Abstract: The three-year old potted trees of Malus hupehensis（Pamp）Rehd. var. pinyiensis Jiang were irrigated with water solution of 2,4-D to investigate the characteristics of cell death and the expression of anti-apoptotic genes of new roots（extensive roots and absorbing roots）. The result showed that the new roots’ cell death quantity and caspase-like 3/7 activity increased first and then fell in the 70 days after the treatment of 60 mg · L^-1 2,4-D，however，the ATP content and the root activity changed in the contrary trend. After the treatment，the expression of anti-apoptotic genes MhHSP70，MhBI-1，MhBAG were induced and the expression levels of MhBAG first decreased then increased，however MhHSP70 and MhBI-1 increased first，and then decreased later. At the same time，the change range of cell death quantity and caspase-like 3/7 activity and the rising range of MhHSP70 and MhBI-1 expression levels in absorbing roots were greater than that in extensive roots in the early stage of the 2,4-D treatment，which showed that absorbing roots had higher sensitivity to 2,4-D than extensive roots. When at peak value，the expression levels rising times of anti-apoptotic genes in extensive roots were significantly higher than that in absorbing roots，which indicated that the extensive roots had stronger anti-apoptotic ability than absorbing roots.

Key words: Malus hupehensis（Pamp）Rehd. var. pinyiensis Jiang, 2,4-dichlorophenoxyacetic acid, extensive roots, absorbing roots, anti-apoptotic gene, cell death