Bioactive chemical constituents produced by endophytes and effects on rice plant growth

<p>We investigated the bioactive potential of fungal endophytes isolated from the roots of <i>Glycine max</i> (L.) Merr. and <i>Cucumis sativus</i>. Initial screening results showed that endophytes, (<i>Chrysosporium pseudomerdarium</i>, <i>Aspergillus fumigates</i> and <i>Paecilomyces</i> sp., <i>Penicillium</i> sp., <i>Phoma glomerata</i>, and <i>Paecilomyces formosus</i>) were promoting the growth attributes (shoot length, chlorophyll contents, and biomass) of mutant and wild-type rice. To know whether, these endophytes were producing bioactive chemical constituents; the endophytes were grown in potato dextrose, czapek broth, and ICI mediums that resulted in varying mycelia biomass. The advance chromatographic analysis of endophytic fungal culture filtrate showed gibberellins (GA) production namely GA<sub>1</sub> (0.05–10.55 ngml<sup>−1</sup>), GA<sub>3</sub> (0.48–9.0 ngml<sup>−1</sup>), GA<sub>4</sub> (0.2–8.0 ngml<sup>−1</sup>), GA<sub>7</sub> (1.4–6.5 ngml<sup>−1</sup>), and GA<sub>9</sub> (0.03–1.05 ngml<sup>−1</sup>) while among endophytes, <i>P. glomerata</i> and <i>P. formosus</i> were highly potent in GAs production. Additionally, the endophyte's culture also contained indole-3-acetic acid (0.23–71.51 µgml<sup>−1</sup>). Furthermore, oxalic (0.009–0.3 mgl<sup>−1</sup>), quinic (0.019–0.22 mgl<sup>−1</sup>), malic (1.94–17.2 mgl<sup>−1</sup>), and citric (0.012–0.95 mgl<sup>−1</sup>) acids were also present in the endophytic cultures. The biochemical potential of endophytes greatly varied depending on nutrient source and pH, however, czapek broth rich in carbon revealed higher potential for bioactive chemical constituent's production. In conclusion, the current findings suggest that endophyte can play a vital role in essential crop plant growth by synthesizing a wide array of bioactive metabolites. Furthermore, an increased production of chemical constituents can be achieved by changing the in vitro growth conditions of endophytes</p>