. subalternans , H. ovatifolium , and C. maculatum . Phytoplasmas from the aster yellows group were detected infecting C. bonariensis and B. subalternans . Analysis of 16S rRNA-encoding genes revealed the presence of two distinct operons, rrnB (16SrI-B) and newly described rrnA , which is different from the reference RFLP patterns of all previously established 16SrI-subgroups. A single rp operon sequence analysis reveals the presence of simple infection and confirms a description of a novel subgroup. On the basis of these results we propose a designation of new subgroup 16SrI-(B/AJ) AJ ( rp -AJ). To our knowledge, this is the first report of phytoplasmas infecting Bidens subalternans ¸ Heterosperma ovatifolium and Conium maculatum .

Rosellinia necatrix causes white root rot in various plants, including the Japanese pear. PCR assays using specific primers for R. necatrix detected the fungus on the roots of nine weed species from infested pear orchards. The soil inoculation experiment revealed that the spread of R. necatrix was similar between weed-mowed and non-weed-mowed treatments under field conditions. The spread of R. necatrix was also observed when rescue grass (Bromus catharticus) was grown in planter boxes under greenhouse conditions, but was limited without the grass, suggesting that some weeds facilitate the spread of R. necatrix in soil.

Microbiomes can significantly expand the genomic potential of plants, contributing to nutrient acquisition, plant growth promotion and tolerance to (a)biotic stresses. Among biotic stressors, root parasitic weeds (RPWs), mainly of the genera Orobanche, Phelipanche and Striga, are major yield-limiting factors of a wide range of staple crops, particularly in developing countries. Here, we provide a conceptual synthesis of putative mechanisms by which soil and plant microbiomes could be harnessed to control RPWs. These mechanisms are partitioned in direct and indirect modes of action and discussed in the context of past and present studies on microbe-mediated suppression of RPWs. Specific emphasis is given to the large but yet unexplored potential of root-associated microorganisms to interfere with the chemical signalling cascade between the host plant and the RPWs. We further provide concepts and ideas for future research directions and prospective designs of novel control strategies., (Copyright © 2019 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The present study is the first report of utilizing Tithonia rotundifolia weed as a substrate for inulinase production from Fusarium solani JALPK. It also deals with the statistical optimization of culture conditions to enhance the enzyme yield. Amongst the 11 variables screened by Plackett- Burman design, Inulin in combination with Agave sisalana extract, Tithonia rotundifolia extract and NaNO 3 had a significant influence on inulinase production and their concentrations were further optimized employing Box Behnken design. An enhancement of inulinase production from 970 EU/mL to 3261.011 EU/mL was gained after media optimization. Amongst the screened carbon sources Tithonia rotundifolia was found to be very effective in stimulating elevated inulinase synthesis. The Tithonia rotundifolia weed extract was treated with inulinase from Fusarium solani JALPK to form fructose which was estimated spectrophotometrically. This liberated fructose was also confirmed by osazone formation test and FTIR. HPTLC analysis of product revealed the exoinulinase nature of the enzyme produced by Fusarium solani JALPK since fructose was the only end product after hydrolysis of inulin rich weed in fermented broth. Thus the elevated extracellular inulinase yielding novel property of Fusarium solani JALPK (KY914560) contributes in considering it as a potential candidate with food, pharmaceutical and bioremediation applications., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Microbotryum silybum , a smut fungus, is studied as an agent for the biological control of Silybum marianum (milk thistle) weed. Confirmation of the systemic infection is essential in order to assess the effectiveness of the biological control application and assist decision-making. Nonetheless, in situ diagnosis is challenging. The presently demonstrated research illustrates the identification process of systemically infected S. marianum plants by means of field spectroscopy and the multilayer perceptron/automatic relevance determination (MLP-ARD) network. Leaf spectral signatures were obtained from both healthy and infected S. marianum plants using a portable visible and near-infrared spectrometer (310⁻1100 nm). The MLP-ARD algorithm was applied for the recognition of the infected S. marianum plants. Pre-processed spectral signatures served as input features. The spectra pre-processing consisted of normalization, and second derivative and principal component extraction. MLP-ARD reached a high overall accuracy (90.32%) in the identification process. The research results establish the capacity of MLP-ARD to precisely identify systemically infected S. marianum weeds during their vegetative growth stage.

