Role of Sulphate Transporter (PiSulT) of Endophytic Fungus Serendipita indica in Plant Growth and Development

Sulfur is an important macronutrient required for the growth, development of plants and is a key component of many metabolic pathways. We have functionally characterized a high-affinity sulphate transporter (PiSulT) from an endophytic fungus Serendipita indica. The PiSulT belongs to the major facilitator superfamily (MFS) of membrane transporter. The PiSulT functionally complements the yeast sulphate transporter mutant HK14. PiSulT is a high-affinity sulphate transporter, having Km 15M. We found enhanced expression of PiSulT in external fungal hyphae which helps the fungus in the acquisition of sulphate from the soil. When knockdown (KD)-PiSulT-P.indica colonized with the plant, it results in an 8-fold reduction in the transfer of sulphate to the colonized plants as compared to the plants colonized with the WT S. indica, which suggests that PiSulT is playing a role in sulphate transfer from soil to host plant. Further, plants colonized with the WT S. indica were found to be healthy in comparison to the plants colonized with the KD-PiSulT-P.indica. Additionally, S. indica colonization provides a positive effect on total sulfur content and on plant metabolites like sulfate ions and glutathione, particularly under low sulphate condition. We observed that the expression of sulfur assimilation pathway genes of S. indica and plant is dependent on the availability of sulphate and on the colonization with the plant. Our study highlights the importance of PiSulT in the improvement of sulfur nutrition of host plant particularly under low sulphate condition and in plant growth development. This study will open new vistas to use S. indica as a bio-fertilizer in the sulphate deficient field to improve crop production. One-Sentence SummaryHigh-affinity sulphate transporter of Serendipita indica (PiSulT) transfer sulphate from soil to plant under low sulphate condition and improve plant growth and development.