Search

Abiotic stressors are global limiting constraints for plant growth and development. The most severe abiotic factor for plant growth suppression is salt. Among many field crops, maize is more vulnerable to salt, which inhibits the growth and development of plants and results in low productivity or even crop loss under extreme salinity. Consequently, comprehending the effects of salt stress on maize crop improvement, while retaining high productivity and applying mitigation strategies, is essential for achieving the long-term objective of sustainable food security. This study aimed to exploit the endophytic fungal microbe; Aspergillus welwitschiae BK isolate for the growth promotion of maize under severe salinity stress. Current findings showed that salt stress (200 mM) negatively affected chlorophyll a and b, total chlorophyll, and endogenous IAA, with enhanced values of chlorophyll a/b ratio, carotenoids, total protein, total sugars, total lipids, secondary metabolites (phenol, flavonoids, tannins), antioxidant enzyme activity (catalase, ascorbate peroxidase), proline content, and lipid peroxidation in maize plants. However, BK inoculation reversed the negative impact of salt stress by rebalancing the chlorophyll a/b ratio, carotenoids, total protein, total sugars, total lipids, secondary metabolites (phenol, flavonoids, tannins), antioxidant enzyme activity (catalase, ascorbate peroxidase), and proline content to optimal levels suitable for growth promotion and ameliorating salt stress in maize plants. Furthermore, maize plants inoculated with BK under salt stress had lower Na+, Cl− concentrations, lower Na+/K+ and Na+/Ca2+ ratios, and higher N, P, Ca2+, K+, and Mg2+ content than non-inoculated plants. The BK isolate improved the salt tolerance by modulating physiochemical attributes, and the root-to-shoot translocation of ions and mineral elements, thereby rebalancing the Na+/K+, Na+/Ca2+ ratio of maize plants under salt stress. [ABSTRACT FROM AUTHOR]

Heavy metal (HM) contamination in the soil and accumulation in plants poses a serious threat to crops and human health. HMs such as cadmium, mercury, lead and arsenic are widely acknowledged for their adverse effects on plants such as chlorosis, necrosis, low food quality and crop yields. Endophytic fungi secrete secondary metabolites and enhance the plant's ability to tolerate stressful conditions. However, the role of most fungal endophytes in their host plant growth or production of metabolites under HM stress conditions needs further understanding. In the present study, we studied the HM stress alleviation capability of the endophytic fungus, Paecilomyces lilacinus (MRF), isolated from the roots of Justicia adathoda. We studied two heavy metals, namely lead and cobalt. The culture filtrate (CF) of P. lilacinus revealed IAA (68.17 µg/mL), phenols (43.31 µg/mL), flavonoids (40.59 µg/mL), sugar content (97.83 µg/mL) and proline (17 µg/mL). Additionally, DPPH-free radical scavenging activity and the antibacterial potential against Salmonella typhi and Shigella sonnei of the CF demonstrated positive results. The gas chromatography mass spectrometry analysis of the CF manifested different constituents, including (1) Trichloromethane, (2) 3,7,11,15-Tetramethyl-2-hexadecen-1-ol, (3) phytol, (4) 1,2-Benzenedicarboxylic acid, (5) bis(2-ethylhexyl) ester, (6) squalene and (7) Cyclotrisiloxane Hexamethyl. Moreover, the plant growth-promoting activity of the P. lilacinus (MRF) strain revealed a robust increase in root and shoot growth, and the fresh and dry weight of S. lycoprsicum. Further, the IAA, phenols, flavonoids, sugar, proline, relative water content and protein contents also increased in the S. lycoprsicum inoculated with P. lilacinus as compared to the control plants. The present study revealed that the inoculation of P. lilacinus alleviates the damages of HM stress and improves the physicochemical characteristics of S. lycoprsicum. [ABSTRACT FROM AUTHOR]

