Expression of defense-related genes in papaya seedling infected with Erwinia mallotivora using real-time PCR

C.Y. Wee, H. Muhammad Hanam, M.Z. Mohd Waznul Adly and H.N. Khairun

Abstract

Papaya is an important fruit crop in Malaysia for the domestic and export markets. The papaya industry is currently facing a major threat from the papaya dieback disease for which no effective control measure is known to prevent further spreading of the disease. The causal agent of the disease, Erwinia mallotivora was only identified lately. Hence, to understand the molecular mechanism underlying the host-pathogen interaction, leaves of papaya seedling were infected with a suspension of E. mallotivora at the concentration of 106 cfu and subsequently, the expression profiles of four identified potential defenserelated genes namely peroxidase, aquaporin, leucine-rich protein and zinc finger protein were analysed using quantitative real-time PCR. The expression profiles were captured at seven different time points post-infection at 0, 4, 8, 12, 24, 48 and 72 h respectively. Among the four defense-related genes analysed, peroxidase, zinc finger protein and leucine-rich protein genes were found to be up-regulated at early stage of infection when compared to control. Meanwhile the expression of the aquaporin gene was found to be significantly up-regulated at later stage in response to E. mallotivora infection.

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