Association of Lipoxygenase Response with Resistance of Various Cotton Genotypes to the Bacterial Blight Disease

摘要

In cotton plants (Gossypium hirsutum L.), the interaction with the bacterial pathogen Xanthomonas campestris pv. malvacearum (Xcm) is governed by the gene-for-gene concept. The interaction between the cultivar Rcbba B50 and the race 18 of Xcm leads to an hypersensitive reaction (HR); this cultivar is, however, susceptible to the race 20, with the death of the plant as a consequence. Previous work showed that the induced HR was correlated with 9S-lipoxygenase (LOX) activity responsible for lipid peroxidation. A LOX gene (GhLOX1) whose activity is involved in cell death during HR was characterized. In this study, we investigated whether the lipoxygenase response could be related to cotton resistance in different cotton Xcm combinations. Various combinations of R - avr genes were selected to assess whether the GhLOX1 gene transcription and LOX activity could be correlated with the resistance phenotype. Cotton genotypes with the BB, Bb or B genes, or cotton near-isogenic lines containing single B genes (B, b) were infected by race 1, 18 or 20 of Xcm. Phenotypes were analysed for all interactions tested. For incompatible interactions, the LOX response appears to be concomitantly triggered during cotton resistance strengthening the previous evidence that this reaction is a key event of hypersensitive cell death.