In the present study, high throughput 16S rRNA gene sequencing was used to investigate soil invaded by the aggressive weed Ageratina adenophora to determine its effect on the species composition, distribution, and biodiversity of the bacterial communities. Soil samples from 12 micro-sites containing a monoculture of A. adenophora plants, mixtures of A. adenophora and different native plant species, and native species alone were studied. We found that the invasion of this weed resulted in a selection of bacteria belonging to phyla Acidobacteria and Verrucomicrobia and the lack of bacteria belonging to phyla Actinobacteria and Planctomycetes, but did not affect significantly the percentage abundances of members of other phyla. A similar bacterial population selection was also observed at genus or subgroup levels. The NO 3 - -N level was an important factor affecting soil bacterial communities and contributed to the dominance of A. adenophora. However, the numbers of total bacterial species, and the diversity and structure of soil bacterial microbiome did not (P > 0.05) change significantly following invasion by this weed.

Aims: To identify a potential pathogenic isolate of fungus on Convolvulus arvensis and to determine its phytotoxic activity, which revealed the presence of toxic metabolites responsible for the toxicity against the target weed., Methods and Results: A high virulent isolate of the fungus, Phoma crystallifera was isolated from symptomatic field bindweed in the west of Iran and was screened for the production of phytotoxins, which promoted necrosis on the detached leaves and seedlings of field bindweed in the bioassays. The isolate was distinct from other isolates of the fungi on the basis of morphological characteristics and the combined sequence database of the ITS region, partial LSU rDNA and β-tubulin gene. Isolate P. crystalifera P6 produced the highest amount of phytotoxins after 21 days in a shacked culture of Richard's broth. The active metabolites were isolated from a cell-free culture filtrate by ethyl-acetate and purified by thin layer chromatography. The result indicated that six out of nine spots had phytotoxic activity in the bioassays, with R f values of 0·16, 0·30, 0·36, 0·43, 0·57 and 0·81., Conclusions: Phoma crystallifera P6 and its active metabolites showed significant phytotoxic effects on the detached leaves of C. arvensis., Significance and Impact of the Study: To date, there are no reports of possible biocontrol agent(s) on C. arvensis in Iran. Thus, P. crystallifera P6 is introduced here as a severe pathogenic fungus and which can be used as a biocontrol agent against C. arvensis., (© 2017 The Society for Applied Microbiology.)

Weeds and crop plants select their microbiota from the same pool of soil microorganisms, however, the ecology of weed microbiomes is poorly understood. We analysed the microbiomes associated with roots and rhizospheres of grapevine and four weed species (Lamium amplexicaule L., Veronica arvensis L., Lepidium draba L. and Stellaria media L.) growing in proximity in the same vineyard using 16S rRNA gene sequencing. We also isolated and characterized 500 rhizobacteria and root endophytes from L. draba and grapevine. Microbiome data analysis revealed that all plants hosted significantly different microbiomes in the rhizosphere as well as in root compartment, however, differences were more pronounced in the root compartment. The shared microbiome of grapevine and the four weed species contained 145 OTUs (54.2%) in the rhizosphere, but only nine OTUs (13.2%) in the root compartment. Seven OTUs (12.3%) were shared in all plants and compartments. Approximately 56% of the major OTUs (>1%) showed more than 98% identity to bacteria isolated in this study. Moreover, weed-associated bacteria generally showed a higher species richness in the rhizosphere, whereas the root-associated bacteria were more diverse in the perennial plants grapevine and L. draba. Overall, weed isolates showed more plant growth-promoting characteristics compared with grapevine isolates., (© 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.)

Dynamics of the taxonomic structure of epiphytic bacterial communities of the rhizosphere and phyllosphere of seven weed species was studied. The major types of isolated organisms were identified using phenotypic and molecular biological approaches. Dispersion analysis revealed that the ontogenesis stage and plant organ were the factors with the greatest effect on the taxonomic structure of the communities. The dominant microorganisms of weeds were similar to those of cultivated plants. The minor components revealed in the spectra of bacterial communities of weeds belonged to poorly studied genera of chemolithotrophic proteobacteria.

Production of a bioherbicide for biological control of weeds requires a series of steps, from selection of a suitable microbial strain to final formulation. Thus, this study aimed to select fungi for production of secondary metabolites with herbicidal activity using biological resources of the Brazilian Pampa biome. Phytopathogenic fungi were isolated from infected tissues of weeds in the Pampa biome. A liquid synthetic culture medium was used for production of metabolites. The phytotoxicity of fungal metabolites was assessed via biological tests using the plant Cucumis sativus L., and the most promising strain was identified by molecular analysis. Thirty-nine fungi were isolated, and 28 presented some phytotoxic symptoms against the target plant. Fungus VP51 belonging to the genus Diaporthe showed the most pronounced herbicidal activity. The Brazilian Pampa biome is a potential resource for the development of new and sustainable chemical compounds for modern agriculture., (Copyright © 2016 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.)

