Screening of Some Endophytic Fungi Strains for Zinc Biofortification in Wheat (Triticum aestivum L.)

As a vital micronutrient, zinc is essential for the optimal growth of plants that can be released from insoluble compounds by zinc-solubilizing fungi. This study aimed to investigate the efficiency of indigenous fungi in accumulation, bioconcentration, and translocation of zinc in wheat through two in vitro and greenhouse phases. In first experiment, several indigenous fungi (Trichoderma harzianum, T. longibrachiatum, Aspergillus niger, and A. ustus) were isolated from an industrial polluted area with heavy metals and screened for their ability to grow under various zinc-sulfate concentrations. Results revealed that Aspergillus spp. grew more slowly than T. harzianum which showed the maximum tolerance index than others, whereas other fungal growth was inhibited. The greenhouse phase was conducted as a factorial experiment in a completely randomized design with three replicates. Experimental factors included fungal treatments at three levels (control, inoculation with T. longibrachiatum, and A. niger), and the fungi were screened based on their superior performance in the in vitro phase and zinc sulfate application at four levels (0, 60, 300, and 600 mg L−1). Root accumulation increased at higher zinc concentration (600 mg kg−1) in wheat inoculated with T. longibrachiatum by 24% over the control. By contrast, bioconcentation factor and zinc translocation to roots and grains of inoculated plants reduced significantly under zinc concentrations by 80% and 62%. Overall, this study strengthens the idea that inoculation zinc-solubilizing strains has the potential to boost growth and could be used as bioinoculants, particularly with Trichoderma spp. for wheat biofortification addressing the nutritional issues in both plants and humans.