Abstract:

Two vegetable soybean cultivars, Huning 95-1 (cold-tolerant cultivar) and Taiwan 75 (cold-sensitive cultivar) were used to investigate the effects of chilling stress on plant growth, metabolism of reactive oxygen species (ROS) and polyamines. The results showed that chilling stress significantly reduced the biomass production of both cultivars, with the reduction in Taiwan 75 more significant. When exposed to chilling stress, antioxidant enzymes activities, O·-2 producing rate, contents of hydrogen peroxide (H2O2) and malondiadehyde (MDA) increased significantly in both cultivars, with the fold of increment of antioxidant enzymes activities more significant in Huning 95-1 and O·-2production rate, contents of H2O2 and MDA in Taiwan 75, respectively. In addition, after chilling stress, contents of different forms of putrescine (Put), spermidine (Spd) and spermine (Spm) in leaves of Huning 95-1 increased significantly, contents of different forms of Put in leaves of Taiwan 75 decreased obviously, levels of free and conjugated Spd and Spm increased markedly, no significant difference was observed in bound Spd and Spm. These results indicated that different forms of Put, bound Spd and Spm were involved in lower growth reduction, lower oxidative damage and higher antioxidant enzymes activities in Huning 95-1, and they might play important roles in cold tolerance of vegetable soybean plants．

Key words: vegetable soybean, chilling stress, reactive oxygen species, polyamines