Erwinia carotovora subsp. carotovora與Erwinia chrysanthemi引起籮蔔細菌性軟腐病

Abstract

Bacterial soft rot of radish frequently occurs in Taiwan and was reported to be caused by Erwinia carotovora subsp. carotovora (Ecc). In 1988, a total of fifty strains of soft-rotting Erwinia was isolated from diseased radish tissues collected from several fields in the central and southern parts of Taiwan, among them, forty-six strains were identified as Ecc, while the other four strains were Erwinia chrysantherni (Ech) with phenotypic characteristics similar to the strains in subdivision II according to Dickey’s classification. Strains of both Ecc and Ech induced soft rot extensively on a wide variety of vegetable tissues. However, Ech strains were more virulent to bulb scales of onion than most Ecc strains. The rotting ability of Ech on radish taproot tissues was also stronger than that of Ecc especially at higher temperature (32℃). In addition1, when radish taproot tissues were inoculated with cell suspensions of both Ecc and Ech in a 1:1 ratio, Ecc was dominant in the rotted tissues at 28℃ or below, but Ech became dominant at higher1temperature (32℃). 蘿蔔細菌性軟腐病於台灣田間經常可見，然對其病原細菌之特性，未曾有較深入之探討。民國77年間筆者等自台灣中南部不同地區之蘿蔔田，採回罹軟腐病之蘿蔔塊根與葉柄組織，共分離了50個Erwinia屬軟腐細菌菌株，經生理生化特性測定結果，其中46個菌株為Erwinia carotouora subsp. carotouora (Ecc)，另4個菌株為Erwinia chrysanthemi (Ech)，此4個Ech菌株皆屬於Dickey分類體系之第II型。Ecc與Ech菌株對許多蔬菜組織常具有強之致腐能力，然而Ecc與Ech菌株在洋蔥鱗片上之致腐能力，則有很大差異，許多Ecc菌株對洋蔥鱗片之致腐能力很弱，而Ech菌株則很強。又溫度可影饗此兩種軟腐細菌之致腐能力，於蘿蔔塊根組織上，Ech菌株常較Ecc菌株之致腐能為強，尤其於較高的溫度下(32℃)。以等量之Ecc與Ech細菌同時接種於蘿蔔塊根組織，在較高的溫度下(32℃)，於軟腐組織中Ech之族軍較Ecc為優勢