Phytoplasma associated with mango malformation disease in Egypt.
El-Banna O. H. M., El-Deeb S. H.
Author Affiliation: Plant Pathol. Dept., Fac. of Agric., Cairo Univ., Cairo, Egypt.
Egyptian Journal of Phytopathology 35 : 141-153
Abstract : Scanning electron microscopy (SEM) of different mango samples showing typical symptoms of malformation disease was conducted. The investigations revealed the presence of phytoplasma units in the cortical cells as well as parenchymatous cells of vascular tissues of rachises and petioles of mixed inflorescences (phyllody symptoms) of both Hindy and Taymor mango cultivars. Different populations of phytoplasma units were observed in the investigated sections. The diameter of such units ranged between 0.6-0.8 µm. Budding and binary fission of phytoplasma were also observed as a developmental stages of its growth. In addition, a histological study was conducted to fetch how far the different tissues were affected. In general, tannic sacs of all studied parts were increased in their frequency and density due to infection. The resin ducts of the infected samples of both leaf petiole and rachis showed bigger diameter. Phloem obliteration was clearly observed, while the cambium and its cambial derivatives were disorganized.