Parthenium hysterophorus L. is considered an obnoxious weed due to its rapid dispersal, fast multiplications, and agricultural and health hazards. In addition to its physio-molecular and phytotoxic allelochemical usage, this weed most probably uses endophytic flora as an additional line of defense to deal with stressful conditions and tolerate both biotic and abiotic stresses. The aim of this article is to report the diversity of endophytic flora (fungi and bacteria) in P. hysterophorus and their role in the stress mitigation (biotic and abiotic) of other important crops. Various endophytes were reported from P. hysterophorus and their roles in crops evaluated under biotic and abiotic stressed conditions. These endophytes have the potential to alleviate different stresses by improving crops/plants growth, development, biomass, and photosynthetic and other physiological traits. The beneficial role of the endophytes may be attributed to stress-modulating enzymes such as the antioxidants SOD, POD and APX and ACC deaminases. Additionally, the higher production of different classes of bioactive secondary metabolites, i.e., flavonoids, proline, and glutathione may also overcome tissue damage to plants under stressed conditions. Interestingly, a number of medicinally important phytochemicals such as anhydropseudo-phlegmcin-9, 10-quinone-3-amino-8-O methyl ether 'anhydropseudophlegmacin-9, 10-quinone-3-amino-8-O methyl ether were reported from the endophytic flora of P. hysterophorus. Moreover, various reports revealed that fungal and bacterial endophytes of P. hysterophorus enhance plant growth-promoting attributes and could be added to the consortium of biofertilizers. [ABSTRACT FROM AUTHOR]

Climate change is a major cause of the world’s food security problems, and soil salinity is a severe hazard for a variety of crops. The exploitation of endophytic fungi that are known to have a positive association with plant roots is preferred for improving plant growth, yield, and overall performance under salt stress. The current study thus rationalized to address how salt stress affected the growth, biochemical properties, antioxidant capacity, endogenous indole-3-acetic acid (IAA), and the ionic status of maize associated with endophytic fungus (Stemphylium lycopersici). According to the findings, salt stress reduced chlorophyll a and b, total chlorophyll, total protein, sugars, lipids, and endogenousIAAlevels. Enhanced values of chlorophyll a/b ratio, carotenoids, secondary metabolites (phenol, flavonoids, and tannins), antioxidant enzyme activity (catalase, ascorbate peroxidase), proline, and lipid peroxidation were noticed in maize plants under salt stress. Increased ionic content of Na+, Cl−, Na+/K+, and Na+/Ca2+ ratio, as well as decreased Ca2+, K+, Mg2+, N, and P contents, were also found in salt-stressed maizeplants. In comparison to thenon-saline medium,endophyticassociation promoted the antioxidant enzyme activities (798.7 U/g protein; catalase activity, 106 U/g protein; ascorbate peroxidaseactivity), IAA content (3.47 mg/g FW), andphenolicsandflavonoids (88 and 1.68µg/g FW, respectively), and decreased MDA content (0.016 nmol/g FW), Na+ ioncontent(18mg/gdryweight), Cl− ion (16.6 mg/gdryweight), and Na+/K+ (0.78) and Na+/Ca2+ (1.79) ratios, in maize plants under salt stress, whereas Ca2+, K+, Mg2+, N, and P contents were increased in maize plants associated with S. lycopersici under salt stress. Current research exposed the role of S. lycopersici as an effective natural salt stress reducer and maize growth promoter; hence, it can be used as a biofertilizer to ameliorate salt stress tolerance in crops along with better growth performance in saline regions. [ABSTRACT FROM AUTHOR]

High temperature is one of the compelling ecological stresses faced by the plants owing to anthropogenic activities of mankind. Recently, endophytic fungi are considered to be a novel tool to counteract the consequences of thermal stress in crops. Owing to the problem, we isolated fungal endophytes from Dryopteris blanfordii and their growth favoring potential in rice seedlings. Endophytic fungi have the proficiency to secrete plant growth stimulating secondary metabolites that help the host plants to restore growth under harsh environments. The isolated Penicillium glabrum (DryR-30) helped the host plant species, i.e. Glycine max L. and Helianthus annuus L. under thermal stress. P. glabrum associated with G. max and H. annuus exposed to 40°C not only boosted their host growth attributes (total biomass, plant height and chlorophyll contents), but also significantly curtailed the synthesis of reactive oxygen species and lipids peroxidation. Moreover, the abscisic acid (ABA) and proline concentrations were significantly reduced, while the accumulation of ROS-degrading enzymes, such as catalase (CAT), peroxidase (POD), ascorbic acid oxidase (AAO), glutathione reductase (GR) and superoxide dismutase (SOD) were increased in P. glabrum-associated crops. Additionally, the protein, lipid and sugar contents in tested plants were also improved. These stirring findings suggest that P. glabrum can be applied to food crops as a thermal stress alleviation tool. [ABSTRACT FROM AUTHOR]

