Abstract The regulation and the relationship of PPO actvity phenol contents and browning ratio in vitro of Comgxili (Pyrus pyrifolia Nakoi) and Jin hua (P bretshneideri Rehd) explants were studied.

• 梨外植体组织培养无病毒苗木是目前栽培苗木的主要来源，但是在培养过程中常由于褐变严重而造成材料溃烂，使组培成活率低。