Expression of type 1 metallothionein gene from Medicago sativa and analysis of its function in stress tolerance

doi:10.11686/cyxb2017230

Abstract

Abstract: A gene sequence was obtained from Medicago sativa “Nongjing No. 1” cDNA via PCR amplification using specific primers designed from the cDNA sequence of Type 1 Metallothionein gene (MET1, GenBank accession number: AF189766.1) in M. sativa. This gene is assigned as MsMT1. The total length of this gene fragment is 228 bp and it encodes 75 amino acids. The nucleotide sequence of MsMT1 has 99% homology with MET1. Multiple sequence alignment and the phylogenetic tree showed a high similarity between the MsMT1 and the MT1 in other plants. MsMT1 gene expression was analyzed in different organs of M. sativa by qRT-PCR, with higher quantities found in roots and cotyledons. MsMT1 gene expression was examined in M. sativa seedlings under different concentrations of salt solution and pH values. The results revealed that the expression quantity of MsMT1 gene changed with the saline or alkaline solution concentration, indicating that MsMT1 is associated with stress tolerance. The MsMT1 gene was transformed into M. sativa plant through Agrobacterium tumefaciens-mediated method. The positive transformation was further confirmed by the kanamycin resistance test and the Northern blot test confirmed that MsMT1 was successfully expressed in the transgenic M. sativa. Wild type and transgenic M. sativa seedlings were treated with different concentrations of NaCl or NaHCO₃ which revealed that the transgenic plants had higher stress tolerance than wild type plants. The results of this study highlight the MsMT1 gene can increase plants tolerance to stress.

Key words: Medicago sativa, metallothionein, expression characterization, stress tolerance

XU Chang, HE Hao, LI Guo-liang, JIN Shu-mei. Expression of type 1 metallothionein gene from Medicago sativa and analysis of its function in stress tolerance[J]. Acta Prataculturae Sinica, 2018, 27(4): 89-97.

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