火龙果茎溃疡病植株茎组织真菌群落特征分析

Characteristics of fungal community in stems of pitaya with canker disease

  • 摘要: 【目的】明确火龙果茎溃疡病对火龙果植株茎组织真菌群落的影响,为揭示火龙果溃疡病发生机制及防治技术研究提供理论依据。【方法】采集火龙果健康植株和溃疡病发病植株茎组织,利用Illumina高通量测序平台对植株茎组织真菌rDNA的ITS序列进行测序,分析健康植株与发病植株茎组织中的真菌群落特征差异。【结果】火龙果健康植株茎组织的真菌群落多样性显著高于发病植株(P<0.05,下同),且健康植株与发病植株茎组织的真菌群落组成具有明显差异。与健康植株相比,发病植株茎组织的子囊菌门(Ascomycota)和担子菌门(Basidiomycota)相对丰度较高,分别为49.11%和10.90%,门分类水平的未知真菌(unclassified_k_Fungi)的相对丰度较低(39.97%)。在属分类水平上,发病植株茎组织存在8个优势属,其中柱节孢属(Neoscytalidium)的相对丰度最高(33.29%),汉纳酵母属(Hannaella)、Dirkmeia、丛赤壳科未知属(unclassified_f_Nectriaceae)和刺盘孢属(Colletotrichum) 4个优势属的相对丰度显著高于健康植株,未在健康植株检测到柱节孢属、维希尼克氏酵母属(Vishniacozyma)和Meira;健康植株茎组织存在4个优势属,其中地霉属(Geotrichum)和链格孢属(Alternaria)的相对丰度显著高于发病植株。线性判别分析(LEfSe)结果显示,发病植株的柱节孢属和维希尼克氏酵母属以及健康植株的地霉属最能解释健康植株与发病植株间的差异。通过比对FUNGuild数据库预测真菌的营养型,发现发病植株中丰度最高的营养型为病理营养型(15.46%),健康植株中丰度最高的营养型是腐生营养型(7.95%)。【结论】火龙果发生茎溃疡病后其茎组织的真菌群落多样性显著下降,真菌群落结构发生改变。当病原营养型真菌显著富集在茎组织中时会破坏茎组织的菌群平衡,可能促进了茎溃疡病的发生。

     

    Abstract: 【Objective】 This study clarified the influence of canker on the fungal community in stem tissues of pitaya, to provide theoretical reference for the research on the occurrence and the prevention and control of pitaya canker.【Method】 The stem tissues of healthy and canker diseased plants of pitaya were collected, and the ITS sequences of rDNA of fungi in stem tissue were sequenced using Illumina high-throughput sequencing platform, so as to analyze the characteristics and differences of fungal communities in the stem tissues of healthy and diseased plants.【Result】 The diversity of fungal community in stem tissues of healthy plants was significantly higher than that of diseased plants(P<0.05, the same below), and the composition of fungal community in stem tissues of healthy plants was greatly different from that of diseased plants. Compared with healthy plants, the relative abundance of Ascomycota and Basidiomycota in stem tissues of diseased plants was higher, which were 49.11% and 10.90%, while that of unclassified_k__Fungi at the phylum level was lower(39.97%). At the genus level, there were 8 dominant genera in the stem tissue of the diseased plants. And the relative abundance of Neoscytalidium was the highest(33.29%). The relative abundance of 4 dominant genera, including Hannaella, Dirkmeia, unclassified_f__Nectriaceae, and Colletotrichum was significantly higher than that of the healthy plants, while Neoscytalidium, Vishniacozyma and Meira were not detected in healthy plants. There were 4 dominant genera in the stem tissues of healthy plants, of which the relative abundance of Geotrichum and Alternaria was significantly higher than that of diseased plants. The results of linear discriminant analysis effect size(LEfSe) showed that the difference between healthy and diseased plants could be best explained by Neoscytalidium and Vishniacozyma in diseased plants and Geotrichum in healthy plants. By analyzing the FUNGuild database to predict the trophic types of fungi, it was found that pathotroph(15.46%) contained the highest abundance in diseased plants, while saprotroph(7.95%) contained the highest abundance in healthy plants.【Conclusion】 When the pitaya canker occurred, the diversity of fungal community decreased significantly, and the composition of fungal community changed. When fungi of the pathotroph enriched significantly in stem tissues, the balance of the fungal community would be disturbed and probably trigger stem canker.

     

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