Halotolerant bacteria associated with Psoralea corylifolia L., a luxuriantly growing annual weed in salinity-affected semi-arid regions of western Maharashtra, India were evaluated for their plant growth-promoting activity in wheat. A total of 79 bacteria associated with different parts viz., root, shoot and nodule endophytes, rhizosphere, rhizoplane, and leaf epiphytes, were isolated and grouped based on their habitat. Twelve bacteria isolated for their potential in plant growth promotion were further selected for in vitro studies. Molecular identification showed the presence of the genera Bacillus, Pantoea, Marinobacterium, Acinetobacter, Enterobacter, Pseudomonas, Rhizobium, and Sinorhizobium (LC027447-53; LC027455; LC027457, LC027459, and LC128410). The phylogenetic studies along with carbon source utilization profiles using the Biolog® indicated the presence of novel species and the in planta studies revealed promising results under salinity stress. Whereas the nodule endophytes had minute plant growth-promoting (PGP) activity, the cell free culture filtrates of these strains enhanced seed germination of wheat (Triticum aestivum L). The maximum vigor index was monitored in isolate Y7 (Enterobacter sp strain NIASMVII). Indole acetic acid (IAA) production by the isolates ranged between 0.22 and 25.58 μg mL -1 . This signifies the need of exploration of their individual metabolites for developing next-generation bio-inoculants through co-inoculation with other compatible microbes. This study has potential in utilization of the weed-associated microbiome in terms of alleviation of salinity stress in crop plants.

Purpose: To study ecology, morphology, ultrastructure and biochemical characteristics of phytopathogenic bacteria; to determine bacterial diseases of plants and the patterns of their occurrence and development of the infectious process, to develop the mechanisms for plant disease control., Methods: Microbiological, physiological, biochemical, statistical., Results: Bacterial diseases of agricultural crops and related weeds and their causative agents in different cropping systems were described. Ecological niches of plant pathogenic bacteria were determined. Specialization of agents of bacterial diseases in plants was identified., Conclusions: It was established that a wide deterioration of crops and related weeds is caused by pathogenic bacteria of the following genera: Pseudomonas, Xanthomonas, Pectobacterium, Clavibacter, and Curtobacterium.

Bacterial diseases, pests and weeds are the main factors that do not allow generating high yields of agricultural crops. The article presents the results of a study of agents of weed diseases. It was shown that the affected weeds in wheat agrophytocenosis present an ecological niche for phytopathogenic bacteria, belonging to the species Pseudomonas syringae, Pseudomonas viridiflava, Pseudomonas fluorescens, Pectobacterium carotovorum, Pantoea agglomerans, Xanthomonas translucens and Pseudomonas sp. In addition to these pathogens, phytopathogenic yeasts Rhodosporidium diobovatum and Rhodotorula sp. were isolated and identified. Most of the phytopathogens, isolated from weeds, are widely specialized and in experiment affect various species of weeds and cereals. Fatty acid composition of the total cellular lipids of these plant pathogens was identified and proved to be characteristic for each species of bacteria. P. syringae was determined as the main agent of bacterial diseases of weeds, its strains have a high degree of serological relationship to the agent of basal bacteriosis of cereals – P. syringae pv. atrofaciens and belong to the same serogroups. The results of RAPD-PCR analysis revealed that P. syringae strains isolated from weeds and disease agents of cereals present a genetically homogeneous group. The results obtained indicate that wheat and weeds are affected by the same agents of bacterial diseases.

Locoweed is a perennial herbaceous plant included in Astragalus spp. and Oxytropis spp. that contains the toxic indolizidine alkaloid swainsonine. The livestock that consume locoweed can suffer from a type of toxicity called locoism. There are aliphaticnitro compounds, selenium, selenium compounds, and alkaloids in locoweed. The toxic component in locoweed has been identified as swainsonine, an indolizidine alkaloid. Swainsonine inhibits lysosomal a-mannosidase and mannosidase II, resulting in altered oligosaccharide degradation and incomplete glycoprotein processing. Corresponding studies on endophytic fungi producing swainsonine have been isolated from a variety of locoweed, and these endophytic fungi and locoweed have a close relationship. Endophytic fungi can promote the growth of locoweed and increase swainsonine production. As a result, livestock that consume locoweed exhibit several symptoms, including dispirited behavior, staggering gait, chromatopsia, trembling, ataxia, and cellular vacuolar degeneration of most tissues by pathological observation. Locoism results in significant annual economic losses. Therefore, in this paper, we review the current research on locoweed, including that on locoweed species distribution in China, endophyte fungus in locoweed, the toxicology mechanism of locoweed, and the swainsonine effect on reproduction., (Copyright © 2016. Published by Elsevier B.V.)

