Bacterial Endophytes of Spring Wheat Grains and the Potential to Acquire Fe, Cu, and Zn under Their Low Soil Bioavailability

Wheat grains are usually low in essential micronutrients. In resolving the problem of grain micronutritional quality, microbe-based technologies, including bacterial endophytes, seem to be promising. Thus, we aimed to (1) isolate and identify grain endophytic bacteria from selected spring wheat varieties (bread Oksamyt myronivs'kyi, Struna myronivs'ka, Dubravka, and emmer Holikovs'ka), which were all grown in field conditions with low bioavailability of microelements, and (2) evaluate the relationship between endophytes' abilities to synthesize auxins and the concentration of Fe, Zn, and Cu in grains. The calculated biological accumulation factor (BAF) allowed for comparing the varietal ability to uptake and transport micronutrients to the grains. For the first time, bacterial endophytes were isolated from grains of emmer wheat <i>T. turgidum</i> subsp. <i>dicoccum</i>. Generally, the 12 different isolates identified in the four varieties belonged to the genera <i>Staphylococcus</i>, <i>Pantoea</i>, <i>Sphingobium</i>, <i>Bacillus</i>, <i>Kosakonia</i>, and <i>Micrococcu</i>s (NCBI accession numbers: MT302194-MT302204, MT312840). All the studied strains were able to synthesize the indole-related compounds (IRCs; max: 16.57 µg∙mL^-1) detected using the Salkowski reagent. The IRCs produced by the bacterial genera <i>Pantoea</i> spp. and <i>Bacillus</i> spp. isolated from high-yielding Oksamyt myronivs'kyi and Holikovs'ka grains may be considered as one of the determinants of the yield of wheat and its nutritional characteristics.