Effect of Pratylenchus zeae infection on the expression of isozyme activities in resistant and susceptible sugarcane clones

Abstract

AbstractThe constitutive levels of both phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) activities in roots and leaves were found to be greater in sugarcane clones resistant to the lesion nematode Pratylenchus zeae than in susceptible clones. Investigations on the sequential development of PAL and TAL activities were undertaken in resistant (Co 7717) and susceptible (CoC 671) sugarcane clones infected with P. zeae. PAL activity in both roots and leaves of the resistant clone showed a maximum percentage increase, compared with non-infected controls, at 35 and 14 days after infection (DAI), respectively. However, in the susceptible clone the maximum percentage decrease compared with the non-infected clone was observed at 3 and 14 DAI. TAL activity in the resistant clone showed the maximum percentage increase compared with the non-infected control at 28 DAI in roots and 7 DAI in leaves, whereas in the susceptible clone the maximum percentage decrease compared with the non-infected control was at 35 DAI in roots and 28 DAI in leaves. In experiments on the induction of enzyme response to infection by P. zeae, eight resistant and eight susceptible clones were analysed 14 days after P. zeae infection. Among the eight resistant clones six showed increased PAL activity compared with non-infected clones. Four susceptible infected clones showed a decrease as compared with non-infected clones, while the remaining four infected clones showed an increased enzyme activity compared to non-infected clones. Superoxide dismutase (SOD) activity increased quantitatively in both roots and leaves from nematode-infected susceptible clones compared to non-infected clones. The SOD activity decreased in roots and leaves from nematode infected resistant clones, when compared to the non-infected-resistant clones. In native PAGE analysis of SOD and esterase activities the major differences between infected and non-infected clones of resistant and susceptible sugarcane were observed in low and medium electrophoretic mobility ranges.