A newly-isolated Cd-loving Purpureocillium sp. strain YZ1 substantially alleviates Cd toxicity to wheat.

Background: Environmental approaches for minimizing wheat grain Cd are urgently in need in many parts of the world. While metal-removing strategies like phytoextraction or soil-washing are not suitable to the scenario of farmland Cd pollution, rhizoremediation which aims to reduce crops' Cd uptake by using microbial technology has shown great potentials. Methods and results: In this study, a filamentous fungus strain YZ1 was isolated from wheat farmland soil, which is affiliated to Purpureocillium sp. based on morphological and phylogenetical evidence. The strain YZ1 had a minimum inhibitory concentration of 1 mM Cd and was able to survive at 100 mM Cd, with maximum biomass at 0.4 mM Cd. Comparative transcriptomics showed that little changes in cellular transcriptional patterns occurred at 0.4 mM Cd relative to the control, and substantial transcriptional changes could be detected mainly in substance metabolism/transport genes at 2 mM Cd. Pot culture experiments showed that YZ1 rhizo-inoculation ameliorated Cd stress to wheat substantially, leading to a significant reduction by 23.3% to 26.0% in Cd concentration of wheat seedlings. Further, molecular evidence indicated that YZ1 may colonize the wheat root and impact wheat Cd response by modulating wheat's Cd-associated genes, mainly TaEXPA2, TaVP1, TaMRP3, TaPCS1 and TaTM20, while no effect of YZ1 on culture medium pH or Cd bioavailability was observed. Conclusions: A fungal strain YZ1 showing Cd-loving nature was isolated. The strain YZ1 can be a promising candidate for rhizoremediation of Cd-contaminated farmland in wheat-production areas. [ABSTRACT FROM AUTHOR]