Analysis of the phosphate solubilization efficiency of different phosphorus sources by Endophytic fungus Serendipita indica under arsenic stress

Abstract

Background and Aims

Despite the competitive behavior of arsenate (AsV) with inorganic phosphate (Pi), S. indica association enhances plant growth under arsenic stress by reducing arsenic bioavailability. However, at the same time, the capability of S. indica to improve P-solubilization and its utilization under arsenic stress has not been explored.

Methods

We first examined the S. indica ability to tolerate arsenic by measuring its growth and biomass in the presence of various P sources under arsenic stress. Further, S. indica culture is investigated for the acidification and acid phosphatase (ACPase) activity when supplied with various P sources under arsenic stress.

Results

This study reveals that P-solubilization process is linked to the acidification and secretion of ACPase enzyme in S. indica. Our data suggest that arsenic does not hamper the acidification and extracellular acid phosphatase (ACPase) activity of the fungus, which is essential for P-solubilization by releasing free Pi from bound insoluble phosphorus (P) sources. However, at high arsenic availability, phosphate utilization by the fungus was reduced significantly due to arsenic toxicity and competition, leading to reduced fungal growth. Besides this, we also found that the P-solubilization process is not affected by arsenic. This Psolubilization occurs due to enhanced ACPase activity and a drop in pH in the surrounding medium.

Conclusions

The study suggests that the fungus can solubilize and utilize diverse P sources available in the soil without the hindrance of arsenic, and therefore, S. indica can be a good candidate for arsenic remediator for crop plants with P benefits.

Graphical Abstract