苹果NBS-LRR1 基因的鉴定与表达分析

 NBS-LRR 蛋白是植物细胞内普遍存在的主要抗性蛋白家族，该家族的蛋白包含有NBS 结构域和LRR 结构基序，在植物抵御各种病原物的侵袭中发挥重要作用。从‘嘎啦’苹果中鉴定了一个NBS-LRR 类基因，命名为MdNBS-LRR1，（GenBank 登录号：JX126858）。该基因全长为3 116 bp，包含一个2 826 bp 的开放读码框，编码包含941 个氨基酸残基的蛋白质；其氨基酸序列含有典型的NBS-LRR类抗病基因所具有的NB-ARC 结构域。Blast 分析发现MdNBS-LRR1 与大豆NBS-LRR 类抗性蛋白具有较高的氨基酸序列一致性（60%）。RT-PCR 分析结果表明，MdNBS-LRR1 在‘嘎啦’苹果的幼叶、茎、功能叶、芽、皮和花等组织中均有表达，在幼叶中的表达量最高，茎中最低。苹果轮纹病病原菌侵染可促进MdNBS-LRR1 基因表达上调，接种后24 d 表达量最高，是对照的10.6 倍左右，另外，在‘嘎啦’苹果幼苗叶片中，SA、MeJA 和ACC 均可诱导该基因的表达，表明MdNBS-LRR1 基因的表达受到与抗病相关信号转导途径的调控。

Identification of an Apple NBS-LRR1 Gene and Its Expression Analysis

NBS-LRR proteins are one protein family which contains Nucleotide-binding site（NBS）and leucine-rich repeat（LRR），and play an important role in defending plants from various pathogens. Anew NBS-LRR gene was identified from‘Gala’apple and named MdNBS-LRR1（JX126858）. The fullcDNA was 3 116 bp in length with an open reading frame（ORF）of 2 826 bp and encoded a protein of 941amino acids. The putative amino acid sequence contains an NB-ARC domain. The BLAST analysis exhibited high identity（60%）to NBS-LRR resistant protein（ACM89637）from Glycine max. Real time quantitative PCR analysis showed that the expression of MdNBS-LRR1 was observed in all tissues tested here including young leaves，shoot，functional leaves，bud，bark and flower，and the highest expression level was found in younger leaves. The expression of MdNBS-LRR1 was up-regulated by infection with Botryosphaeria dothide and reached the peak value at 24 d（10.6-fold higher than that in control）after inoculation. In addition，SA，MeJA and ACC could induce the expression of MdNBS-LRR1 gene in leaves，indicating that MdNBS-LRR1 could be regulated by the disease-resistant related signaling pathway.