Effects of mycorrhizal species on colonization, polyphenol levels, and growth characteristics of Allium porrum

Authors: Malik, Nasir; Nunez, Alberto; McKeever, Lindsay; Olanya, Modesto

Submitted to: Journal of Plant Protection Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2018
Publication Date: 5/10/2018
Citation: Malik, N.S., Nunez, A., Mckeever, L., Olanya, O.M. 2018. Effects of mycorrhizal species on colonization, polyphenol levels, and growth characteristics of Allium porrum. Journal of Plant Protection Research. 58(1):83-90. 10.24425/119122.
DOI: https://doi.org/10.24425/119122

Interpretive Summary: Mycorrhizal symbiosis is known to increase plant growth under limited water and nutrient supplies. However, our previous studies had shown that mycorrhizal symbiosis with different plant species could increase the levels of certain polyphenols even under optimum water and nutrient supplies. A natural step forward from previous studies was to determine if all of the species of mycorrhizal fungi similarly increase different species of polyphenols or whether different mycorrhizal fungi species have different effects on polyphenols of specific plant cultivars. Therefore this study was conducted where seven different mycorrhizal species were individually inoculated to leek seedlings. Eight weeks after inoculation, the leek plants were harvested and analyzed for polyphenol levels. In addition plant height and root/shoot dry weights were measured. These results clearly showed that increases in the levels of specific polyphenols were different depending on the specific mycorrhizal fungi species used for inoculation. For example levels of a particular Kaempferol derivative increased 1123% in plants inoculated with Glomus geosporum, but the increase in this polyphenol was only 310% in plants inoculated with Gigaspora margarita. In addition, while plants inoculated with Glomus geosporum showed decreases in the levels of some polyphenol species, white Glomus species increased levels of all polyphenol species detected in leeks. These results therefore provide very valuable information for commercial cultivation of leeks.

Technical Abstract: The effects of different mycorrhizal fungi species (Rhizopus intraradices, Gigapora margarita, Glomus geosporum, Paraglomus occultum, Claroideoglomus claroideum, white Glomus species) on their ability to colonize leek roots (Allium porrum) and the effect of symbiosis on changes in the levels of polyphenol plant growth parameters were evaluated. There were significant differences (P<0.05) in colonization among arbuscular mycorrhizal fungi species. The greatest level of colonization was recorded on R. intraradices and the lowest level on white Glomus sp. A comparison of polyphenol levels between non-mycorrhizae leek plants and those inoculated with mycorrhiza revealed significant differences (P<0.01) as evidenced by the height values. The percentage increases in polyphenols relative to the controls ranged from 310 to 1123% on peak 2 (a derivative of kaempferol), while changes in other polyphenols due to symbiosis with different mycorrhizal species ranged from negative to as much as 590% increases. This indicates that different mycorrhizal species exhibit marked differences in the manner with which they affect levels of different polyphenols in leeks. The mycorrhizal fungi Glomus geosporum produced the maximum increases in the levels of peak 2 (1123%), but then levels of several other peaks (9-12) were decreased. On the other hand, mycorrhizal fungi Glomus species white increased the levels all the polyphenols although the increases of peak 2 (a derivative of kaempferol) were 783 percent. Significant differences (P<0.05) in plant height were also recorded, however; dry shoot weight and dry root weight varied slightly and were not significant. Even though C. claroideum and white Glomus species had lower effect on plant weight, it polyphenol levels (%) were significantly (P<0.05) higher compared to the control.