蔥屬（＂Allium＂）植物的病毒檢測與健康種蔥培育

洋蔥以外的蔥屬（Allium）植物多數行無性繁殖，青蔥雖可開花結籽，四季蔥的經濟栽培主要採用分株繁殖，因此在母株體內的病毒也隨無性繁殖體延續感染繼代子苗，在田間發展成類似品種退化的現象，影響蔥的品質與產量。在臺灣感染蔥屬植物的病毒種類計有大蒜蟎媒絲狀病毒（GarMbFV）、大蒜潛隱病毒（GarLV）、分蔥潛隱病毒（SLV）、洋蔥黃萎病毒（OYDV）、韭蔥黃條斑紋病毒（LYSV）、分蔥黃條斑紋病毒（SYSV）及菸草嵌紋病毒（TMV）等，其中感染青蔥的病毒有SLV、LYSV、SYSV及OYDV。利用ELISA檢測這些病毒，偽陽性結果的機率偏高，搜尋試用引子對Allex-CP/NABP、OYDV.VKB 3F/ OYDV.VKB 3R及LYSV WAF/ LYSV WAR並自行設計引子對SLV-DF1/ SLV-DR1，以反轉錄聚合酶鏈式反應（reverse transcription-polymerase chain reaction，RT-PCR）的結果來確認病毒檢驗結果。調查宜蘭縣三星鄉青蔥病毒發生情形，結果SLV發生較普遍，而其他種病毒較少發生，因此初步設定健康無特殊病原（SPF）蔥苗的標準即無SLV感染。培育健康種蔥有三種方式：1.篩選無病毒母株取分株苗、2.微體培養去除病毒後建立組培苗、3.種子播種取實生苗等，都可以避開種苗帶病毒的問題。利用無SLV感染的青蔥組培苗進行產量試驗，在株高、單株重及莖徑三方面都較SLV感染者高。從篩選無病毒的「大旺蔥」中以分株苗自行留種，經3代篩選繁殖，比一般未篩檢的苗所生產的青蔥產量高約28%。

"Most plants of Allium, except onion, are propagated with vegetative multiplication. Although blooming and seeding are common in Welsh onions, their economic cultivation mainly depend on tillers for division propagation. Therefore, the Welsh onion plants in the field are frequently infected by viruses and that causes the losses of quality and yield. The contagious viruses are readily transmitted from mother plants to the seedlings of next generation in which similar 'species degeneration' symptoms are appeared. Viruses infecting alliums, such as Garlic mite borne filamentous virus (GarMbFV), Garlic latent virus (GarLV), Shallot latent virus (SLV), Onion yellow dwarf virus (OYDV), Leek yellow stripe mosaic virus (LYSV), Shallot yellow stripe virus (SYSV) and Tobacco mosaic virus (TMV), in which SLV, LYSV, SYSV and OYDV have been documented to infect Welsh onions in Taiwan. Due to high probability of false-positive results from ELISA, three previously reported primers (Allex-CP (+) / Allex-NABP (-), OYDV.VKB 3F / OYDV.VKB 3R, and LYSV WA / LYSV WAR) and one newly designed primer pair (SLV-DF1 / SLV-DR1) were adopted for reverse transcription polymerase chain reaction (RT-PCR) to detect the viruses. A survey for Welsh onions infected by viruses in Sansing Township, Yilan County indicated that SLV was the most prevalent while LYSV, SYSV and OYDV were occurred rarely. Accordingly, the specific pathogen-free (SPF) standard for SLV-free healthy seedlings of Welsh onion has been set. Three ways are commonly performed to raise healthy seedlings of Welsh onions: 1. screening of virus-free plants and from which to obtain tillers for division multiplication, 2. elimination of viruses by micro propagation to obtain healthy plantlets, and 3. selection of normal true seedlings from seed-sown materials. The yield trial showed that the growth potentials of healthy plants were significantly greater than SLV infected ones in height, weight, and stem diameter of plants. Through reproduction of three generations from virus-free tillers for division multiplication, plants of Welsh onion cv. Dawan yield more about 28% than that of non-screening seedlings."