Abstract
During 2010-2011 growing seasons six bacterial isolates were separated from naturally infected girasole plants tubers (Helianthus tuberosus L.) cv. ‘Balady’, showing soft rot, collected from experimental Farm of the Faculty of Agriculture, in El-Minia University, Egypt. Pathogenicity tests showed various virulence for the bacteria isolated from girasole tubers, found pathogenic. These organisms were characterized as rod-shaped, Gram negative, α-methyl-d-glucoside medium, reducing substances from sucrose, phos, phatase activity and deep cavities on pectate medium. Otherwise, diagnostic tests suggested that the pathogen was Erwinia carotovora ssp. carotovora. The isolated bacteria caused soft rot of wounded tubers when inoculated into tissues. The bacterial isolates were compared for their degree of pathogenicity as well as for differences in specific symptoms, induced in different hosts. The tested isolates could infect several host ranges, such as fruits of apricot, apple, olive, lemon, squash, eggplant and potato tubers, bulbs and garlic and onion cloves, roots radish, carrot, sweet potato and rape. On the other hand, no symptoms were exhibited on pods of bean and cowpea, faba bean, fruits of pepper and tomato. The extracts of experimentally diseased girasole tubers were active in pectinase and also in caboxymethyl cellulose at pH 6 compared to enzyme activities in healthy tissues. Also, the isolated bacteria increased the total and reducing sugars in infected tissues.
Highlights
Jerusalem artichoke is grown primarily for tubers which can be eaten fresh or raw, cooked in appetizing ways similar to Irish potatoes, or pickled
Diseased tubers were firstly washed with tap water surface sterilized with 3% sodium hypochlorite solution (NaOCl) for 3 min, washed thoroughly 3 times with sterilized water, the rotted tissues of tuber were put into sterilized mortar and homogenized, left to stand for 20 min, being streaked into plates containing crystal violet pectate modified (CVPM) medium (Ahmed et al, 2000)
Isolation and identification of the causal organisms Six isolates of creamy-white bacteria were isolated from girasole plants showing typical tuber rot symptom (Fig. 1)
Summary
Jerusalem artichoke is grown primarily for tubers which can be eaten fresh or raw, cooked in appetizing ways similar to Irish potatoes, or pickled. Bacteria soft-rot caused by Erwinia carotovora ssp. The objective of this investigation is to isolate and identify the pathogenic agent, involved or associated, soft-rot disease of girasol tubers at El-Minia governorate. Pathogenicity tests on girasole tubers The pathogenicity of the bacterial isolates was determined by inoculating intact, unblemished, healthy tubers.
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call