Abstract:

The aim was to study the relationship between the phenol metabolism and the resistance to Ceratocystis fimbriata Ellis et Halsted in sweet potato, and provide the resistant indices for identification and selection of C. fimbriata Ellis et Halsted. ‘Nanjing-92’ (High resistance) and ‘Yantai-252’ (High infection) were chose as material. The inoculating experiment on the disease fungi of the resistant and sensitive varieties was conducted to study the effects of C. fimbriata Ellis et Halsted on chlorogenic acid and total phenol content, PPO and PAL activity. The PLA activity of high resistant variety increased rapidly (one day later) and maintained higher lever in the next few days after it had been infected by C. fimbriata Ellis et Halsted. The PLA activity of high susceptible variety increased significant (three days later) and decreased rapidly (five days later) after it had been infected by C. fimbriata Ellis et Halsted. The chlorogenic acid content of two varieties increased rapidly after there had been infected by C. fimbriata Ellis et Halsted. However the chlorogenic acid content of high resistant variety was 56.6%-327% higher than that of high susceptible variety. The PPO activity and total phenol content of high resistant variety increased rapidly and the relay time was longer than that of high susceptible variety after there had been infected by C. fimbriata Ellis et Halsted. The resistance of sweet potato to C. fimbriata Ellis et Halsted would be increased with the increase of PLA activity, chlorogenic acid content, PPO activity and total polyphenol content.