Abstract: Using high temperature and HYP as direct and indirect selection stress, in vitro selection of heat-tolerant clonal lines from tussock plantlets and callus of senecio cruentus was carried out. The results showed that： ⑴ 40℃ for 16-20 h and 30 mmol·L^-1 HYP were optimal direct and indirect selection stress pressure, respectively; ⑵ Two heat- tolerant clones (Z_1-1-1 and N_1-2-1) were obtained by using high temperature direct selection , HYP and high temperature selection; ⑶ The regenerated plants of Z_1-1-1 were different significantly from their mother plants(Z₁) in leaf thickness, TPT/TST and stomata index. The fruit setting rate of adult plant of Z_1-1-1 was only 1.0% after artificial pollination , and the fruit setting rate of Z₁ was over 85%, ⑷ After heat stress(40℃ 24 h),the heat injury index, content of MDA and electrolyte leakage of the regenerated plants of Z_1-1-1 and N_1-2-1 were lower than their mother plants , but the activity of POD and SOD were higher than their mother plants (Z₁ and N₁).

Key words: Senecio × hybridus, Heat-tolerant clonal lines, In vitro selection, Heat stress