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Cinnamic acid (CA) is an allelochemical that inhibits the growth of root promoting soil microorganisms. To prevent the growth of soil microbes, CA modulates several metabolic pathways in host plants and soil microbes. The aim of the current study was to investigate the effect of CA on maize root growth, exudation of secondary metabolites and its interaction with beneficial endophyte Pz11. The endophyte Pz11 was isolated from the roots of drought stressed Asphodelus tenuifolius (wild onion). The Pz11 strain was identified as Fusarium culmorum by homology of the internal transcribed spacer (ITS) region of 18 S rDNA sequence. The F. culmorum Pz11 produced phytostimulants and signaling compounds, such as indole-3-acetic acid (IAA), flavonoids and sugars. Moreover, the strain have effectively colonized the roots of maize and subsequently enhanced the growth of its host plants. On the contrary, application of CA has reduced root growth in maize seedlings as well as root colonization ability of F. culmorum Pz11. Also, maize seedlings exposed to CA exude low quantities of flavonoids and polyphenols. In conclusion, CA reduces the maize root growth and exudation of secondary metabolites, which may affects its ability to attract plant growth promoting endophytic fungi., (Copyright © 2018 Elsevier Masson SAS. All rights reserved.)

Inula britannica L., family Asteraceae, is used in traditional Chinese and Kampo Medicines for various diseases. Flowers or the aerial parts are a rich source of secondary metabolites. These consist mainly of terpenoids (sesquiterpene lactones and dimmers, diterpenes and triterpenoids) and flavonoids. The isolated compounds have shown diverse biological activities: anticancer, antioxidant, anti-inflammatory, neuroprotective and hepatoprotective activities. This review provides information on isolated bioactive phytochemicals and pharmacological potentials of I. britannica.

Ginseng has long been widely used for its therapeutic potential. In our current study, we investigated the impact of abiotic stress induced by infrared (IR) radiations and sodium silicate on the upregulation of antioxidant and anti-tyrosinase levels, as well as the total phenolic and total flavonoid contents of the Korean ginseng (Panax ginseng C.A. Meyer) variety Yeonpoong. The RSM-based design was used to optimize ultrasonic-assisted extraction time (1–3 h) and temperature (40–60 °C) for better anti-tyrosinase activity and improved antioxidant potential. The optimal extraction results were obtained with a one-hour extraction time, at a temperature of 40 °C, and with a 1.0 mM sodium silicate treatment. We recorded maximum anti-tyrosinase (53.69%) and antioxidant (40.39%) activities when RSM conditions were kept at 875.2 mg GAE/100 g TPC, and 3219.58 mg catechin/100 g. When 1.0 mM sodium silicate was added to the media and extracted at 40 °C for 1 h, the highest total ginsenoside content (368.09 mg/g) was recorded, with variations in individual ginsenosides. Ginsenosides Rb1, Rd, and F2 were significantly affected by extraction temperature, while Rb2 and Rc were influenced by the sodium silicate concentration. Moreover, ginsenoside F2 increased with the sodium silicate treatment, while the Rg3-S content decreased. Interestingly, higher temperatures favored greater ginsenoside diversity while sodium silicate impacted PPD-type ginsenosides. It was observed that the actual experimental values closely matched the predicted values, and this agreement was statistically significant at a 95% confidence level. Our findings suggest that the application of IR irradiation in hydroponic systems can help to improve the quality of ginseng sprouts when supplemented with sodium silicate in hydroponic media. Optimized extraction conditions using ultrasonication can be helpful in improving antioxidant and anti-tyrosinase activity. [ABSTRACT FROM AUTHOR]

Fungal endophytes are not widely known for their role in bioactive metabolite production and salinity stress alleviation in different crop plants. Presently, we investigated the salt stress (NaCl, KCl, and H2SO4) mitigation capabilities of fungal endophyte Candida membranifaciens (FH15) isolated from Euphorbia milii L. The pure culture filtrate (CF) of C. membranifaciens revealed siderophore production and solubilization of phosphate, with high levels of indoleacetic acid (IAA: 35.8µg/mL), phenolics (70 µg/mL), and flavonoids (50 µg/mL) by using a UV spectrophotometer. The LC/MS analysis of the CF showed different phenols and flavonoids that were identified as Salicylic acid, Baicalein, Aconitic acid, Feruloylquinic acid, Coniferyl aldehyde hexoside, Pentose, Chlorogenic acid, Myricetin, Propoxyphene, and Amino-flunitrazepam. Inoculation of maize seedlings with C. membranifaciens significantly (p = 0.05) enhanced the fresh and dry biomass, carotenoid, and chlorophyll contents under 100 mM salt stress conditions. Similarly, the catalase, peroxidase activity, phenols, proline flavonoids and relative water contents (RWC) of the maize plants were enhanced. More interestingly, the inoculation of C. membranifaciens on maize revealed a higher endogenous IAA level as compared to non-inoculated control plants. Endophyte C. membranifaciens inoculation on maize seedlings under salt stress revealed a 20.87% and 16.60% increase in fresh and dry biomass, as well as significantly enhanced root shoot length and allied growth attributes, in addition to an alleviation of the adverse effects of salinity stress. Conclusively, endophytic C. membranifaciens significantly enhanced the growth attributes of maize and mitigated the adverse effects of salinity stress. Such endophytic fungal strain could be used for further field trails to enhance agricultural productivity and facilitate sustainable agricultural practices. [ABSTRACT FROM AUTHOR]

