Pink disease of pineapple

Pink disease of pineapple

    Causal organism:Pantoea citrea
    History
    • Pink disease was originally described in 1915 in Hawaii.
    • The pathogen responsible for causing pink disease remained obscure and the nature of the pink color formation of the pineapple fruit tissue was not understood.
    • A myriad of bacteria associated with the pineapple plant, many of which originated from the surrounding soil, made identifying the primary cause of the disease extremely difficult.
    • The biochemical basis of the disease was thought to be complex and difficult to elucidate, and was therefore left uncharacterized.
    • Attempts at identifying the pathogen led to implicating several distinct bacteria as the causal agents of pink disease. Gluconobacter oxydans, Acetobacter aceti, and Erwinia herbicola were the prominent suspected species.
    Symptoms
    • Pink disease symptoms are difficult to observe in the field since external symptoms are not apparent.
    • Infections of the foliage is not detectable. Under severe invasion of the fruit by P. citrea, a translucent appearance in the sub-dermal fruit tissue occasionally can be observed.
    • The symptoms become observable when infected fruit preparations are heated during canning process.
    • Heating causes formation of red to rusty brown coloration of the golden yellow tissue of a healthy fruit.
    The Pathogen
    • Pantoea citrea is a Gram-negative, facultative anaerobic, non-spore forming, bacilliform bacterium with physiological and biochemical as well as 16S rDNA features corresponding to those of the Enterobacteriaceae.
    • On nutrient agar and trypticase soya agar medium, the colonies are entire, smooth, glistening, translucent, but not mucoid. The colonies become taupe in color. Pantoea citrea grows readily in pineapple juice as well as in fresh pineapple fruit tissue.
    • Unlike other Pantoea species, P. citrea is unable to utilize citrate or tartrate. Besides the genetic makeup that causes the pink disease reaction in the pineapple fruit, the bacterium elicits the hypersensitive response in tobacco.

    Management

      • Plant breeding for resistance to pink disease has shown some promise.
      • The most promising biocontrol isolate, Bacillus gordonae, reduced disease incidence when applied in combination with insecticides.

Last modified: Saturday, 14 January 2012, 4:56 AM