TaSTP13 contributes to wheat susceptibility to stripe rust possibly by increasing cytoplasmic hexose concentration

Baoyu Huai,Zhensheng Kang,Jie Liu,Xiaobo Wei,Qian Yang,Qinglin Pan

doi:10.1186/s12870-020-2248-2

Baoyu Huai, Zhensheng Kang + Show 4 more

Open Access

https://doi.org/10.1186/s12870-020-2248-2

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Abstract

BackgroundBiotrophic fungi make intimate contact with host cells to access nutrients. Sugar is considered as the main carbon sources absorbed from host cells by pathogens. Partition, exchanges and competition for sugar at plant-pathogen interfaces are controlled by sugar transporters. Previous studies have indicated that the leaf rust resistance (Lr) gene Lr67, a natural mutation of TaSTP13 encoding a wheat sugar transport protein, confers partial resistance to all three wheat rust species and powdery mildew possibly due to weakened sugar transport activity of TaSTP13 by heterodimerization. However, one major problem that remains unresolved concerns whether TaSTP13 participates in wheat susceptibility to rust and mildew.ResultsIn this study, expression of TaSTP13 was highly induced in wheat leaves challenged by Puccinia striiformis f. sp. tritici (Pst) and certain abiotic treatments. TaSTP13 was localized in the plasma membrane and functioned as homooligomers. In addition, a functional domain for its transport activity was identified in yeast. Suppression of TaSTP13 reduced wheat susceptibility to Pst by barley stripe mosaic virus-induced gene silencing (VIGS). While overexpression of TaSTP13 promoted Arabidopsis susceptibility to powdery mildew and led to increased glucose accumulation in the leaves.ConclusionsThese results indicate that TaSTP13 is transcriptionally induced and contributes to wheat susceptibility to stripe rust, possibly by promoting cytoplasmic hexose accumulation for fungal sugar acquisition in wheat-Pst interactions.

Highlights

Biotrophic fungi make intimate contact with host cells to access nutrients
Cloning and sequence analysis of TaSTP13 The TaSTP13 gene was amplified from the Puccinia striiformis f. sp. tritici (Pst)-infected Suwon 11 (Su11) cDNA sample using reverse transcription polymerase chain reaction (RT-PCR)
They are identical to the LR67sus protein form the wheat cultivar Thatcher in amino acid sequence, while they are different from the Lr67res protein form Thatcher RL6077 [15] at the two key amino acid residues: Gly144 and Val387 (Additional file 3: Figure S3)

Summary

Introduction

Biotrophic fungi make intimate contact with host cells to access nutrients. Sugar is considered as the main carbon sources absorbed from host cells by pathogens. Sucrose is a major long-distance translocation form of photoassimilate that is exported from the phloem to the apoplasm of sink tissues under hydrostatic pressure, and subsequently imported into sink cells to sustain heterotrophic metabolism and growth by specific transport proteins [5]. This export step is mediated by SWEET proteins, sucrose transporters, or monosacharide transporters (if extracellular invertases are available) [3, 5].

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