Conyza canadensis is a noxious and notably problematic weed in Brazil whose control is greatly challenging due to the appearance, in the last years, of herbicide resistant populations. An investigation regarding the associated pathogenic fungi of this plant was conducted in Brazil aimed at starting a biological control program to help mitigate its economic impact. Ten fungal species were yielded and described: two ascomycetes (Leptosphaerulina conyzicola sp. nov. and Wentiomyces melioloides), five hyphomycete asexual morphs (Alternaria tenuissima, Cercospora conyzicola sp. nov., Cercosporella virgaureae, and Fusarium fujikuroi), two coelomycete asexual morphs (Phoma conyzaphthora sp. nov., Septoria erigerontis), one rust fungus (Aecidium conyzicola sp. nov.), and one oomycete (Basidiophora entospora). Four among the fungi that were collected represent new taxa, and the others represented either new host-records of known fungal species or new geographic records or both, except for C. virgaureae that had already been recorded on C. canadensis in Brazil. None of the discovered species have any potential to be used as a mycoherbicide or to be introduced somewhere else, nevertheless, the knowledge about this mycobiota will help guide the selection of potential biocontrol agents to be introduced in Brazil., (Copyright © 2016 British Mycological Society. Published by Elsevier Ltd. All rights reserved.)

Background: The outcome of the arms race between hosts and pathogens depends heavily on the interactions between their genetic diversity, population size and transmission ability. Theory predicts that genetically diverse hosts will select for higher virulence and more diverse pathogens than hosts with low genetic diversity. Cultivated hosts typically have lower genetic diversity and thus small effective population sizes, but can potentially harbour large pathogen population sizes. On the other hand, hosts, such as weeds, which are genetically more diverse and thus have larger effective population sizes, usually harbour smaller pathogen population sizes. Large pathogen population sizes may lead to more opportunities for mutation and hence more diverse pathogens. Here we test the predictions that pathogen neutral genetic diversity will increase with large pathogen population sizes and host diversity, whereas diversity under selection will increase with host diversity. We assessed and compared the diversity of a fungal pathogen, Rhynchosporium commune, on weedy barley grass (which have a large effective population size) and cultivated barley (low genetic diversity) using microsatellites, effector locus nip1 diversity and pathogen aggressiveness in order to assess the importance of weeds in the evolution of the neutral and selected diversity of pathogens., Results: The findings indicated that the large barley acreage and low host diversity maintains higher pathogen neutral genetic diversity and lower linkage disequilibrium, while the weed maintains more pathotypes and higher virulence diversity at nip1. Strong evidence for more pathogen migration from barley grass to barley suggests transmission of virulence from barley grass to barley is common., Conclusions: Pathogen census population size is a better predictor for neutral genetic diversity than host diversity. Despite maintaining a smaller pathogen census population size, barley grass acts as an important ancillary host to R. commune, harbouring highly virulent pathogen types capable of transmission to barley. Management of disease on crops must therefore include management of weedy ancillary hosts, which may harbour disproportionate supplies of virulent pathogen strains.

Unlabelled: Pseudomonas syringae pv. phaseolicola, the causative agent of halo blight in common bean (Phaseolus vulgaris L.), was isolated from weeds associated with bean crops in Spain. The bacterium was recovered from Fumaria sp, Mercurialis annua, Solanum nigrum and Sonchus oleraceus. Ps. s. pv. phaseolicola had previously been isolated from leguminous plants and S. nigrum, but to our knowledge, this is the first time it was recovered from the other three species. The isolates were phenotypically and genetically characterized, and they were compared with isolates recovered from common beans. Five different genotypic profiles were detected by PmeI-PFGE, two of them being of new description. Weed isolates were as pathogenic on bean plants as bean isolates, but they were not pathogenic on S. nigrum. Regarding the survival of the pathogen in weeds, Ps. s. pv. phaseolicola was isolated from So. oleraceus 11 weeks after the end of the bean crop. These results strongly support the idea of weeds as a potential source of inoculum for halo blight in bean., Significance and Impact of the Study: It has traditionally been considered that the main source of inoculum of Pseudomonas syringae pv. phaseolicola causing halo blight disease in Phaseolus vulgaris are the bean seeds, and that the host range of the bacterium is almost restricted to leguminous plants. In this study, the bacterium was recovered from four nonleguminous weed species collected in bean fields, and its permanence in weeds for at least 11 weeks after the harvesting of the beans was demonstrated. We have also proved that the strains isolated from weeds were pathogenic on bean plants. Accordingly, the host range of Ps. s. pv. phaseolicola could be broader than previously thought and weeds appear to be acting as a reservoir of the pathogen until the next crop., (© 2016 The Society for Applied Microbiology.)

