甘蔗抗黄锈病G1标记的分子检测及候选抗病基因WAK的分析

甘蔗黄锈病是屈恩柄锈菌(Puccinia kuehnii Butler)引起的一种世界性真菌病害,导致产量减少和糖分降低,给甘蔗产业造成严重损失。本研究采用抗黄锈病分子标记G1,检测我国和世界上重要的甘蔗栽培品种、野生种和近缘属的抗黄锈病基因,并对扩增的代表性特异条带进行克隆测序、功能注释和聚类分析,推测其抗性基因的起源和进化。G1检测结果表明,国内124份甘蔗栽培品种检测到G1标记的有83份,占66.9%;国外46份甘蔗栽培品种检测到G1标记的有31份,占67.4%。34份甘蔗野生种和近缘属中检测到G1标记的有17份,占50%,其中割手密种含有该基因比例最高,为100%。功能注释揭示,G1标记的候选基因编码一种细胞壁连接的类受体激酶,并在甘蔗栽培品种的单倍体蛋白组数据库中鉴定到3个相似度较高的蛋白,这些蛋白都有细胞壁受体激酶结构的胞外域、跨膜域和激酶活性的胞内域。聚类结果则清晰展示了抗病候选基因的起源及进化关系,具体可分为3组,第1组来源于割手密种和大茎野生种;第2组来源于大茎野生种、热带种和河八王属;第3组来源于割手密种、大茎野生种、中国种和栽培品种。研究结果为抗黄锈病甘蔗品种的选育提供重要的抗源支撑,并为抗性分子机制的解析奠定基础。

Molecular detection of G1 marker for orange rust resistance and analysis of candidate resistance WAK gene in sugarcane

Sugarcane orange rust is an important fungal disease caused by Puccinia kuehnii Butler,which could lead to a reduction in sugarcane production and sugar content and cause serious losses to the sugarcane industry in worldwide.In this study,the molecular marker G1 was used to detect orange rust resistance genes in cultivars,ancestral species and the related genus of Saccharum in the world.The representative amplified bands were cloned,sequenced,functionally annotated,and clustered,and the origin and evolution of resistance genes was then analyzed.The results showed that 83 and 34 were detected with G1 marker,accounting for 66.9%and 67.4%in 124 Chinese and 46 foreign sugarcane cultivars,respectively.Among 34 sugarcane ancestral species and the related genus of Saccharum,17 were detected by G1 marker,accounting for 50%,of which the highest percentage(100%)was in Saccharum spontaneum.Functional annotation revealed that G1 target gene encoded a wall-associated receptor-like kinase(WAK),and three proteins with high similarity were identified from the haploid proteome database of sugarcane cultivars.These proteins all contain the extracellular domain,transmembrane domain and intracellular domain with kinase activity of typical cell wall receptor structures.Phylogenetic analysis of nucleotide sequences clearly showed the origin and evolution of the candidate resistance WAK genes.Specifically,the WAK genes amplified by G1 marker could be divided into three groups.The first group is from S.spontaneum and Saccharum robustum.The second group is from S.robustum,Saccharum officinarum and Narenga porphyrooma.The third group is from S.spontaneum,S.robustum,Saccharum sinense and cultivars.These results provided an important support for breeding of sugarcane cultivars resistant to orange rust,and lay a foundation for further analysis of molecular mechanism of resistance genes.