Endophytes <i>Aspergillus caespitosus</i> LK12 and <i>Phoma</i> sp. LK13 of <i>Moringa peregrina</i> produce gibberellins and improve rice plant growth

Abstract

Two new strains of endophytic fungi were isolated from the bark of <i>Moringa peregrina</i> and identified as <i>Aspergillus caespitosus</i> LK12 and <i>Phoma</i> sp. LK13. These endophytes were identified through amplifying polymerase chain reaction (PCR) and sequencing the 18S internal transcribed spacer of DNA extracted from both endophytes. Pure cultures of endophytic fungi were subjected to extract and isolate gibberellins (GAs). Deuterated standards of [17,17-²H₂]-GA₁, [17,17-²H₂]-GA₃, [17, 17-²H₂]-GA₄ and [17, 17-²H₂]-GA₇ were used to quantify the endophytic fungal GAs. The analysis revealed that both the endophytes are producing bioactive GAs in various quantities (ng mL⁻¹). <i>A. caespitosus</i> LK12 was producing GA₁ (54.51 ± 1.23), GA₄ (26.5 ± 0.65), and GA₇ (2.87 ± 1.23) while <i>Phoma</i> sp. LK13 was secreting GA₁ (4.8 ± 0.12), GA₃ (8.65 ± 0.21), GA₄ (23.7 ± 0.98), and GA₇ (22.7 ± 0.73). The culture filtrate (CF) of <i>A. caespitosus</i> and <i>Phoma</i> sp. significantly increased the shoot length of GAs-deficient mutant <i>waito-c</i> and normal Dongjin-beyo rice seedlings as compared to control. Application of such growth-promoting and GAs-producing endophytes can ameliorate poorly growing crop plants.