Phosphate solubilization by Trichoderma koningiopsis (NBRI-PR5) under abiotic stress conditions

Abstract

Phosphate (P) solubilizing fungi contribute considerably in microbial phosphate mobilization. However, effects of different abiotic stresses on P solubilization mechanisms in Trichoderma are largely unexplored. In the present study we selected a P solubilizing Trichoderma to study the mechanism of P solubilization under alkaline and drought conditions. Among 33 Trichoderma isolates (NBRI-PR1–NBRI-PR33), NBRI-PR5 was selected after screening for stress tolerance, antagonistic activity against phyto-pathogens and P solubilization. The selected strain, Trichoderma koningiopsis (NBRI-PR5) was characterized and identified using ITS and tef1 sequencing (Accession no. JN375992). Results show that NBRI-PR5 uses different mechanisms of P solubilization under in-vitro alkaline and drought conditions. NBRI-PR5 produced organic acids for solubilizing insoluble tri-calcium phosphate (TCP) at high pH stress. In drought conditions NBRI-PR5 accumulated poly-phosphate in its mycelia and produced alkaline phosphatase enzyme for P solubilization. The study concludes that T. koningiopsis employs different mechanisms of P solubilization in different stress conditions and therefore, it can be used in management of stressed soils. Keywords: Phosphate solubilization, Trichoderma koningiopsis, Drought stress, Alkaline stress