Assessment of Defense Responses in Resistant and Susceptible Cabbage Cultivars during Infection with Xanthomonas campestris pv. campestris

摘要

Eleven cabbage cultivars were assessed for their resistance to black rot caused by Xanthomonas campestris pv. campestris (Xcc). Of these, only one (Pusa Mukta) was resistant, six (Gaurav, Indam Saina, Indam Krishna, Unnati, NS 43 and NS 163) were moderately resistant, two (Quisto and Golden Acre) susceptible and two (NBH-Boss and Fl Bhima) highly susceptible. These cabbage cultivars were analysed for peroxidase (POX) activity and superoxide dismutase (SOD) activity. An increase in total POX and SOD activities were observed in all tested cultivars following inoculation with Xcc. The activity was greater in resistant cultivar than in susceptible ones. Reverse transcription -polymerase chain reaction (RT-PCR) confirmed the expression of these genes inresistant and susceptible cultivars. Both enzyme activity assays and RT-PCR analyses for the expression of the POX and SOD genes in susceptible and resistant cultivars demonstrated that the POX gene was up-regulated in resistant cultivar compared to susceptible cultivar. The results suggested that resistance in cabbage to Xcc infection was similar to a hypersensitive response (HR), although the onset of this response was delayed when compared to the occurrence of the classical HR.