Probiotics for Plants? Growth Promotion by the Entomopathogenic Fungus Beauveria bassiana Depends on Nutrient Availability

Abstract

Cultivation of crops requires nutrient supplements which are costly and impact the environment. Furthermore, global demands for increased crop production call for sustainable solutions to increase yield and utilize resources such as nutrients more effectively. Some entomopathogenic fungi are able to promote plant growth, but studies over such effects have been conducted under optimal conditions where nutrients are abundantly available. We studied the effects of Beauveria bassiana (strain GHA) seed treatment on the growth of maize (Zea mays) at high and low nutrient conditions during 6 weeks in greenhouse. As expected, B. bassiana seed treatment increased plant growth, but only at high nutrient conditions. In contrast, the seed treatment did not benefit plant growth at low nutrient conditions where the fungus potentially constituted a sink and tended to reduce plant growth. The occurrence of endophytic B. bassiana in experimental plant tissues was evaluated by PCR after 6 weeks, but B. bassiana was not documented in any of the above-ground plant tissues indicating that the fungus-plant interaction was independent of endophytic establishment. Our results suggest that B. bassiana seed treatment could be used as a growth promoter of maize when nutrients are abundantly available, while the fungus does not provide any growth benefits when nutrients are scarce.

Inoculation with entomopathogenic fungi reduces seed contamination, improves seed germination and growth of chilli seedlings

“…Our results showed that inoculation with EF produced seedlings with greater height and weight. Results from this study is in agree with others, where EF was able to promote plant growth parameters (Bamisile et al, 2018;Enkerli, 2016, Tall andMeyling, 2018), but in other cases, differences in growth parameters were not significant (Tefera and Vidal, 2009).…”

Endophytic establishment of Beauveria bassiana and Metarhizium anisopliae in maize plants and its effect against Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) larvae

“…Renuka et al (2016) observed that stems of Z. mays were also colonized by B. bassiana; however, the availability and persistence on the plant tissues varied according to their age (high persistence in young tissues). Despite several authors have demonstrated that B. bassiana as endophyte of maize, others have been revealed that after the inoculation of this EPF on maize seeds, no colonization of plant tissues was obtained (Tall and Meyling 2017).…”

Influence of the plant interacting entomopathogenic fungus Beauveria bassiana on parasitoid host choice-behavior, development, and plant defense pathways

“…There are multiple reports of effects on insects where retrieving of the fungus from the host plant failed, maybe due to the limited growth of the fungus within the host plant [ 13 ]. Also, methods for screening and quantifying endophytic colonization vary greatly and come with several caveats such as contamination problems [ 12 ] and underestimation of colonization [ 74 ]. Endophytic colonization has in previous studies been assumed without testing for colonization [ 55 , 56 ].…”