Methyl jasmonate regulates protective enzyme activities to improve resistance to Venturia nashicola in pear (Pyrus bretschneideri Rehd.)

Abstract

Pear scab caused by Venturia nashicola is a devastating disease responsible for huge economic losses to the pear industry. The enhancement of pear resistance to scab by methyl jasmonate (MeJA) was evaluated in the susceptible cultivar ‘Xuehua’ and the resistant cultivar ‘Huangguan’ of Chinese pear (Pyrus bretschneideri Rehd.). The regulatory mechanism of MeJA was analyzed by measuring the activities of four protective enzymes and expression levels of corresponding genes. The results showed that MeJA inhibited the growth of V. nashicola on oat agar medium. The in vitro growth-inhibitory effect of MeJA was enhanced with increasing MeJA concentration over the range 0.05–2 mmol L− 1, and the difference was significant at 0.1 mmol L− 1 or higher concentration levels (p < 0.05). Except peroxidase, all the other enzymes exhibited higher activities in ‘Huangguan’ pear than in ‘Xuehua’ pear after inoculation. Treatment with 0.1 mmol L− 1 MeJA substantially enhanced all the protective enzyme activities in inoculated leaves of the two pear cultivars, with increased expression of related genes. These results indicate that MeJA improves resistance of pear to scab by increasing protective enzyme activities.