Biochemical changes in roots of coconut palms (Cocos nucifera L.) affectedby lethal yellowing

Respiration rates and protein concentrations of lateral and subtending root s of coconut palms were studied at various stages of development of lethal yellowing (LY) disease, including LY-positive symptomless pains, and compar ed to respiration rates and protein concentrations of healthy palms. No vis ual symptoms were apparent in the roots of LY-positive symptomless palms. H owever, respiration rates and protein concentrations were already lower in LY-positive symptomless palms and they continued to decrease as the disease developed. The appearance of root necrosis coincided with the onset of lea f yellowing in above ground parts. Implications of these findings are discu ssed in the context of root damage, as a central process in the mode of pat hogenicity of the disease.