Herbicide tolerance in crops and weeds is considered to be monotrophic, i.e. determined by the relative susceptibility of the physiological process targeted and the plant's ability to metabolise and detoxify the agrochemical. A growing body of evidence now suggests that endophytes, microbes that inhabit plant tissues and provide a range of growth, health and defence enhancements, can contribute to other types of abiotic and biotic stress tolerance. The current evidence for herbicide tolerance being bitrophic, with both free-living and plant-associated endophytes contributing to tolerance in the host plant, has been reviewed. We propose that endophytes can directly contribute to herbicide detoxification through their ability to metabolise xenobiotics. In addition, we explore the paradigm that microbes can 'prime' resistance mechanisms in plants such that they enhance herbicide tolerance by inducing the host's stress responses to withstand the downstream toxicity caused by herbicides. This latter mechanism has the potential to contribute to the growth of non-target-site-based herbicide resistance in weeds. Microbial endophytes already contribute to herbicide detoxification in planta, and there is now significant scope to extend these interactions using synthetic biology approaches to engineer new chemical tolerance traits into crops via microbial engineering., (© 2015 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.)

Echinochloa spp. are the most important weeds in rice fields. In this research Curvularia lunata and Alternaria pellucida were isolated from these weeds and their pathogenicity effects were compared on these weeds and five rice cultivars in a completely random design with three replications in greenhouse conditions. Fungi were inoculated on weeds and rice cultivars, using spore suspension consisting of 10' spore ml(-1) of distilled water. Results indicated significant effect of Curvularia lunata and Alternaria pellucida on Echinochloa oryzicola and E. crus-galli. In the present study, effect of C. lunata on fresh weight, dry weight and height of Echinochloa species based on variance analysis table, a significant reaction was observed for height and fresh weight, but for dry weight reaction was not significant. The effect of A. pellucida on fresh weight, dry weight and height of Echinochloa species based on variance analysis table, a significant reaction was observed for all the three traits. Also, rice cultivars did not show any significant reaction to C. lunata and A. pellucida. The results showed that in comparison between effect of Curvularia lunata and Alternaria pellucida on Echinochloa spp., disease rating caused by A. pellucida on E. oryzicola and E. crusalli was more than disease rating caused by C. lunata and these species of weed were more susceptible to A. pellucida. However, A. alternata can be considered as a better promising bioherbicide to control Echinochloa spp.

Antimicrobial, phytotoxic, and insecticidal activity of 30 fungal isolates obtained from leaves of weeds and wild herbaceous plants was assessed. Antibacterial, antifungal, phytotoxic, and insecticidal activity was found in over 50, 40, 47, and 40% of the isolates, respectively. These findings may be important for toxicological assessment of potential mycoherbicides, as well as provide a basis for investigation of the patterns of development of phyllosphere communities affected by fungal metabolites.

Plant pathogenic yeast were isolated from infected weeds that occur in cereal crops. On the basis of morphological, physiological and biochemical properties the yeast isolated from sow thistle and dandelion have been identified as Rhodosporidium diobovatum Newell & Hunter and Rhodotorula sp. In the experiment the yeast caused pathological process on the weeds, from which they are isolated, on other types of weeds, but also on wheat, oat and soybean.

