BROCCOLI PLANTS OVER-EXPRESSING A CYTOSOLIC ASCORBATE PEROXIDASE GENE INCREASE RESISTANCE TO DOWNY MILDEW AND HEAT STRESS

M. Jiang, J.J. Jiang, C.M. He, M. Guan

Abstract


Ascorbate peroxidase (APX) plays an important role in scavenging excessive reactive oxygen species (ROS) produced under environmental stresses, thus protects plant cells from oxidative injury. Seven Brassica oleracea var. italica (broccoli) lines over-expressing BoAPX gene were obtained using Agrobacterium tumefaciens transformation methods. The BoAPX over-expression plants exhibited significant higher resistance to Hyaloperonospora parasitica infection and heat stress as compared to the wild type broccoli. Among them, four gene over-expression lines, oe-apx07, oe-apx15, oe-apx32 and oe-apx33, demonstrated extremely higher enhanced tolerance to downy mildew. In addition, when treated with either H. parasitica or high temperature, lower level of relative electrical conductivity and higher level of APX enzyme activity were both observed in the oe-apx lines. These results indicated that over-expression of BoAPX gene contributes enhanced tolerance to both downy mildew and heat stress, and BoAPX gene plays an essential role in cellular defense against ROS-mediated oxidative damage in broccoli.

Keywords


Brassica oleracea var. italica; ascorbate peroxidase; APX; downy mildew; heat stress; over-expression

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DOI: http://dx.doi.org/10.4454/JPP.V98I3.018

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EDIZIONI ETS, Pisa, Italy