Lf. Pereira et al., The role of a phenylalanine ammonia lyase gene during cassava bacterial blight and cassava bacterial necrosis, J PLANT RES, 112(1105), 1999, pp. 51-60
A partial PCR clone of a PAL gene (MEPAL) was amplified from genomic DNA of
cassava (Manihot esculenta). PAL enzyme activity and MEPAL mRNA levels wer
e measured in leaves of cultivar MCOL 22 following mechanical wounding or i
noculation with 2 bacterial pathogens. MCOL 22 is resistant to Xanthomonas
cassavae, which causes cassava bacterial necrosis and susceptible to X. axo
nopodis pv. manihotis, which causes cassava bacterial blight. PAL enzyme ac
tivity in the resistant interaction was significantly higher than in the su
sceptible interaction or the control. Similarly, MEPAL transcripts were det
ected in leaves during the resistant interaction, but not during the suscep
tible reaction. RFLP analysis with MEPAL revealed a divergence between Sout
h American and African/Asian cultivars and showed promise for MEPAL as a ma
rker for resistance to Xanthomonads.