Sampling and isolation of the bacterial canker disease showed that the disease occurs on branches, flowers, twigs, buds, leaves, and fruits. The most conspicuous symptoms are the cankers that exude gum during late spring and summer on apricot, peach and pear trees. Gumming is common on stone fruit trees, but occurs on trunks, limbs, twigs or fruits when injuries occur. Cankers on the twigs are darkened areas often at the base of buds. On limbs or trunks, they are often darker than the normal bark, sunken in their centers and they may extend for a considerable distance. Moreover, the grown leaves and shoots may be cankered, wilted and died during the growing season. In contrast, leaves and flowers from the other infected buds may remain symptomless. Leaf infections appear as water-soaked spots then become brown and dry. Fourteen bacterial isolates were isolated from different parts of peach, apricot, pear and apple which collected from different localities of Egypt. In this respect, the bacterial isolates coded as Pb-1, Ps-2and Pf-4 were isolated from buds, stems and fruits respectively of peach in Daqahlyia (Mit-Ghamr). Meanwhile, the isolates coded as Rs-3 and Lb-11 were isolated from stem and bud of pear and apple respectively in the same governorate (Mit-Ghamr). On the other hand, the bacterial isolates coded as Pb-5, Pb-6, Ps-13 and Pl-15 were isolated from peach in Qualubia governorate while, As-12 was isolated from apricot in the same governorate. Meanwhile, the isolate coded as Rf-10 was isolated from pear in Qualubia governorate (Moshtohor), while, the isolates coded as Pf-9 and Pb-14 were isolated from flower and buds of peach respectively in Beheira governorate. The isolate Al-8 was isolated from leaf of apricot in the same governorate. Concerning identification of isolated bacteria using the traditional techniques according to their inspected morphological and cultural characteristics, these traditional tests revealed that these isolates may be belong to three genera i.e., Erwinia, Bacillus, and Pseudomonas. Also, the other testes based on the biochemical and physiological characteristics of isolated bacteria revealed finally that two isolates i.e.Rs-3 and Lb-11 could be identified as Erwinia amylovora, while, the isolates i.e. Pb-6, Al-8 and Pb-14 could be identified as Pseudomonas syringae but the isolate As-12 as Bacillus polymyxa. On the other hand, PCR-RAPD amplification by using the primer- OP-A-11 for the three bacterial isolates i.e.Pb-6, Al-8 and Pb-14 which identified as P. syringae by the traditional identification verified that these three isolates are P. syringae were closely related while three other primers proved that they may not be typical isolates.
Key Words: bacterial canker disease, Pseudomonas syringae, Isolates, PCR, Identification, Isolation. |
