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Abstract

Purpose: The study aimed to investigate cold tolerance of the dongnongdongmai 1 (‘dn1’), and the influence of exogenous ABA on this tolerance. Methods: At three-leaf stage, leaves were sprayed with 1×10﹣5 mol/L ABA, 5×10﹣3mol/L sodium tungstate and clean water, respectively. The dosage was 1L/row, and each treatment repeated 5 times. Leaves and rhizomes were collected at 0°C, -10°C, -20°C and -25°C, respectively. Contents of H2O2 and antioxidants (AsA, GSH, AsA+DHA and GSH/GSSG); activities of SOD, POD, CAT, APX, GR, DHAR and MDHAR; and AsA-GSH cycle-related gene expressions were determined at each temperature. Results: In leaf, cold stress significantly increased H2O2 and relative conductivity; while, ABA had a significantly reduced effect. Antioxidant enzymes activities, contents of antioxidants, AsA-GSH cycle-related enzyme activities and gene expressions showed an increasing-decreasing trend under cold stress; while ABA had a significantly increased effect, and even made the peak values of antioxidants contents move to a lower temperature (from -10 to -20°C). In rhizome, change trends of APX activity and TaAPX expression kept stable from 0 to -20°C. The peak value of AsA and GSH contents moved to a lower temperature than in leaf (-20°C vs -10°C). ABA had a similar effect as in leaf, except that the peak value of APX activity and TaAPX expression were at a lower temperature (-20°C vs -10°C). Conclusions: In the ‘dn1’, rhizome had a higher cold tolerance than leaf. Exogenous ABA could enhance the cold tolerance in both leaf and rhizome, even under severe cold stress.

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