Virus Free Garlic (Allium Sativum L.) Plants Obtained by Thermotherapy and Meristem Tip Culture

Abstract

Virus infection in garlic considerably reduces yield and quality in Argentina. The production of virus free “seed” was attempted by means of thermotherapy and meristem tip culture. A hot water treatment was employed to determine the lethal temperature/time combination for clonal type (c.t.) Blanco cloves. It was established that 50°C × 20 min, 50°C × 15 min and 55°C × 5 min were the limit thermal/time combinations which garlic could withstand. Those treatments were employed followed by meristem tip culture, however, none of the successfully developed plants after culture (only 13 %) were virus‐free. Hot air treatments in a growth chamber at 36°C lasting for 30, 40 and 60 days, and at 25°–32° for 30 days in a greenhouse were tested on c.t. Blanco. Cloves kept at room temperature throughout the experiment were employed as controls. In the 25°–32°C treatment, 73% of meristems produced plants and, of these, 33 % were virus free. After 30 and 40 days at 36 °C, 62 % and 67 % of the meristems developed into plantlets, of which respectively 51 % and 50 % were virus‐free. Very few meristems (10 %) developed into plants when cloves had been kept at 36°C for 60 days but the resulting plantlets were all virus free. Controls produced 78 % of plants, of which 14 % were virus free. Results of hot air treatments of 36 °C for 40 days performed on c.t. Colorado, Rosado, Paraguayo, Espaol and Hilario Ascasubi were similar to those obtained with c.t. Blanco. In Espaol and Hilario Ascasubi, no virus‐free plants were detected among control specimens (no thermotherapy treatment). The only virus (from up to 3 that infected the plants) that persisted in some plants after themotherapy and meristem tip culture was garlic yellow streak.

Shoot tip culture and thermotherapy for recovering virus-free plants of garlic

“…(Aceito para publicação em 18 de setembro de 2.000) garlic cloves, obtained via shoot tip culture (Havránek, 1972(Havránek, , 1974Quit, 1972;Wang & Huang, 1974;Daniels, 1977;Conci et al, 1986;Walkey et al, 1987;Conci & Nome 1991;Verbeek et. al., 1995).…”

“…A polyvalent policlonal antiserum (Gama & Avila, 1988) was used for the tests which were also performed using specific policlonal antisera against the potyviruses Onion yellow dwarf virus (OYDV), Leek yellow stripe virus (LYSV), and the carlaviruses Carnation latent virus (CLV) and Shallot latent virus (SLV) (Conci & Nome, 1991).…”

Rapid Propagation of High-quality Garlic Seed-bulb Derived from Meristem-tips.

“…Symptom-less plants can be obtained through meristem -tip culture and the resultant plants have better yield and quality (Ogawa et al, 1976;Bhojwani, 1980;Mikami, 1984;Walkey et al 1987;Walkey and Antill,1989;Novak, 1990;Conci and Nome 1991). However, viruses were detected with high frequency from meristem -tip derived plants when virus indexing was assesed using antisera (Walkey et al, 1987;Conci and Nome, 1991). Thus, studies of conditions for meristem-tip culture are needed, as are adequate methods for indexing of garlic viruses.…”

Biotechnological Tools for Garlic Propagation and Improvement

“…For this purpose, it is recommended to isolate explants of maximum 5mm, although sometimes their size may limit their establishment in vitro. Meristem culture enabled virus-free plants to be produced in various regions in the world (Walkey, 1987;Bhojwani et al, 1982;Peña-Iglesias & Ayuso, 1982;Bertacinni et al, 1986;Conci & Nome, 1991). In Slovenia, Eastern Europe, a trial was conducted to eliminate the OYDV in plants of the cultivar Ptujksi-spomladanski through thermotherapy and meristem culture.…”