Plant growth promoting endophytic fungi Asprgillus fumigatus TS1 and Fusarium proliferatum BRL1 produce gibberellins and regulates plant endogenous hormones

Abstract

Endophytes can serve as plant growth promoters as they secret a vast array of phytohormones to support host plants. Keeping the growth promoting activity of the endophytes in view, two endophytic fungi, Asprgillus fumigatus TS1 and Fusarium proliferatum BRL1 have been isolated from the roots of Oxalis corniculata. The isolates have been screened initially for growth promoting activities, including siderophores activity, phosphate solubilization, and secreation of indole acetic acid and gibberellins. Further, the isolates have assayed for the ability to promote the growth of mutant rice Waito-C. The plants associated with TS1 and BRL1 have shown higher chlorophyll content, root-shoot length, and biomass production. The growth promoting activity of the endophytes can be attributed to the various types of GAs and IAA that have been observed in the culture filtrates of the endophytes by the Gas chromatography/mass spectrometry (GC/MS). The GC/MS analysis revealed the presence of different gibberellins concentrations (ng/ml) in TS1 and BRL1 culture filtrate, i.e. GA1 (0.091 ± 0.009, 0.392 ± 0.007), GA3 (0.324 ± 0.077, 0.089 ± 0.0007) and GA7 (0.023 ± 0.002, 0.492 ± 0.005), respectively. Besides, a significant up regulation of plant endogenous GA1 (12.443 ± 0.454 and 15.434 ± 0.245) has been obsereved in TS1 and BRL1 associated plants compared to the control. Moreover, semi quantitative RT-PCR has confirmed the presence/invovment of GA pathways genes (P50–1, P450–3, P450–4, ggs2, and des). The results conclude that the endophytes isolated in this study can ably synthesize bioactive compounds, which play an important role in plant growth promotion.