Sulfur transfer from the endophytic fungus Serendipita indica improves maize growth and requires the sulfate transporter SiSulT

Area of Science:

• Plant-microbe interactions
• Fungal physiology
• Nutrient transport

Background:

• Sulfur deficiency stunts plant growth and reduces yield.
• Symbiotic fungi can enhance host plant nutrient uptake.
• Endophytic fungi like Serendipita indica offer potential for improving plant nutrition.

Purpose of the Study:

• To identify and characterize a high-affinity sulfate transporter from Serendipita indica.
• To investigate the role of this transporter in fungal and host plant sulfur nutrition.
• To explore the potential of S. indica for improving plant growth in low-sulfate environments.

Main Methods:

• Identification and functional characterization of the sulfate transporter SiSulT.
• Heterologous expression in yeast to confirm transport activity.
• RNA interference to create a SiSulT knockdown strain in S. indica.
• Colonization experiments with maize (Zea mays) under varying sulfur conditions.

Main Results:

• SiSulT expression was induced under low-sulfate conditions and complemented yeast mutants.
• Wild-type S. indica, but not the SiSulT knockdown strain, compensated for low sulfate and supported maize growth.
• Maize roots colonized by WT S. indica showed reduced expression of sulfate assimilation genes under low sulfur.

Conclusions:

• The identified sulfate transporter SiSulT is essential for S. indica's ability to improve host plant sulfur nutrition.
• S. indica facilitates sulfur uptake and assimilation in maize, alleviating sulfur deficiency stress.
• This endophyte-host interaction presents a promising strategy for sustainable agriculture in sulfur-limited soils.