In this study, an endophytic fungus, Aspergillus niger CSR3, was isolated from Cannabis sativa. The culture filtrate (CF) was initially screened for growth-promoting activities such as the presence of siderophores, phosphate solubilization, and the production of indole acetic acid (IAA) and gibberellins and was further assayed for its ability to promote the growth of mutant waito-C rice. Nearly all plant growth attributes examined (root-shoot length, biomass, and chlorophyll content) were significantly enhanced by treatment with CSR3. This growth promotion action was due to the presence of various types of gibberellins (GAs) and IAA in the endophyte CF. Moreover, the presence of GA pathway genes (P50-1, P450-3, P450-4, ggs2, and des) was confirmed by means of semi-quantitative RT-PCR. Finally, the application of CSR3 spore suspension with uniconazole and yucasin on maize seedlings revealed that, similar to exogenous IAA and GA3, CSR3 has the potential to alleviate the inhibitory effect of these inhibitors. [ABSTRACT FROM AUTHOR]

Endophytic fungi are potential sources of secondary metabolites; however, they are little known for phytohormones secretion and amelioration of plant growth under abiotic stresses. We isolated a novel endophyte from the roots of Cucumis sativus and identified it as a strain of Exophiala sp. by sequencing internal transcribed spacer/large subunit rDNA and phylogenetic analysis. Prior to identification, culture filtrate (CF) of Exophiala sp. has shown significant growth promotion of Waito-C [a gibberellins (GAs)-deficient mutant cultivar] and Dongjin-byeo (normal GAs biosynthesis cultivar) rice seedlings. CF analysis of Exophiala sp. showed the presence of physiologically active GAs (GA1, GA3, GA4 and GA7) and inactive GAs (GA5, GA8, GA9, GA12 and GA20). Exophiala sp. had higher GAs in its CF than wild-type strain of Gibberella fujikuroi except GA3. Influence of Exophiala sp. was assessed on cucumber plant's growth and endogenous abscisic acid (ABA), salicylic acid (SA) and bioactive GAs under salinity and drought stresses. Exophiala sp.-treated plants have shown significantly higher growth and rescued the host plants from stress promulgated water deficit, osmotic and cellular damage. The altered levels of stress-responsive ABA showed low level of stress confined to endophyte-applied plants than control. Elevated levels of SA and bioactive GAs (GA3 and GA4) in endophyte-associated plants suggest stress-modulating response toward salinity and drought. In conclusion, symbiotic relations between Exophiala and cucumber have reprogrammed the host plant growth under abiotic stresses, thus indicating a possible threshold role of endophytic fungi in stress alleviation. This study could be extended for improving agricultural productivity under extreme environmental conditions. [ABSTRACT FROM AUTHOR]

The growth promoting activities of the isolated endophyte Aspergillus terreus from Aloe barbendsis was studied in the salt stressed Pennisetum glaucum (pearl millet). A significant (P = 0.05) increase in the root-shoot lengths, fresh and dry weights and chlorophyll content of pearl millet seedlings was noticed after colonization by A. terreus under normal conditions. At 100 mM NaCl stress and A. terreus inoculation, the growth rate of pearl millet seedlings were significantly (P = 0.05) inhibited. Furthermore, the IAA production, relative water content (RWC), chlorophyll, soluble sugar, phenol and flavonoid contents were significantly decreased, whereas proline content and lipid peroxidation were increased. On the contrary, pearl millet seedlings inoculated with A. terreus retained significantly (P = 0.05) higher amounts of RWC, chlorophyll, soluble sugar, phenol and flavonoid contents under 100 mM salt stress. The higher IAA production in A. terreus associated seedlings rescued the plant growth and development under salt stress. Moreover, the LC MS/MS analysis of A. terreus cultural filtrate revealed the presence of quinic acid, ellagic acid, calycosin, wogonin, feruloylquinic acid, caffeic acid phenylethyl ester, D-glucoside, myricetin, propoxyphene and aminoflunitrazepam. The results of the study conclude that innoculation of A. terreus improves the NaCl tolerance in pearl millet by ameliorating the physicochemical attributes of the host plants. • A potent entophytic fungus isolated from the Aloe barbendsis was tested for plant growth promotion under salinity stress. • The culture filtrate of Aspergillus terreus helped the millet under salinity by influencing the plant endogenous hormones. • Also, A. terreus supported the growth of millet under salinity stress through modulation of secondary metabolites. • The A. terreus acted as a salt stress reliever in millet indicated its potential to be used as bio-fertilizer under stress. [ABSTRACT FROM AUTHOR]