Participation of Chitin-Binding Peroxidase Isoforms in the Wilt Pathogenesis of Cotton

Egor Pshenichnov,Alik Akhunov,Zamira Golubenko,Robert D Stipanovic,Nigora Khashimova

doi:10.4236/ajps.2011.21005

Abstract

Specific chitin-binding isozymes of peroxidase (POX) play an important role in pathogenesis of plant diseases caused by fungi. We studied the dynamics of peroxidase activity in two varieties of cotton (Gossypium hirsutum L.); one was susceptible and the other resistant to the plant pathogen Verticillium dahliae. After infection with strongly and weakly virulent isolate of V. dahliae, we observed a correlation between the level of seedling tissue lesion and peroxidase activity. Thus, the first POX activity was observed in all infected plants 2 hours after inoculation, but POX activity of the resistant variety rapidly increased and maximized 3 days after infection, while POX activity in the susceptible variety showed a slow increase that continued to increase during the remaining 8 days of experimental observation. The increase of POX activity in the susceptible variety after infection may be explained by progressive fungal colonization of cotton tissues leading to irreversible senescence. Microscopic examination of plant tissues supports this hypothesis. The more virulent isolate caused more necrosis and significantly more POX activity than the mildly virulent in both susceptible and resistant plants. Control plants showed no changes in POX activity; however, the POX activity in the control resistant varieties was higher than the control susceptible varieties. These findings indicate the potential utilization of chitin binding POX as a biochemical tool to guide breeding programs to increase resistance to V. dahliae.

Highlights

Recognition of a potential pathogen is required to trigger a defense response in living organisms
We studied the dynamics of peroxidase activity in two varieties of cotton (Gossypium hirsutum L.); one was susceptible and the other resistant to the plant pathogen Verticillium dahliae
In our study we examined the dynamics of POX activity in seedlings of two different cotton varieties infected with weak (T-4) and highly virulent (AN-3) isolates of V. dahliae

Summary

Introduction

Recognition of a potential pathogen is required to trigger a defense response in living organisms. Plants do not produce immunospecific antibodies; some constituents of pathogens can elicit the activation of plant defense pathways. Among these biogenic inductors (elicitors) are proteins, glycoproteins, polyenic fatty acids, and oligosaccharide fragments of fungi wall cells [chitin, β-(1,3)-glucans] [1]. The pathogen related protein PR-9 POX belongs to an enzyme involved in lignin formation [3]. Aver’yanov et al [5] showed an increase in POX activity in rice blast infected plants compared to healthy plants, and researchers have shown that cell wall bound POX produces H2O2 in response to fungal pathogen elicitors [6,7]. Hammond-Kosak and Jones [8] have published an extensive review of the interaction between specific plant pathogen elicitors and receptors that elicit plant resistant genes

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Conclusion