Elimination of Potyviruses from Two Commercial Iranian Garlic (Allium sativum L.) Populations through Thermotherapy and by Meristem Tip Culture

Elimination of Potyviruses from two commercial Iranian garlic populations, Hamedan and Azar-shahr, through thermotherapy and by meristem tip culture were investigated. The infected bulbs of either one of the populations were initially treated at 30o C for one week and then at 36oC for 5 weeks. The meristems of cloves at two sizes of 0.4-0.6 mm and 0.6-0.8 mm were then cultured on MS medium supplemented with NAA and BA. Following the growth of explants, ELISA test was performed to detect infection to potyviruses. The elimination rate of potyviruses in explants that were produced from small size meristem cultures was higher than in those produced from the bigger ones, obtained as 100% and 91% for meristem cultures of 0.4-0.6 mm, and 0.6-0.8 mm in size, respectively. In samples with mere thermotherapy and without any meristem tip culture, elimination rates were 73% and 61% for Hamedan and Azar-shahr populations respectively. Control plants (non-treated) showed than 80% infection rate. Growth regulator, NAA at a concentration of 0.1 mg/l, exerted a significant positive effect on proliferation, growth of plantlets and on the number of leaves. BA at concentrations of 0.1 and 0.5 mg/l significantly and positively affected proliferation and the number of leaves. Interaction of cultivars and meristem size had significant positive effects on only plantlet length. Treatment S2C1 bore the highest plantlet length.