紅龍果濕腐病菌Gilbertella persicaria之生物特性與發病條件之探討
Other Title
Biological Characteristics and Pathogenicity of Pitaya Isolates of Gilbertella persicaria
Journal
台灣農業研究
Journal Volume
74
Journal Issue
4
Start Page
497
End Page
513
ISSN
2790-086X
Date Issued
2025-12-08
Author(s)
Abstract
由 Gilbertella persicaria 引起的紅龍果濕腐病是影響臺灣紅龍果產業的重要病害之一，然而其菌株之生物特性與致病性尚未完全釐清。自 2009–2024 年，本研究於全臺 11 個縣市、23 鄉鎮，共 90 處之田間與 1 處市場，採集罹病紅龍果樣本，分離得 212 株 G. persicaria，全部都為負交配型。此外，亦自田間與市場之罹病草莓與桃子，各分離得 1 株 G. persicaria，皆為正交配型，顯示 G. persicaria 在臺灣同時存在有 2 種交配型。為探討G. persicaria不同寄主來源菌株之差異，進一步進行形態學、病原性及分子親緣關係分析。結果顯示 (1) 形態方面，紅龍果分離株孢囊壁片數平均值顯著高出模式菌株 (type strain) 2.1–2.6 片；(2) 病原性測試顯示，僅紅龍果分離株才能在紅龍果果實上引起典型的濕腐病病徵，且病徵形態與病斑大小及 G. persicaria 寄主來源有關，而與交配型無關；(3) 利用內轉錄間隔區 (internal transcribed spacer; ITS)、actin 及 28S rDNA large subunit 等 3 個 DNA 片段的序列建構之親緣關係樹分析結果顯示，紅龍果分離株可獨自成為一支序群。由形態、病原性及親緣關係來看，紅龍果分離株具有獨特性。在發病條件試驗中，最適發病溫度為 28–36℃，最適發病相對濕度 (relative humidity; RH) 為 80% 以上，16℃以下或 40℃以上則不發病。進一步於田間將不同齡期果實接種 G. persicaria，並於成熟採收後貯放於 25–32℃環境中以觀察病害發展情形。結果發現以採收後接種之果實其發病率與罹病度最高，顯示該菌之主要感染時期為果實成熟階段，特別是在採收時期。
Wet rot of pitaya, caused by Gilbertella persicaria, is a significant disease affecting pitaya production in Taiwan. However, the biological characteristics and pathogenicity of the pathogen remain unknown. From 2009 to 2024, diseased pitaya tissues showing symptoms of wet rot were collected from 90 field sites across 23 townships in 11 counties, as well as from one local market in Taiwan. A total of 212 isolates of G. persicaria were obtained from pitaya, all of which belonged to the minus (-) mating type. Additionally, one isolate of G. persicaria from a diseased strawberry and another from a peach were both identified as the plus (+) mating type. These results indicate that both mating types of G. persicaria are present in Taiwan. To further investigate host-related differences among G. persicaria isolates, morphological, pathogenicity, and molecular phylogenetic analyses were conducted. The results showed that: (1) Morphologically, the number of sporangial wall segments in pitaya isolates was significantly higher than that of the type strain, by an average of 2.1–2.6 segments; (2) In pathogenicity assays, only pitaya isolates were able to induce typical wet rot symptoms on pitaya fruits. The results indicated that symptom type and lesion size were associated with the host origin of G. persicaria isolates, but not with their mating type; (3) In phylogenetic analysis, the phylogenetic tree based on concatenated sequences of internal transcribed spacer (ITS), actin, and 28S rDNA large subunit revealed that pitaya isolates formed a distinct monophyletic clade. Based on morphology, pathogenicity, and phylogenetic analyses, the pitaya isolates of G. persicaria were different from the type strain. Environmental condition assays indicated that optimal temperature and relative humidity range for disease development are 28–36℃ and above 80%. No disease symptoms developed at temperatures below 16℃ or above 40℃. Further inoculation trials were conducted on pitaya fruits at various developmental stages, followed by postharvest incubation at 25–32℃ to observe disease progression. These results demonstrated that fruits exhibited the most severe disease by postharvest inoculation, indicating that G. persicaria primarily infects pitaya during the fruit maturation stage, particularly at harvest.
Subjects
孢囊壁分裂數
交配型
病原性
親緣關係
感染時機
Sporangial wall segment
Mating type
Pathogenicity
Phylogeny
Infection timing
Publisher
農業部農業試驗所
Type
journal article
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