Salt stress is one of the leading growth-retarding factors among all the abiotic stresses that affect 30% of worldwide-irrigated land. Researchers are employing different strategies and approaches to manage this problem. However, some of the strategies are costly while others are time consuming. On the other hand, the use of endophytes is pragmatic, cheap and eco-friendly. This work investigated the potential role of endophytic Aspergillus oryzae CM1 in the mitigation of salinity-induced stress in Abelmoschus esculentus. NaCl stress altered the morphological and physio-biochemical attributes as well as phytohormones in okra plants. The inoculation of endophytic A. oryzae CM1 significantly increased growth attribute (shoot/root length), biomass (fresh/dry weight), chlorophyll (a, b) and carotenoids contents, IAA, total soluble sugar and relative water content (RWC) in okra. The malondialdehyde (MDA) and proline content in the okra seedlings increased by 91.21% and 38.83%, respectively. Increase in phenolic and flavonoid contents were witnessed in NaCl stressed okra plants inoculated with isolate CM1. NaCl stress (100 mM) decreased IAA content in leaves (32.57%), stem (22.01%) and roots (19.65%) of the control okra seedlings. However, an increase in IAA contents in leaves (143.04%), stem (115.32%), and roots (60.28%) were observed in okra plants inoculated with isolate CM1. By investigating the chemical profile of A. oryzae CM1 crude extract, we found sinapiic acid, 3,4-dimethyl-caffeic-acid, feruloylquinic-acid, coniferylaldehyde hexoside, cycloolivil, glucaric-acid, moracenin, kuwanon, sinapyl aldehyde, sophocarpine, propoxyphene and myricetin. Thus, NaCl stress causes an adverse effect on okra, however, the colonization of endophytic A. oryzae improves NaCl tolerance by ameliorating the physio-biochemical attributes and phytohormones production in host plant species. [ABSTRACT FROM AUTHOR]

The current climate changes in the form of global warming are one of the leading threats to agricultural crops (including soybean and sunflower). To enable the crops to cope with the heat stress, innovative steps are needed to be taken as soon as possible. Fungal endophytes are known to secrete secondary metabolites that promote the growth of host plants under stress conditions. Therefore, we have isolated endophytic fungus from Euphorbia indica (a wild desert plant) and tested it for plant growth promoting activities. The culture filtrate of the fungal strains exhibited the presence of secondary metabolites. Higher amounts of indole acetic acid (IAA), salicylic acid (SA), flavonoids, and phenolics have been found in the culture filtrate. The 18S rDNA sequence homology and phylogenetic analysis revealed that the isolate is Aspergillus flavus. Soybean and sunflower seedlings were inoculated with the identified A. flavus. The A. flavus-associated seedlings along with the control (without A. flavus) were monitored for thermal stress resistance in a growth chamber, operated at 25°C and 40°C. Control seedlings exposed to high temperature stress had higher levels of abscisic acid (ABA), proline, and lower levels of phenols, flavonoids, catalase, and ascorbic acid oxidase. Similarly, a higher reduction in chlorophyll, root-shoot length, and dry weight has been noticed in the control seedlings. The results suggested the usefulness of A. flavus in host plant growth promotion under heat stress conditions. [ABSTRACT FROM AUTHOR]

We have isolated an endophytic fungus with heat stress alleviation potential from wild plant Euphorbia indica L. The phylogenetic analysis and 18S rDNA sequence homology revealed that the designated isolate was Aspergillus japonicus EuR-26. Analysis of A. japonicus culture filtrate displayed higher concentrations of salicylic acid (SA), indoleacetic acid (IAA), flavonoids, and phenolics. Furthermore, A. japonicus association with soybean and sunflower had improved plant biomass and other growth features under high temperature stress (40°C) in comparison to endophyte-free plants. In fact, endophytic association mitigated heat stress by negotiating the activities of abscisic acid, catalase, and ascorbic acid oxidase in both soybean and sunflower. The nutritional quality (phenolic, flavonoids, soluble sugars, proteins, and lipids) of the A. japonicus-associated seedlings has also improved under heat stress in comparison to endophyte-free plants. From the results, it is concluded that A. japonicus can modulate host plants growth under heat stress and can be used as thermal stress alleviator in arid and semiarid regions of the globe (where mean summer temperature exceeds 40°C) to sustain agriculture. [ABSTRACT FROM AUTHOR]