During extensive surveys in fields heavily infested by broomrape in the Trakya Region-Turkey, a different new fungus, Aspergillus alliaceus, was isolated from the infected broomrape. It is aimed to investigate whether or not it is really a pathogen for Orobanche. The fungi was exposed to a greenhouse environment in order to assess its pathogenicity and virulence against Orobanche cernua. In addition, infection tests on Orobanche seeds were also performed under laboratory conditions. The fungus was subjected using two different methods, exposure to a liquid culture with conidial solution and a sclerotial solid culture with fungal mycelia. Cytological studies were carried out at light, TEM and SEM levels. The results show that the sclerotial solid culture with fungal mycelia quickly caused necrosis and was more effective than the other type. It also greatly diminished attachments, tubercles, and caused the emergence of shoots and an increase in the total shoot number of Orobanche. In addition, both when the fungi was exposed to both soil and used to contaminate sunflower seeds, its pathogenicity was more effective. Consequently, it was determined that A. alliaceus was an effective potential biological control of broomrape throughout its life cycle from dormant seed to mature plant., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Endophytic fungi play an important role in terrestrial ecosystem, while little is known about those in hemi-parasitic plants, a group of special plants which absorb nutrients from its hosts by haustoria. The relationship of the endophytes in the two parts of the bipartite systems (hemiparasites together with their hosts) is also poorly understood. Endophytic fungi of a hemi-parasitic plant Macrosolen tricolor, and its host plant Camellia oleifera were investigated and compared in this study. M. tricolor contained rich and diversified endophytic fungi (H' = 2.829), which consisted mainly of ascomycetes, distributed in more than ten orders of four classes (Sordariomycetes, Dothideomycetes, Leotiomycetes and Eurotiomycetes) besides Incertae sedis strains (23.2 % of total). In addition, 2.2 % of isolates were identified to be Basidiomycota, all of which belonged to Agaricomycetes. Obvious differences were observed between the endophytic fungal assembles in the leaves and those in the branches of M. tricolor. The endophytic fungi isolated from C. oleifera distributed in nearly same orders of the four classes of Ascomycota and one class (Agaricomycetes) of Basidiomycota as those from M. tricolor with similar proportion. For both M. tricolor and C. oleifera, Valsa sp. was the dominant endophyte species in the leaves, Torula sp. 1 and Fusarium sp. 1 were the dominant endophytic fungi in the branches. The similarity coefficient of the endophyte assembles in the two host was 64.4 %. Canonical correspondence analysis showed that the endophyte assembles of M. tricolor and C. oleifera were significantly different (p < 0.01).

Spatial expansion of root hemiparasitic Pedicularis kansuensis in Bayanbulak Grassland of Xinjiang Uygur Autonomous Region (China) has caused great loss of herbage yield and has threatened the local livestock industry. Current management practices using manual eradication and chemical control have been proved problematic. Arbuscular mycorrhizal (AM) fungi have been suggested to be potential biocontrol agents against a number of plant pests, but experimental evidence is lacking against weedy P. kansuensis. In this study, we tested the hypothesis that inoculation with AM fungi will cause growth depression in P. kansuensis and reduce its damage to host plants. Based on the confirmation of AM status and host community of the hemiparasite in the field, a pot cultivation experiment was conducted to test the influence of an AM fungus (Glomus mosseae) on growth of P. kansuensis and the parasitized host (Elymus nutans). AM colonization was observed in roots of P. kansuensis, but the levels were much lower than those of its adjacent host species. A negative correlation between AM levels and the numbers of haustoria was detected for the field samples of the hemiparasite. Strong suppression of haustorium formation, a significant reduction in plant dry weight (DW), as well as marked reduction in the survival rate of P. kansuensis after inoculation with AM fungi was observed. In contrast, inoculation with G. mosseae increased root DW and whole plant DW of parasitized host plants. Our findings demonstrated significantly repressive effects of AM fungi on growth performance of P. kansuensis with and without the presence of a host. The potential of AM fungi as biocontrol agents against the damaging hemiparasite was confirmed.

A total of 26 soil samples from saline soils of Haryana were collected. Based on their electrical conductivity (EC) values, which varied from 1.04 to 21.00 dS m(-1), the soils were categorized into non-saline soils (EC 0-2 dS m(-1)), weakly saline soils (EC 2-4 dS m(-1)), saline soils (EC 4-8 dS m(-1)), strongly saline soils (EC 8-16 dS m(-1)), and very strongly saline soils (EC >16 dS m(-1)). The pH values of these soil samples ranged from 6.03 to 8.62, while organic C, total N, and available P were in the range of 0.06-0.94%, 0.07-0.15%, and 0.11-0.29 μg g(-1) soil, respectively. As a measure of the impact of salinity on free-living N(2) fixers and their activity, the total bacterial populations on four media (Jensen's nitrogen-free medium, malate medium, Burk's medium, and soil extract agar medium) decreased from 6.12 to 3.70 log CFU g(-1) soil with increasing salinity level. PCR amplification of the nifH region of the DNA from 234 selected morphotypes from all the media showed the presence of nifH in 71 isolates. Out of these, 37% of the isolates were obtained using Jensen's medium; 35, 28, and 21% of the isolates were obtained using soil extract medium, Burk's medium, and malate medium, respectively. The majority of the free-living N(2) fixers (67%) were Gram negative. Apart from the acetylene reduction assay (ARA) activity in these isolates, other beneficial traits like ammonia excretion and indole acetic acid (IAA) production were also present. A decreasing trend in the activities was observed with increasing salinity levels. Isolates JN6, BP8, and MJ4 showed the highest ARA activity, ammonia excretion, and IAA production. The performance of isolates like BNC2 with good ARA activity, ammonia excretion, and IAA production and isolated from a very strongly saline soil should be further evaluated under high-saline conditions., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The ecology of weed plants includes their interactions with soil microorganisms, such as mutualistic partners that may contribute to their adaptation and competitive success in the agricultural fields. Despite the importance of microorganisms to plant growth, knowledge on weed-symbiont associations is still incipient compared to crops. Thus, a survey for the presence of arbuscular mycorrhiza (AM) and dark septate endophyte (DSE) associations in the roots of 50 weed species was done in three distinct areas during the dry and rainy seasons. We found that 41 and 29 out of the 50 species were associated with AM fungi and DSE, respectively, and 27 species presented both associations. All the plant species not forming AM belong to families thought to be nonmycorrhizal, such as Amaranthaceae, Commelinaceae, Brassicaceae, and Cyperaceae. The most common morphotype of AM observed was the Arum-type. No significant differences were found in root length colonization between the areas or seasons. For 19 species surveyed, this is the first report on their mycorrhizal status.

