Abstract:

To study the mechanism of aphid resistance in tobacco varieties, six tobacco varieties with different aphid resistance were selected and inoculated with aphid in pot experiment. The content change of jasmine acid (JA) and nitric oxide (NO), and CAT activities in tobacco leaves were determined 0, 3, 6 and 9 hours after feeding aphid. The results showed that: after being infested by aphids, the JA content in tobacco leaves increased first, peaked at 6 hours and then decreased. The increment of JA content in resistant varieties was higher than that in susceptible varieties. The NO content in leaves of aphid resistant varieties increased first, peaked at 3 hours and then decreased. The difference of the NO content in leaves of susceptible varieties was not significant between 3 hours’ aphid feeding and 0 h, but decreased significantly after 6 hours and 9 hours. The CAT activity of all tested tobacco varieties showed an increasing trend at 9 h, and CAT activity of aphid resistant variety ‘Shubalaomuji2113’ increased the most. Therefore, JA and NO contents and CAT activity could be used as physiological indicators for aphid resistance identification in tobacco varieties. The increase of JA content in leaves 5-6 hours after inoculation could be used to identify the resistance of tobacco varieties to aphids.

Key words: Myzus persicae, tobacco variety, defensive enzyme, signal molecules, aphid resistance