大蒜气生鳞茎脱毒快繁

Rapid propagation of virus-free garlic aerial bulbs

长期的无性繁殖使大蒜(Allium sativum)产业发展面临病毒积累和繁殖系数低等严峻问题,而大蒜离体微繁技术能有效解决上述问题。气生鳞茎是离体诱导脱毒苗的首选材料,但其具有休眠特性,因此高效人工破眠技术是彻底解决这些问题的基础。本研究以蒜薹为外植体诱导形成气生鳞茎,通过物理及生长调节剂的方法打破气生鳞茎休眠,然后以气生鳞茎为外植体直接诱导试管苗,并对气生鳞茎试管苗的脱毒效果进行检测。结果表明,以长度为15 cm的带花苞蒜薹为外植体诱导形成气生鳞茎,最适培养基为液体MS+(0.20.3 mg·L-1)萘乙酸(NAA)+(0.30.5 mg·L-1) 6-苄氨基腺嘌呤(6-BA),气生鳞茎诱导率可达100%,且数量高达147粒;通过比较机械伤害、低温(4°C)、赤霉素(GA3)、乙烯(ETH)等几种不同方式打破气生鳞茎休眠的效果,得出最佳破眠方式为低温14 d+100 mg·L-1GA3+20μL·L-1 ETH,处理后20 d气生鳞茎的萌芽率可达50%;气生鳞茎试管苗可完全脱除大蒜普通潜隐病毒(GarCLV),对洋葱黄矮病毒(OYDV)的脱除率可达94.87%,脱毒苗叶片组织细胞排列紧密且规则。

Serious problems such as garlic virus accumulation and a low reproductive coefficientstemming from long-term asexual reproduction in the garlic industry, can be effectively overcome using in vitro micropropagation technology. Garlic aerial bulbs are the optimum material for in vitro-induced virus-free seedlings but have dormancy characteristics. Therefore, efficient artificial dormancy-breaking technology is the basis to solve these problems thoroughly. In this study, garlic scapes were used as explants to induce aerial bulbs, whose dormancy was then broken using physical and growth regulators. The aerial bulbs were subsequently used as explants to directly induce plantlets, which were then tested for the presence of viruses. The optimum induction of aerial bulbs was obtained from 15-cm-long scapes bearing flower buds, and the best induction medium was liquid Murashige–Skoog(MS) medium containing 1-naphthylacetic acid(NAA)(0.2–0.3 mg·L-1) and 6-benzylaminopurine(6-BA)(0.3–0.5 mg·L-1). The rate of aerial bulbs induction was 100%, with up to 147 aerial bulbs generated per scape. The optimum treatment for aerial bulb dormancy break, which was determined by comparing the effects of mechanical injury, low temperature(4°C), and treatment with gibberellin(GA3) and ethylene(ETH), was low temperature for 14 days followed by application of 100 mg·L-1 GA3+20 μL·L-1 ETH. After 20 days of treatment, the aerial bulb germination rate was as high as 50%. Garlic common latent virus(Gar CLV) was completely absent from the aerial bulb-induced plantlets, and up to 94.87% of Onion yellow dwarf virus(OYDV) was removed using this approach. Leaf tissue cells of the virus-free plantlets were tightly and regularly arranged.