Solubilisation of Phosphate and Micronutrients by Trichoderma harzianum and Its Relationship with the Promotion of Tomato Plant Growth

Rui-Xia Li; Feng Cai; Guan Pang; Qi-Rong Shen; Rong Li; Wei Chen

doi:10.1371/journal.pone.0130081

Solubilisation of Phosphate and Micronutrients by Trichoderma harzianum and Its Relationship with the Promotion of Tomato Plant Growth

PLoS One. 2015 Jun 25;10(6):e0130081. doi: 10.1371/journal.pone.0130081. eCollection 2015.

Authors

Rui-Xia Li¹, Feng Cai², Guan Pang³, Qi-Rong Shen², Rong Li², Wei Chen²

Affiliations

¹ Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China.
² Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, China; National Engineering Research Center for Organic-based Fertilizers, Nanjing, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, Nanjing, China.
³ National Engineering Research Center for Organic-based Fertilizers, Nanjing, China.

Abstract

Trichoderma harzianum strain SQR-T037 is a biocontrol agent that has been shown to enhance the uptake of nutrients (macro- and microelements) by plants in fields. The objective of this study was to investigate the contribution of SQR-T037 to P and microelement (Fe, Mn, Cu and Zn) nutrition in tomato plants grown in soil and in hydroponic conditions. Inoculation with SQR-T037 significantly improved the biomass and nutrient uptake of tomato seedlings grown in a nutrient-limiting soil. So we investigated the capability of SQR-T037 to solubilise sparingly soluble minerals in vitro via four known mechanisms: acidification by organic acids, chelation by siderophores, redox by ferric reductase and hydrolysis by phytase. SQR-T037 was able to solubilise phytate, Fe2O3, CuO, and metallic Zn but not Ca3(PO4)2 or MnO2. Organic acids, including lactic acid, citric acid, tartaric acid and succinic acid, were detected by HPLC and LC/MS in two Trichoderma cultures. Additionally, we inoculated tomato seedlings with SQR-T037 using a hydroponic system with specific nutrient deficiencies (i.e., nutrient solutions deficient in P, Fe, Cu or Zn and supplemented with their corresponding solid minerals) to better study the effects of Trichoderma inoculation on plant growth and nutrition. Inoculated seedlings grown in Cu-deficient hydroponic conditions exhibited increases in dry plant biomass (92%) and Cu uptake (42%) relative to control plants. However, we did not observe a significant effect on seedling biomass in plants grown in the Fe- and Zn-deficient hydroponic conditions; by contrast, the biomass decreased by 82% in the P-deficient hydroponic condition. Thus, we demonstrated that Trichoderma SQR-T037 competed for P (phytate) and Zn with tomato seedlings by suppressing root development, releasing phytase and/or chelating minerals. The results of this study suggest that the induction of increased or suppressed plant growth occurs through the direct effect of T. harzianum on root development, in combination with indirect mechanisms, such as mineral solubilisation (including solubilisation via acidification, redox, chelation and hydrolysis).

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Micronutrients*
Phosphates*
Plant Development / physiology*
Plant Roots / growth & development*
Soil Microbiology
Solanum lycopersicum / growth & development*
Trichoderma*

Substances

Micronutrients
Phosphates

Grants and funding

This research was supported by the National Key Technology R&D Program of the Ministry of Science and Technology (2013BAD20B05 and L0201400202), the Priority Academic Program Development of the Jiangsu Higher Education Institutions (PAPD), the 111 project (B12009), the Agricultural Ministry of China (201103004) and the National Key Basic Research Program of China (2015CB150506). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.