不同生态型天麻块茎腐烂病抗性差异分析

Resistance of different ecotypes of Gastrodia elata to tuber rot

随着天麻的规模化种植,块茎腐烂病已成为影响天麻生产的突出问题。该文在天麻病害调查基础上,通过大田试验比较不同生态型天麻对块茎腐烂病的抗性,结合组织学和转录组学分析,揭示不同生态型天麻抗病性差异及其原因。结果显示,乌天麻块茎腐烂病发病率较高,绿天麻次之,红天麻和乌红杂交天麻发病率最低,块茎腐烂病的发生表现出明显的植物基原特异性;天麻病害主要发生在芽部及底部,病菌侵染天麻后,菌丝在皮层细胞传播扩散,可改变天麻皮层及薄壁组织中的内生真菌结构。与红天麻相比,乌天麻复合表皮下的溶菌层较薄,薄壁细胞中有较多的多糖块状物;组学分析结果发现,乌天麻在免疫防御、酶类合成、多糖合成、碳水化合物运输及代谢、羟化酶活性、芳香类化合物合成等相关基因的转录表达上均与红天麻存在显著差异。分析结果表明,不同生态型天麻对块茎腐烂病的抗性差异可能与其基因表达模式及次生代谢物质的差异性有关,这些发现为天麻块茎腐烂病害防控及种植技术提升提供基础数据。

Tuber rot has become a serious problem in the large-scale cultivation of Gastrodia elata. In this study, we compared the resistance of different ecotypes of G. elata to tuber rot by field experiments on the basis of the investigation of G. elata diseases. The histological observation and transcriptome analysis were conducted to reveal the resistance differences and the underlying mechanisms among different ecotypes. In the field, G. elata f. glauca had the highest incidence of tuber rot, followed by G. elata f. viridis, and G. elata f. elata and G. elata f. glauca×G. elata f. elata showed the lowest incidence. Tuber rot showcased obvious plant source specificity and mainly occurred in the buds and bottom of G. elata plants. After infection, the pathogen spread hyphae in host cortex cells, which can change the endophytic fungal community structure in the cortex and parenchyma of G. elata. G. elata f. glauca had thinner lytic layer and more sugar lumps in the parenchyma than G. elata f. elata. The transcription of genes involved in immune defense, enzyme synthesis, polysaccharide synthesis, carbohydrate transport and metabolism, hydroxylase activity, and aromatic compound synthesis had significant differences between G. elata f. glauca and G. elata f. elata. These findings suggested that the differences in resis-tance to tuber rot among different ecotypes of G. elata may be related to the varied gene expression patterns and secondary metabolites. This study provides basic data for the prevention and control of tuber rot and the improvement of planting technology for G. elata.