TaAMT2;3a, a wheat AMT2-type ammonium transporter, facilitates the infection of stripe rust fungus on wheat

Junpeng Jiang,Zhensheng Kang,Jing Fu,Wanlu Duan,Hua Zhuang,Jing Zhao,Xiaodong Wang,Song Tian

doi:10.1186/s12870-019-1841-8

Junpeng Jiang, Zhensheng Kang + Show 6 more

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https://doi.org/10.1186/s12870-019-1841-8

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Abstract

BackgroundAmmonium transporters (AMTs), a family of proteins transporting ammonium salt and its analogues, have been studied in many aspects. Although numerous studies have found that ammonium affects the interaction between plants and pathogens, the role of AMTs remains largely unknown, especially that of the AMT2-type AMTs.ResultsIn the present study, we found that the concentration of ammonium in wheat leaves decreased after infection with Puccinia striiformis f. sp. tritici (Pst), the causal agent of stripe rust. Then, an AMT2-type ammonium transporter gene induced by Pst was identified and designated as TaAMT2;3a. Transient expression assays indicated that TaAMT2;3a was located to the cell and nuclear membranes. TaAMT2;3a successfully complemented the function of a yeast mutant defective in NH4+ transport, indicating its ammonium transport capacity. Function of TaAMT2;3a in wheat-Pst interaction was further analyzed by barley stripe mosaic virus (BSMV)-induced gene silencing. Pst growth was significantly retarded in TaAMT2;3a-knockdown plants, in which ammonium in leaves were shown to be induced at the early stage of infection. Histological observation showed that the hyphal length, the number of hyphal branches and haustorial mother cells decreased in the TaAMT2;3a knockdown plants, leading to the impeded growth of rust pathogens.ConclusionsThe results clearly indicate that the induction of AMT2-type ammonium transporter gene TaAMT2;3a may facilitates the nitrogen uptake from wheat leaves by Pst, thereby contribute to the infection of rust fungi.

Highlights

Ammonium transporters (AMTs), a family of proteins transporting ammonium salt and its analogues, have been studied in many aspects
The results demonstrated that the relative ammonium contents in the roots increased as early as 12 hpi and were maintained at a high level throughout the infection
The relative ammonium contents in the leaves and stems significantly decreased, especially in the leaves, and reached the lowest point at 12 hpi and 36 hpi, respectively (Fig. 1a). These results revealed that the infection by stripe rust fungus greatly affected the transport and metabolism of ammonium in wheat, which led to a decline in ammonium levels in the leaves and stems and an increase in the roots

Summary

Introduction

Ammonium transporters (AMTs), a family of proteins transporting ammonium salt and its analogues, have been studied in many aspects. Numerous studies have found that ammonium affects the interaction between plants and pathogens, the role of AMTs remains largely unknown, especially that of the AMT2-type AMTs. Nitrogen is an indispensable element for all living organisms, and its uptake and utilization are the major limiting factors for plant growth and crop yield [1, 2]. Ammonium and nitrate, which are absorbed and transported into plant root cells by AMTs and NRTs (nitrate transporters) respectively, are the main plant available inorganic forms of nitrogen in soils. After transport into root cells, NH4+ is assimilated into glutamate via the glutamine synthase/glutamate synthase (GS/GOGAT) cycle for the further synthesis of organic macromolecules

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