以印度梨形孢菌進行生物健化對草莓組織培養苗生長及其抗炭疽病能力之影響

Effects of biohardening with Serendipita indica on strawberry growth and resistance to Colletotrichum gloeosporioides

在臺灣，草莓炭疽病好發於育苗期和定植初期，已成為草莓產業重大威脅之一，前人研究顯示，本田期炭疽病發病嚴重與種苗潛伏感染有高度關聯性。以健化後之組織培養苗作為母株進行育苗或直接作為種苗，應可作為培育不帶炭疽病菌種苗的策略之一；然而健化時間長及價格較高等因素，除了部分專業苗園，一般農民使用組織培養苗的意願不高。本研究利用印度梨形孢菌（Serendipita indica）接種桃園一號（豐香）草莓組織培養苗，結果顯示隨著根系浸泡接種時間越長，印度梨形孢菌殖據率越高。將組織培養苗根系浸泡接種印度梨形孢菌一天及三天後，移植到介質中栽培至第八週時，除了植株的生物量（biomass）較對照組為高外，植株壯苗指數（seedling vigor index）亦高於對照組（但統計上無顯著差異）。此外，接種印度梨形孢菌一個月後的草莓組織培養苗，以炭疽病菌（1x 104 spores/mL）進行接種，發病程度顯著低於未經印度梨形孢菌處理之對照組。綜言之，接種印度梨形孢菌兼具促進臺灣主要草莓品種桃園一號組織培養苗生長及對炭疽病之抗性，達成生物健化（biohardening）之功能，未來應可將此概念及技術導入商業化草莓組織培養苗育苗過程，作為健康種苗來源的另一選擇。

"In Taiwan, anthracnose of strawberry, occurring mostly in the nursery and early transplanting stages, has become a big threat to strawberry industry. Previous studies revealed strong correlation between severe incidence of strawberry anthracnose in the field and quiescent infection of the seedlings. Therefore, utilization of the acclimatized micropropagated strawberry plantlets as parents or seedlings should be one of the strategies to produce disease-free seedlings. However, except in the professional nurseries, farmers usually do not have strong will to accept micropropagated strawberry seedlings due to their long acclimatization period and high cost. In this study, biohardening of micropropagated strawberry cv. Taoyuan No.1 (also known as “Fengxiang”) with Serendipita indica was carried out. The results showed that the longer the roots were soaked in the spore suspension of S. indica, the higher colonization rate was detected. Compared to the control group, inoculation of S. indica by root soaking for 1 and 3 days can increase the biomass of tissue culture seedlings and these treatments resulted in higher seedling vigor index among all the groups. After biohardening for one month, the acclimatized seedlings were inoculated with 1x104 spores/mL of Colletotrichum gloeosporioides. As a result, significant lower disease severity can be observed in S. indica-treated plants compared to the water-treated control plants. In conclusion, biohardening with S. indica can not only increase biomass of micropropagated strawberry cv. Taoyuan No. 1, but also enhance its tolerance to anthracnose of strawberry. In the future, the concept and technology of biohardening of micropropagated strawberry plantlets could be introduced into the seedling production system as an alternative means for providing disease-free strawberry seedlings."