The Role of a Phenylalanine Ammonia Lyase Gene during Cassava Bacterial Blight and Cassava Bacterial Necrosis

Abstract

A partial PCR clone of a PAL gene (MEPAL) was amplified from genomic DNA of cassava (Manihot escuknta). PAL enzyme activity and MEPAL mRNA levels were measured in leaves of cultiiar MCOL 22 following mechanical wounding or inoculation with 2 bacterial pathogens. MCOL 22 is resistant to Xanthomonas c~s s~v a e , which causes cassava bacterial necrosis and susceptible to X. axonopodis pv. manihotis, which causes cassava bacterial blight. PAL enzyme activity in the resistant interaction was significantly higher than in the susceptible interaction or the control. Similarly, MEPAL transcripts were detected in leaves during the resistant interaction, but not during the Susceptible reaction. RFLP analysis with MEPAL revealed a divergence between South American and African/Asian cultivars and showed promise for MEPAL as a marker for resistance to Xanthomonads.

Cloning of a peroxidase gene from cassava with potential as a molecular marker for resistance to bacterial blight

“…These three cultivars, plus the cultivar Espeto, both from South America, showed a banding pattern distinct from most of the cultivars coming from Asia or Africa. The distinct band pattern between cultivars from different regions has been demonstrated for other cassava genes that are involved in the plant defense mechanism (Pereira et al, 1999). Resistance to CBB in cassava has been described as a polygenic trait (Jorge et al, 2000(Jorge et al, , 2001.…”

Caracterización de la respuesta morfológica de variedades susceptibles y resistentes de yuca (Manihot esculenta Crantz) a la bacteriosis vascular causada por Xanthomonas axonopodis pv. manihotis

“…Estos resultados sugieren fuertemente que los compuestos fenólicos actúan efectivamente como una posible barrera para la expansión de la infección. En concordancia con los resultados anteriores, Pereira et al (22) encontraron que los niveles de la enzima fenilalanina amonioliasa, involucrada en la síntesis de compuestos fenólicos de tipo fenilpropanoides, se incrementa mucho más en el caso de una respuesta de resistencia entre yuca y X. cassavae.…”

Biochemical and histochemical parameters associated with slow blighting of spot blotch (Bipolaris sorokiniana (Sacc.) Shoem.) in wheat (Triticum spp.)

“…) in wheat (Triticum spp. ) phenolics content has been observed in response to fungal infection in a number of systems (Mazeyrat et al, 1999;Pereira et al, 1999). An active role of PAL and phenolics in expression of resistant reaction in various crop species was reported (Nicholson, Hammerschmidt, 1992).…”