The stages of studying bacterial diseases of crops and weeds at various farming systems have been characterized, biological properties have been investigated and pathogens identified using traditional and modern molecular genetic methods of research.

Five strains of gram negative bacteria, isolated from soybean (LPPA 221(T), 222 and 223) and weeds (LPPA 816 and 1442), were analyzed by a polyphasic approach. The isolates showed variation in their phenotypic traits and were placed in the Pseudomonas fluorescens lineage, based on 16S rRNA gene sequence phylogeny, as a single but well separated cluster. MLSA analysis based on gyrB and rpoD sequences clustered the strains in a single branch in the Pseudomonas syringae group, and revealed P. viridiflava as closest relative. DNA-DNA hybridizations showed medium levels of DNA-DNA relatedness with the type strain of P. viridiflava (50%) and lower levels (<32%) with other type strains of the P. syringae group, supporting classification within a novel species of the genus Pseudomonas. The strains can be distinguished from species of the P. syringae group by the fatty acid C17:0 cyclo that is present in a low amount (2.5%) and from P. viridiflava by their inability to assimilate d-tartrate and d-sorbitol, and by the formation of red colonies on TTC medium. For this new species, the name Pseudomonas asturiensis sp. nov. is proposed. The type strain is LPPA 221(T) (=LMG 26898(T)=CECT 8095(T))., (Copyright © 2013 Elsevier GmbH. All rights reserved.)

The symptoms of bacterial diseases of the associated weeds have been identified and described in the wheat crops grown in different farming systems. On the basis of its morphological, biochemical and serological properties the agent isolated from frost-blite, barnyard grass, wild radish, couch grass, bottle-brush, bindweed and sow thistle has been identified as Pseudomonas syringae. Serological affinity between the weed bacteria and the agent of bacterial diseases of cereals has been established.

Parthenium hysterophorus L. is an obnoxious weed of the family asteraceae recognized for its detrimental effects and significant economic losses to agriculture. In this study 42 endophytic streptomycetes strains were isolated from its roots and leaves. The isolates were identified by morphological, microscopic, biochemical and physiological characterization as members of genus Streptomyces. In 16S rRNA gene sequencing the selected isolates exhibited maximum similarity with Streptomyces rochei (99%), Streptomyces litmocidini (99%), Streptomyces enissocaesili (99%), Streptomyces djakartensis (99%), Streptomyces olivaceus (99%), Streptomyces spp (99%), Streptomyces plicatus (99%), Streptomyces geysiriensis (99%) and Streptomyces vinaceusdrappus (99%). In biological screening the crude extracts of 12 strains exhibited significant antimicrobial activity against multi drug resistant nosocomial pathogens including Pseudomonas, Enterobacter, Bacillus, Escherichia coli, Staphlococcus aureus and Candida albicans. In chemical screening by thin layer chromatography (TLC) the extracts exhibited an impressive diversity of the bioactive secondary metabolites. Additionally high performance liquid chromatography (HPLC-UV) chromatographs revealed many impressive peaks of unidentified bioactive metabolites. As such this is a first study reporting the isolation, identification and screening of endophytic Streptomyces from the invasive weed. The results provide an insight into an untapped endophytic environment yet to be explored which might be a promising source of lead antimicrobial agents.