The association between microbes and plant roots involves a complex chemical dialogue featured by IAA and flavonoids in addition to other signals. Current study is focused on the role of IAA and flavonoids as essential elements of the chemical dialogue between an endophytic fungus and maize roots. The strain was isolated from the leaves of Withania somnifera and was identified as Aspergillus fumigatus greenish by 18S rDNA sequence. Culture filtrate of the strain contained phyotstimulant (IAA, ammonia and ACC) and signaling compounds including IAA, flavonoids and flavonols. The strain effectively colonized the maize roots and enhanced its growth. In order, to determine the effect of IAA and flavonoids on the ability of the endophyte to colonize maize roots, we inhibited the release of IAA and flavonoids in maize separately which reduced the colonization of endophyte in maize root to 66% and 55% of the untreated control. Similarly, application of IAA in combination with endophyte enhanced root colonization by 90% in zone of cell division, 66% in the zone of elongation and 30% in the zone of maturation. These findings determined that IAA and flavonoids are among the key players of the complex chemical dialogue between plant root and fungal endophyte. [ABSTRACT FROM AUTHOR]

Beneficial bacterialiving in the rhizosphere pose several implications on plant growth promotion and are highly desirable for sustainable agriculture. In the current study, we explored the ameliorative capacity ofLeifsonia xyliSE134, a plant growth-promoting rhizobacteria (PGPR), against copper (Cu) stress on tomato grown under elevated Cu levels of 50 and 100 mM. Initially,L. xyliSE134 modulated innate gibberellins (GAs) and indole-3-acetic acid (IAA) metabolism in response to elevated Cu toxicity. The IAA contents increased, whereas that of bioactive GAs decreased in relation to Cu concentration gradient in the broth media. Furthermore, exposure to elevated Cu caused detrimental effects on the physiological attributes as revealed by attenuated shoot length, root length, stem diameter, shoot dry weight, root dry weight, and chlorophyll content in non-inoculated tomatoes as compared toL. xyliSE134 inoculated plants. The growth rescuing effect ofL. xyliSE134 may be attributed to the modulation of endogenous amino acids contents in plants, such as glutamic acid, threonine, phenylalanine, glycine, proline, and arginine. Moreover,L. xyliSE134 inoculation stimulated total polyphenol and flavonoid content, reduced super oxide dismutase activity, strongly inhibited Cu, and increased phosphorus and iron content in plants grown under elevated Cu stress. In the absence of Cu toxicity,L. xyliSE134 significantly enhanced amino acid content, improved total flavonoids, and increased phosphorus content, thus resulting in higher plant growth. [ABSTRACT FROM PUBLISHER]

Abstract: Endophytic fungi are little known for exogenous gibberellins (GAs) production and plant growth promotion under salt stress conditions. We isolated 13 endophytic fungi from soybean roots, which were screened on Waito-C rice for plant growth promoting capacity. Endophytic strain, GMH-1a exhibited maximum growth during screening and thus was investigated for GAs production and host plant interaction. GMH-1a was identified as a new strain of Aspergillus fumigatus sp. LH02 through phylogenetic analysis of 18S rDNA sequence. Analysis of GMH-1a culture filtrate showed presence of GA4 (24.8ng/ml), GA9 (1.2ng/ml) and GA12 (9.8ng/ml). Soybean plants inoculated with GMH-1a significantly increased shoot length, shoot fresh and dry biomass, leaf area, chlorophyll contents and photosynthetic rate under salt stress (70 and 140mM) as compared to non-inoculated plants. GMH-1a inoculated plants had contained significantly lower endogenous abscisic acid (ABA) and elevated free proline, salicylic acid (SA) and jasmonic acid (JA) contents in comparison to their respective control treatments. Isoflavones, quantified through excessive HPLC analysis, showed that GMH-1a inoculated plants with/without salt stress contained higher isoflavones than non-inoculated plants and with/without NaCl stress. This novel endophytic fungus has reprogrammed soybean metabolism to improve plant growth and increase isoflavone contents under salt stress. [Copyright &y& Elsevier]

Contamination of agricultural land with heavy metal is a serious biological and environmental issue. Such threat can be challenged by exploring the plant symbiotic microbes that can improve plant growth through phyto-hormones secretion and chromate chelation. In the current study, chromate resistant rhizospheric Staphylococcus arlettae strain MT4 was isolated from the rhizosphere of Malvestrum tricuspadatum L. The strain showed potential to secrete phytohormones and plant growth promoting secondary metabolites under induced chromate stress, making it a best suitable candidate in chromate stress alleviation. Moreover, the rhizobacterium MT4 significantly promoted the net assimilation and relative growth rate of sunflower grown in the presence of chromate (100 ppm). Chromate stress alleviation strategy of MT4 strain was three-fold. MT4 alleviated chromate stress and promoted the sunflower growth by suppressing the chromate intake by the host, modulating phytohormones and strengthening of the host's antioxidant system. The improved antioxidant system was confirmed by noticing lower ROS accumulation and improved ROS scavenging, lower peroxidase activity and higher accumulation of phenols and flavonoids. • Staphylococcus arlettae MT4 significantly promotes net assimilation and relative growth rate of Cr stressed sunflower. • MT4 associated seedlings had reduced uptake and higher reduction of Cr. • Strong antioxidant system of MT4 associated seedlings immuned them to grow healthy under Cr stress. [ABSTRACT FROM AUTHOR]