الفهرس 
REVIEW OF LITERATUREOnly 14 pages are availabe for public view
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Abstract
Abstract
Wheat crops require effective nitrogen fertilization to produce high yields. Only half of the chemical N2 fertilizers are absorbed into plants while the rest remains in the soil, causing environmental problems. So it’s necessary to develop new resources to decrease overconsumption of nitrogen fertilizers. Wild medicinal plants are a reservoir of plant growth-promoting microorganisms. The main objective of this study concentrates on the isolation, molecular identification, and characterization of potent (fungal and bacterial) rhizospheric and endophytic taxa related to some wild and medicinal plants. This study represents collected reports about microbial isolates and their role in wheat plant growth promotion. More specifically, verification for plant growth-promoting traits of these isolates such as extracellular enzymatic production, antagonistic activity against phytopathogens, IAA, siderophore production, and P solubilization were evaluated to test their influence on the biomass production of wheat plants as an important economical crop under low nitrogen input.
Preliminary screening showed that out of (388 bacteria and 18 fungi), thirty-five bacterial and eighteen fungal isolates were most potent for plant growth-promoting traits (IAA, siderophore production, and phosphate solubilization efficiency). Highest IAA (485 μg mL-1) production by endophytic isolate NGB-WE117. Highest P-solubilization (181.9 µg mL-1) by rhizospheric fungal isolate NGB-WFS2. Thirteen bacterial isolates had siderophore production of over 50% SU. Endophytic fungal isolate NGB-WFE16 exhibited 96.5 % SU. Three bacterial isolates (NGB-WE113, NGB-WE114, and NGB-WS38) showed high HCN production. The maximum pathogen inhibition (35.8 %) was achieved by endophytic isolate NGB-WE206 against Fusarium gramminerum phytopathogen. The highest antagonistic activity by 87.3 % by NGB-WFS18 has been recorded against Alternaria alternata phytopathogen.
In response to microbial isolates to promote wheat plant growth under 50 % N fertilization. Inoculation of the wheat plant by NGB-WS105 yielded significant-high shoot fresh weight (8.6 g/plant ) and dry weight (3.07 g/plant) as well as high nitrogen content (33.2 mg N /plant) compared to un-inoculated control. while inoculation by rhizospheric isolate (NGB-WFS1) yielded the highest shoot fresh weight (2.9 gm /plant) and shoot dry weight (1.20 gm /plant). Shoot N content significantly increased by inoculation with Endophytic fungal isolate NGBWFE16. Photosynthetic pigments of wheat plants leave enhanced by microbial inoculations.
Based 16S rRNA gene sequence, bacterial isolates were classified into three phyla (25 isolates belonged to Proteobacteria, 4 isolates belonged to Firmicutes and 6 isolates belonged to Actinobacteria) with 16 different genospecies (Psychrobacter, Acinetobacter, Pseudomonas, pantoea, Enterobacter, Pseudoxanthomonas, Achromobacter, Rhizobium, Brevundimonas, Staphylococcus, Bacillus, Kocuria, Citricoccus, Leucobacter, Cellulosimicrobium, and Sanguibacter ). Based on the greenhouse results, Potent fungal taxa were subjected to sequencing for molecular confirmation of phenotypic identification. The retrieved ITS sequences in this study have been deposited in GenBank under accession numbers from LC642736 to LC642740 revealing their identities as members of five different genera (Aspergillus, Botryotrichum, Chaetosphaeronema, Fusarium, and Penicillium).
These results recommended that plant growth-promoting microorganisms as inoculants to compensate for the low nitrogen fertilization with high plant productivity.