The new CaSn gene belonging to the snakin family induces resistance against root-knot nematode infection in pepper
The new CaSn gene belonging to the snakin family induces resistance against root-knot nematode infection in pepper
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属于蛇科的新CaSn基因诱导辣椒对根结线虫感染的抵抗力
DOI：
10.1007/s12600-011-0149-5
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发表时间：
2011-04-01
期刊：
影响因子：
1.4
通讯作者：
Xie, Bingyan
中科院分区：
文献类型：
--
作者：
Mao, Zhenchuan;Zheng, Jingyuan;Xie, Bingyan
该基因属于辣椒(Capsicum Annuum)蛇毒蛋白家族，编码一种新的抗菌肽，对根结线虫(Meloidogyne spp.)感染。利用抑制性消减杂交(SSH)技术分离和克隆了csN基因，并在大肠杆菌中进行了表达和鉴定。CaSnakin蛋白是由23个氨基酸残基组成的信号肽、14个氨基酸残基组成的酸性多肽(等电点 = 4.18)和66个氨基酸残基组成的成熟蛋白，其相对分子质量为7.03kDa。该序列含有12个保守的半胱氨酸，形成6个二硫键。CaSnakin与马铃薯(Solanum Tuberosum)的多肽Snakin-2(StSN2)高度同源；CaSnakin与StSN2的同源性为88.5%。系统进化树分析表明，该基因属于蛇毒蛋白亚家族II。实时定量逆转录聚合酶链式反应(RT-qPCR)结果表明，根结线虫侵染诱导了csN基因的表达，在芽、茎、根和叶中也有表达。在大肠杆菌中表达的CaSnakin蛋白在体外对自生线虫和根结线虫具有较强的抗菌活性。此外，病毒诱导的基因沉默(VIGS)结果表明，csN基因参与了植物对线虫的防御。综上所述，线虫侵染可以激活csN基因，并在寄主防御中发挥重要作用。据我们所知，这是第一次报道蛇毒基因在植物防御线虫中的作用。此外，csN基因是从辣椒中分离到的蛇毒蛋白家族的第一个基因。
The new CaSn gene belonging to the snakin family in pepper (Capsicum annuum) encodes a novel antimicrobial peptide and responds to root-knot nematode (Meloidogyne spp.) infection. CaSn was isolated and cloned using suppression subtractive hybridization (SSH), and the gene was characterized and expressed in Escherichia coli. The CaSnakin protein encoded by CaSn is an antimicrobial peptide consisting of a signal peptide of 23 amino acid residues, an acidic peptide of 14 amino acid residues (pI = 4.18), and a mature protein of 66 amino acid residues that corresponds to a molecular mass of 7.03 kDa. The peptide sequence has 12 conserved cysteines forming six disulfide bridges. CaSnakin is highly homologous to the peptide snakin-2 (StSN2) of potato (Solanum tuberosum); CaSnakin also shows 88.5% identity to StSN2. Phylogenetic tree analysis indicated that the CaSn gene belongs to subfamily II of the snakin family. Real-time quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) results showed that the CaSn gene was induced and expressed evidently by root-knot nematode infection; CaSn is also expressed in buds, stems, roots and leaves. The CaSnakin protein expressed in E. coli showed strong antimicrobial activity against free-living nematodes (Caenorhabditis elegans) and root-knot nematodes in vitro. In addition, the virus-induced gene silencing (VIGS) results revealed that the CaSn gene participates in the defense of plants against nematodes. In conclusion, the CaSn gene can be activated by nematode infections, and it plays an important role in host defense. As far as we know, this is the first investigation reporting the role of a snakin gene in the defense of plants against nematodes. In addition, the CaSn gene is the first gene of the snakin family isolated from pepper.