Native Rhizospheric and Endophytic Fungi as Sustainable Sources of Plant Growth Promoting Traits to Improve Wheat Growth under Low Nitrogen Input

Akram H Mohamed; Fayrouz H Abd El-Megeed; Naziha M Hassanein; Sameh H Youseif; Peter F Farag; Saleh A Saleh; Basel A Abdel-Wahab; Amnah Mohammed Alsuhaibani; Yosra A Helmy; Ahmed M Abdel-Azeem

doi:10.3390/jof8020094

Native Rhizospheric and Endophytic Fungi as Sustainable Sources of Plant Growth Promoting Traits to Improve Wheat Growth under Low Nitrogen Input

J Fungi (Basel). 2022 Jan 19;8(2):94. doi: 10.3390/jof8020094.

Affiliations

¹ Department of Microbial Genetic Resources, National Gene Bank, Agricultural Research Center (ARC), Giza 12619, Egypt.
² Microbiology Department, Faculty of Science, Ain Shams University, Abbasia 11566, Egypt.
³ Agricultural Microbiology Research Department, Soils, Water and Environment Research Institute, Agricultural Research Center (ARC), Giza 12619, Egypt.
⁴ Department of Medical Pharmacology, College of Medicine, Assiut University, Assiut 7111, Egypt.
⁵ Department of Pharmacology, College of Pharmacy, Najran University, P.O. Box 1988, Najran 55461, Saudi Arabia.
⁶ Department of Physical Sport Science, College of Education, Princess Nourah bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia.
⁷ Department of Animal Hygiene, Zoonoses and Animal Ethology, Faculty of Veterinary Medicine, Suez Canal University, Ismailia 41522, Egypt.
⁸ Botany and Microbiology Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt.

Abstract

Wheat crops require effective nitrogen fertilization to produce high yields. Only half of chemical N₂ fertilizers are absorbed into plants while the rest remains in the soil, causing environmental problems. Fungi could maximize nitrogen absorption, and from an environmental and biodiversity point of view, there is an urgent necessity for bioprospecting native fungi associated with wild plants growing in harsh environments, e.g., St. Katherine Protectorate (SKP) in the arid Sinai. Recovered taxa, either endophytic and/or rhizospheric, were screened for their plant growth-promoting (PGP) traits. Eighteen fungal isolates (15 rhizospheric and 3 endophytic) belonging to anamorphic ascomycetes were recovered from 9 different wild plants, and their PGP traits (indole-3-acetic acid [IAA] production, phosphate solubilization, siderophore production, and hydrolytic enzyme production) were measured. Rhizospheric isolate NGB-WS14 (Chaetosphaeronema achilleae) produced high levels of IAA (119.1 μg mL^-1) in the presence of tryptophan, while NGB-WS 8 (Acrophialophora levis) produced high IAA levels (42.4 μg mL^-1) in the absence of tryptophan. The highest phosphate-solubilizing activity (181.9 μg mL^-1) was recorded by NGB-WFS2 (Penicillium chrysogenum). Endophytic isolate NGB-WFE16 (Fusarium petersiae) exhibited a high percentage level of Siderophore Unit (96.5% SU). All isolates showed variability in the secretion of extracellular hydrolytic enzymes. Remarkably, all isolates had antagonistic activity (55.6% to 87.3% suppression of pathogen growth) against the pathogenic taxon Alternaria alternata (SCUF00001378) in the dual-assay results. Out of the 18 isolates, 4 rhizospheric and 1 endophytic isolate showed significant increases in shoot dry weight and shoot nitrogen and chlorophyll content of wheat plants subjected to low inputs of chemical nitrogen (N) fertilizers (50% reduction) compared with the non-inoculated control in a pot experiment. Potent 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. This study considered the first report of endophytic fungi of Cheilanthes vellea, a wild plant with PGPF which improves wheat growth. These results recommend using PGPF as inoculants to alleviate low nitrogen fertilization.

Keywords: IAA; crop protection; endophytes; fertilization; fungi; phosphorus; rhizosphere; wild plants.