The increased reproductive potential, size, shoot allocation, and growth rate of weedy plants may result from reduced resource allocation to other aspects of plant growth and defense. To investigate whether changes in resource allocation occurred during domestication or the evolution of weediness, we compared the mycorrhizal responsiveness, growth, and drought tolerance of nine native ruderal, nine agriculturally weedy (four U.S. weedy and five Australian weedy), and 14 domesticated populations (eight ancient landraces and six improved cultivars) of the common sunflower (Helianthus annuus). Domesticated sunflower cultivars were less drought tolerant, but had higher plant growth and fecundity and coarser roots than wild populations. There were no changes in level of drought tolerance between improved cultivars and ancient landrace plants, but there was an increase in allocation to flowers with recent selection. Weedy populations were intermediate between domesticated cultivars and native ruderal populations for plant growth rate, root architecture, and drought tolerance. Weedy populations benefited most from mycorrhizal inoculation by having fewer wilted leaves and wetter soil. Overall, we found that trade-offs between drought tolerance and several aspects of plant growth, including growth rate, allocation to flowering, and root architecture, govern evolution during sunflower domestication and the invasion of disturbed habitat., (© 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.)

Greenhouse and field studies were performed to examine the growth responses and possible phytoremediation capacity towards heavy metals of several Brassicaceae (Brassica alba, Brassica carinata, Brassica napus and Brassica nigra) and Poaceae (durum wheat and barley). Soils used featured total concentrations of Cr, Cu, Pb and Zn largely exceeding the maximum levels permitted by the Italian laws. Different organic amendments were tested such as a compost and the plant growth-promoting rhizobacterium Bacillus licheniformis. In the greenhouse experiment, plant length, leaf area index and shoots dry matter were evaluated periodically for the Brassicaceae examined. Whereas plant length, grains production, weight of 1,000 seeds, ear fertility and tiller density were determined under field conditions at the end of the crop cycle for wheat and barley. In general, the species tested appeared to be tolerant to high heavy metal concentrations in soil, and slightly significant differences were found for all parameters considered. A marked growth increase was shown to occur for Brassicaceae cultivated on compost- and bacillus-amended contaminated soils, with respect to non-amended contaminated soils. With some exception, higher growth parameters were measured for wheat and barley plants cropped from contaminated soils in comparison to non-contaminated soils. Further, bacillus amendment enhanced the length of wheat and barley plants in both non-contaminated and contaminated soils, while different effects were observed for the other parameters evaluated.

This study is aimed at assessing culturable diazotrophic bacterial diversity in the rhizosphere of Prosopis juliflora and Parthenium hysterophorus, which grow profusely in nutritionally-poor soils and environmentally-stress conditions so as to identify some novel strains for bioinoculant technology. Diazotrophic isolates from Prosopis and Parthenium rhizosphere were characterized for nitrogenase activity by Acetylene Reduction Assay (ARA) and 16S rRNA gene sequencing. Further, the culture-independent quantitative PCR (qPCR) was performed to compare the abundance of diazotrophs in rhizosphere with bulk soils. The proportion of diazotrophs in total heterotrophs was higher in rhizosphere than bulk soils and 32 putative diazotrophs from rhizosphere of two plants were identified by nifH gene amplification. The ARA activity of the isolates ranged from 40 to 95 nmol ethylene h(-1) mg protein(-1). The 16S rRNA gene analysis identified the isolates to be members of alpha, beta and gamma Proteobacteria and firmicutes. The qPCR assay also confirmed that abundance of nif gene in rhizosphere of these two plants was 10-fold higher than bulk soil.

This study was carried out to determine the fungal pathogens on Chenopodium album L., Cirsium arvense (L.) Scop., Convolvulus arvensis L., Cynodon dactylon (L.) Pers., Delphinium consolida L., Portulaca oleracea L., Rumex crispus L., Solanum nigrum L., Sorghum halepense (L.) Pers. and Xanthium strumarium L. which were common weed species of agricultural areas. Surveys were conducted in May-June and August-September in 2004-2005 growing seasons. During the surveys density and frequency of the above mentioned weed species were also determined and number of infected plants was counted in each sampling area. Infected weed samples were collected from each sampling point and brought to the laboratory in polyethylene bags and the pathogens were identified at genus or species level. As a result of two year surveys, ten fungal pathogens were determined on eight weed species. The most important fungal pathogens determined on common weed species were as follow; Peronospora farinosa (Fr.) Fr. on C. album, and Septoria convolvuli DC., Erysiphe convolvuli DC., and Puccinia punctiformis (Strauss) Roehrl. on C. arvensis. These fungal diseases were observed mainly on the weeds located at the borders of fields. Infection rates of these pathogens reached up to 21.2% in some of the survey areas. Further studies should be conducted to evaluate the efficacy of these pathogen under in vitro and in vivo conditions.