Influence of Nitrogen Application Rate on the Importance of NO<sub>3</sub><sup>−</sup>-N and NH<sub>4</sub><sup>+</sup>-N Transfer via Extramycelia of Arbuscular Mycorrhiza to Tomato with Expression of <i>LeNRT2.3</i> and <i>LeAMT1.1</i>
Xiaocan Xie,
Zhe Huang,
Weixing Lv,
Houteng Zhu,
Guoming Hui,
Ronghua Li,
Xihong Lei,
Zhifang Li
Affiliations
Xiaocan Xie
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University (CAU), Haidian District, Yuanmingyuanxilu 2, Beijing 100193, China
Zhe Huang
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University (CAU), Haidian District, Yuanmingyuanxilu 2, Beijing 100193, China
Weixing Lv
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University (CAU), Haidian District, Yuanmingyuanxilu 2, Beijing 100193, China
Houteng Zhu
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University (CAU), Haidian District, Yuanmingyuanxilu 2, Beijing 100193, China
Guoming Hui
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University (CAU), Haidian District, Yuanmingyuanxilu 2, Beijing 100193, China
Ronghua Li
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University (CAU), Haidian District, Yuanmingyuanxilu 2, Beijing 100193, China
Beijing Key Laboratory of Growth and Developmental Regulation for Protected Vegetable Crops, Department of Vegetable Science, College of Horticulture, China Agricultural University (CAU), Haidian District, Yuanmingyuanxilu 2, Beijing 100193, China
Arbuscular mycorrhizal fungi (AMF) form mutualistic symbiotic relationships with many land plants and play a key role in nitrogen (N) acquisition. NO3−-N and NH4+-N are the main sources of soil mineral N, but how extraradical mycelial transfer affects the different N forms and levels available to tomato plants is not clear. In the present study, we set up hyphal compartments (HCs) to study the efficiency of N transfer from the extramycelium to tomato plants treated with different N forms and levels of fertilization. Labeled 15NO3−-N or 15NH4+-N was placed in hyphal compartments under high and low N application levels. 15N accumulation in shoots and the expression of LeNRT2.3, LeAMT1.1, and LeAMT1.2 in the roots of tomato were measured. According to our results, both 15NO3−-N and 15NH4+-N were transported via extraradical mycelia to the shoots of plants. 15N accumulation in shoots was similar, regardless of the N form, while a higher 15N concentration was found in shoots with low N application. Compared with the control, inoculation with AMF significantly increased the expression of LeAMT1.1 under high N and LeNRT2.3 under low N. The expression of LeAMT1.1 under high N was significantly increased when NO3—N was added, while the expression of LeNRT2.3 was significantly increased when NH4+-N was added under low N. Taken together, our results suggest that the N transfer by extraradical mycelia is crucial for the acquisition of both NO3−-N and NH4+-N by the tomato plant; however, partial N accumulation in plant tissue is more important with N deficiency compared with a higher N supply. The expression of N transporters was influenced by both the form and level of N supply.
