Some species of Agave are highly endangered due to overexploitation and highly inefficient propagation systems. Consequently, an objective of this study was the establishment of reliable in vitro protocols for Agave propagation. In order to obtain a consistent micropropagation system for A. tequilana, 2,4-D-temporary pulses (exposure of explants for 1, 3 or 6 days) with concentrations of 2.3, 4.5, 6.8 and 9.0 mM were applied to apical shoot explants. For in vitro propagation of A. salmiana subspecies crassispina, A. duranguensis, A. oscura, A. pigmaea and A. victoria-reginae, a range of IBA levels (0.049, 0.49 and 2.46 lM) in combination with BA concentrations (0.44, 2.22, 4.44, 13.31 and 26.63 lM) were tested. After 60 days of culture, 12 axillary shoots per explant were obtained when Agave tequilana tissues were treated with 6.8 mM 2,4-D for 3 days. The most axillary shoots per explant were induced on several Agave species using IBA/BA treatments as follows: 3 for A. salmiana subspecies crassispina with 0.49/ 4.44 lM, almost 6 (5.9) for A. duranguensis with 0.049/4.44 lM, ca. 13 (12.8) for A. oscura with 2.46/ 4.44 lM, approximately 6 (5.6) for A. pigmaea with 0.49/13.31 lM and ca. 6 (5.5) for Agave victoriareginae with 2.46/2.22 lM. Although axillary shoot production by different Agave species varied depending on the IBA to BA ratio, low concentrations of these growth regulators improved shoot production compared to those reported in other studies.

Presence of potyvirus in single garlic (Allium sativum L.) cloves from the same bulb, and in five single leaves excised from commercial fieldgrown individual plants was studied using ELISA. It was found that the viruses were not present in all organs of the same plant, since some cloves of the same bulb were infected with potyvirus but some others were potyvirus-free. Analyzed leaves from a given plant also exhibited irregular distribution of potyvirus. This study also aimed to obtain potyvirusfree plants from two commercial garlic cultivars (Taiwan and Chileno) using cloves subjected to thermotherapy, chemotherapy or meristematic dissection followed by in vitro culture. Thermotherapy (sequential treatment at 32°C for a week, 36°C for 2 weeks, and 38°C for 3 weeks) was found to affect survival of explants and 36.5% cloves from Taiwan and 26.8% from Chileno cultivars were recovered after the treatment. ELISA tests showed that 63% of the cloves of Taiwan that survived the treatment and 70.9% of Chileno explants were potyvirus-negative. Regarding chemotherapy (205 lM Ribavirin solution), the explants (cloves) survived, but only an average of 27.0-34.8% were negative for the presence of potyvirus. When meristematic dissection was applied, an average of 41.7% explants of Taiwan and 34.2% of Chileno survived the treatment, and approximately 64% of these explants from both cultivars were potyvirus-negative. Potyvirus-free garlic plants grown in field conditions showed longer stems with a major fresh and dry weight per bulb, and also exhibited a higher yield than non-treated plants.

Mammillaria species are the most numerous within Cactaceae family, and some of them are threatened with extinction as a result of human activities. In this work, results of in vitro propagation are presented for ten Mammillaria species, testing 20 combinations of indole-3-acetic acid (IAA) and kinetin. Best results on shoot formation were obtained using kinetin at two levels: 27.9 and 46.5 μM. All IAA levels tested were able to induce de novo shoot formation in M. bocasana, M. densispina, M. hahniana, M. hutchisoniana, M. orcutii, M. pectinifera, M. perbella, M. picta, M. rhodantha, and M. zephyranthoides.Depending on the IAA level tested, four responding groups were observed concerning their highest shoot-formation number. For all species, the highest average of shoot formation was achieved with 5.7:46.5 or 11.4:46.5 μM IAA/kinetin, yielding 4.8 and 4.7 shoots per explant, respectively, in 60 d. Rooting of regenerated shoots was achieved by leaving the explants in their shoot-induction medium or transferring them to half-strength MS medium. Hardening of regenerated plants was successfully achieved by planting them in peat moss substrate after a desiccation treatment at room temperature for 3 d.

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