Piriformospora indica 對草莓組織培養苗健化、營養生長及抗生物性逆境之影響評估

Investigation of the effects of Piriformospora indica on biohardening, growth promotion and biotic stress tolerance of micropropagated strawberry

簡怡珍(Yi-Chen Chien)

指導教授 ： 林乃君

國立臺灣大學/生物資源暨農學院/植物醫學碩士學位學程/碩士(2017年)

https://doi.org/10.6342/NTU201703793

摘要

草莓為薔薇科草本植物，為一高經濟栽培作物，其栽培過程首重育苗，全台種苗每年需求量高達 2, 500 萬株。目前育苗方式多採以健康母株之走莖繁殖，育苗時期最大瓶頸則在於健康種苗的篩選及病害管理，據調查顯示本田期缺株的原因多為苗期入侵之病原菌潛伏感染所造成，主要為炭疽病 (Colletotrichum gloeosporioides) 與萎凋病 (Fusarium oxysporum f. sp. fragariae)，若育苗時期能有效降低潛伏感染機率，應可大幅減少田間發病的情形。為達此目的，除了使用健康母株進行育苗外，選用不帶菌之組織培養苗經健化後做為母株或種苗，也可提高獲得健康種苗的機率；但組織培養苗若未經良好的健化程序便直接栽種於田間，其生長勢及產果率均會較農民自行留種的走莖苗差，加上價格較高，因此目前農民的接受度頗低。印度梨型孢真菌 (Piriformospora indica) 是於印度發現的根部內共生菌，特性為宿主範圍廣，且已知對多種植物的生長發育有促進作用，不僅可增加植物生物量，也可以幫助宿主植物對抗各種逆境。因此本研究擬利用印度梨型孢真菌接種草莓組織培養苗來促進瓶苗的健化，提高其營養生長及對生物逆境之耐受性，冀望未來能為健康種苗之培育提供另一個良好的策略。結果顯示，瓶苗接種、根系浸泡接種及澆灌接種三種不同的接種方法，均是隨接種時間越長，根系中的 P. indica 共生率越高，其中又以根系浸泡接種 1 天及 3 天的接種方法和對照組比較，具有促進組織培養苗生物量之效果，植株壯苗指數亦以浸泡接種 1 天及 3 天的處理組顯著高於其他組別。草莓組織培養苗以浸泡接種 P. indica 3 天，並經過健化 1 個月後，接種 104 spores/mL 炭疽病孢子進行病原性試驗，P. indica 處理後的植株發病嚴重程度在接種後第 9 天即顯著低於對照組。然而接種106 spores/mL 萎凋病菌孢子 6 週後，處理 P. indica 的發病嚴重程度與對照組比較則無差異。綜言之，印度梨型孢真菌可以促進草莓組織培養苗的生長並增加其對炭疽病的抗性，但對草莓萎凋病的抗性則無幫助。

關鍵字

草莓 ； 印度梨型孢真菌 ； 組織培養苗 ； 生物健化 ； 生物逆境

並列摘要

Strawberry (Fragaria x ananassa Duchesne) is an economically important herbaceous plant belonging to family Rosaceae, and seedling production is usually the limiting factor during strawberry cultivation. In Taiwan, the annual seedling demand could be up to 25 million. Currently, strawberry seedlings are mainly propagated with runners (stolons) from healthy mother plants, and the biggest bottleneck is how to screen for healthy seedlings and disease management in the nurseries. According to the survey, the high replanting rate in the field is mainly due to latent infection of seedings by Colletotrichum gloeosporioides and Fusarium oxysporum f. sp. fragariae (Fof). If latent infection can be prevented effectively, disease severity in the field can be controlled better. In addition to propagating seedlings from healthy mother plants, raising seedlings from or directly utilizing micropropagated strawberry plants should increase opportunities to obtain healthy seedlings. However, transplantation of micropropagated seedlings without proper hardening procedures into the field usually leads to problems, such as poor growth and yield, and such seedlings are usually pricy, so the farmers dislike to use micropropagted seedlings. Piriformospora indica is a root endophytic fungus isolated in India with characteristics of wide host range and ability to promote plant growth and enhance plant tolerance to various stresses. In this study, I attempted to promote strawberry growth and tolerance to biotic stresses by biohardening of micropropagated strawberry with P. indica. Hopefully, an alternative mean for cultivation of healthy seedlings could be provided in the future. The results showed that no matter media, root soaking or drenching inoculation method was used, the longer the treatment, the higher the inoculation and the root colonization rates. Compared to the control group, inoculation of P. indica by root soaking for 1 and 3 days can increase the biomass of tissue culture seedlings and these treatments resulted in the highest seedling vigor index among all the groups. After root soaking in 1×105 spores/mL P. indica for 3 days and biohardening for one month, the strawberry seedlings were inoculated with 104 spores/mL C. gloeosporioides. Significant lower disease severity can be observed in P. indica-treated plants compared to the water-treated control 9 days after pathogen inoculation. Inoculation of 106 spores/mL Fof, disease severity of the P. indica-treated group was similar to the control group. In conclusion, P. indica treatment can increase biomass of micropropagated strawberry and its tolerance to anthranose but not Fusarium wilt of strawberry.

並列關鍵字

Strawberry ； Piriformospora indica ； micropropagated seedlings ； biohardening ； biotic stress

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