Effects of cross host species inoculation of nitrogen‐fixing endophytes on growth and leaf physiology of maize

Abstract

Plants that grow and thrive under abiotic stress often do so with the help of endophytic microorganisms. Although nitrogen-fixing (diazotrophic) endophytes colonize many wild plants, these natural relationships may be disrupted in cultivated crop species where breeding and genotype selection often occur under conditions of intensive fertilization and irrigation. Many energy crops including corn may still benefit from diazotrophic endophyte inoculations allowing for more efficient biomass production with less input of petroleum-derived fertilizer. A selection of diazotrophic endophytes isolated from willow (Salix sitchensis, Sitka willow) and poplar (Populus trichocarpa, black cottonwood) growing in nutrient-poor river sides were used as inoculum in three experiments testing the effect on plant growth and leaf level physiology of a sweet corn variety under various levels of applied nitrogen fertilizer. We report substantial growth promotion with improved leaf physiology of corn plants in response to diazotrophic endophyte inoculations. Significant gains of early biomass with a greater root : shoot ratio were found for plants receiving endophytic inocula over the uninoculated control groups regardless of the nitrogen level. Furthermore, inoculated plants exhibited consistently higher rates of net CO 2 assimilation than did those without endophytic inoculation. These results have beneficial implications for enhanced plant growth in a low-input system on nutrient-poor sites. The immediate increase of root mass observed in endophyte inoculated plants has the potential to provide better establishment and early growth in resource-limited environments. The initial results of this study also indicate that the beneficial effect from endophytes isolated from poplar and willow species is not restricted to the species from which they were initially isolated.

Consortium Application of Endophytic Bacteria and Fungi Improves Grain Yield and Physiological Attributes in Advanced Lines of Bread Wheat

“…These endophytes either as single strain or multi-strain inoculum have previously exhibited mutualistic behavior when added to other plant species including grasses, corn, rice, Douglas-fir and a variety of crop plants (Xin et al, 2009;Knoth et al, 2013;Knoth et al, 2014;Khan et al, 2012;Khan et al, 2015;DaSilveria et al, 2016). Combined application of endophytes can result in larger effects than those possible with individual inoculations (Knoth et al, 2013;Knoth et al, 2014;Rogers et al, 2012). In this study, the bacterial and fungal strains of different endophytes (Bacillus sp.…”

Increased Biomass of Nursery-Grown Douglas-Fir Seedlings upon Inoculation with Diazotrophic Endophytic Consortia

“…In this preliminary study, we chose a consortia of diazotrophic endophytes, originally isolated from poplar and willow trees [20][21][22], because they had shown robust growth-promoting activity with agricultural crops, grasses and poplar plants grown under abiotic stress [22,[39][40][41]. Our objective was to determine if these endophytes enhance the growth of Douglas-fir seedlings under nutrient-poor conditions.…”

Isolation and Characterization of Endophytic Bacteria Associated with Roots of Jojoba (<i>Simmondsia chinensis</i> (Link) Schneid)

“…2 . This difference may be due to very different environmental conditions, even if they are desert plants 11,17 . In our study, the abundance of endophytes decreased with soil alkalinity in site 20 where pH was 9.19 and had the lowest population density (Table 1).…”

“…However, bacteria yielding the maximum number of mechanisms to promote plant growth were collected at the sampling sites where soil pH was both more acid (6.18) and alkaline (9.19) ( Table 1), which could be related to the production of root exudates acting as chemical signals to attract endophytic bacteria. It has been reported that there is increased production of root exudates when soil pH is acidic (pH 6) or alkaline (pH 8) 17 . Only eight representative isolates were chosen for having multiple plant-growth promoting properties for further analysis.…”