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Characteristics of Pseudomonas solanacearum E.F. Smith Infecting Ginger(Zingiber officinate Roscoe) in the Philippines
Thesis Abstract:
Eight ginger isolates of Pseudomonas solanacearum collected from five provinces in the Philippines were studied to determine their host ranges, ability to utilize disaccharides or hexose alcohols, colony morphology on agars, ability to produce melanim pigment, ability to cause hypersensitive reaction in tabacco leaves, and theri susceptibilty to five bacteriophage isolates.
Results of articifial inoculations showed that the ginger isolates were avirulent to tobacco, tomato, sweet pepper, peanut, lima bean, cowpea, castor bean and diploid banana (Butuhan). In natural inoculations, all the isolates were found avirulent to tobacco, tomato, sweet pepper, peanut, lima bean, cowpea, castor bean and diploid and triploid banana( Lakatan), and heliconia. All caused severe wilt of ginger in both inoculations.
Under natural conditions, three isolates were weakly virulent to "20-29" tomato, four were virulent to "Yellow Plum" tomato, and three showed varying degrees of virulence to castor bean. Under artificial inoculation, all isolates exhibited varying degrees of virulence to potato, two were weakly virulent to eggplant, five were weakly virulent to abaca and triploid banana, all were weakly virulent to heliconia, and two were weakly virulent to "Giant Cavendish" Banana.
All the isolates were able to oxidize only hexose alcoholos and therefore they belonged to biochemical type 4. All isolates also produced hypersensitive reaction in tobacco after 48 hours. Tests on melanin pigment formation indicated that they could not belong to race 1, since not all isolates had tyrosinase activity.
Attempts to differentiate the ginger isolates from those of other host plants in terms of colony characteristics and phage susceptibility were unsuccessful. Cross-inoculation studies showed taht isolates from other host plants were unable to produce the typical ginger wilt.
The findings reasonably lead to a proposal to classify the P.slanacearum infecting ginger in the Philippines as a new race, race 4, according to the existing classification of the pathogen based on natural host ranges with ginger as an additional differential host.