Histological Studies of Pinus Halepensis Stem Xylem Affected by Matsucoccus Josephi (Homoptera: Margarodidae)

Abstract

The injury caused by Matsucoccus josephi Bodenheimer ' Harpaz to naturally and artificially infested Pinus halepensis Mill. was studied with special emphasis on the reaction of the cambium to the insect attack and the subsequent changes in the xylem. Scars from stem injury were easily detected macroscopically due to discoloration on the stem cross section and involve narrowing of annual rings at the injury site for several years. Microscopic sections reveal production of abnormal xylem in the injured zone, i. e., lignified parenchyma cells instead of tracheids, curved tracheids and lignified resin ducts. Histological disorganisation is compared with mechanical injuries. Changes in the orientation of cells in the xylem suggest that the effect of infestation is not only mechanical; interrupted polar auxin transport into loops is probably responsible for abnormal xylem formation.

Overgrowth of Douglas fir (Pseudotsuga menziesii Franco) stumps with regenerative tissue as an example of cell ordering and tissue reorganization

“…Occurrence of circular vessels and tracheids, representing special types of the whirled grain pattern, seems particularly interesting. Such observations were previously reported for plants mainly affected by mechanically induced wounds (Aloni and Wolf 1984 ; Lev-Yadun and Aloni 1991 ), insect-caused wounds (Liphschitz and Mendel 1987 ), stem grafts (Küster 1899 ), root grafts (Neef 1922 ), and tumors (Włoch 1976 ). Studies by Sachs and Cohen ( 1982 ), who induced the formation of circular vessels above transverse wounds in Pisum sativum and Phaseolus vulgaris , are of particular interest.…”

The onset of hazel wood formation in Norway spruce (Picea abies [L.] Karst.) stems

“…According to Bangerter (1984) and Larson (1994), the first xylem derivatives that differentiated in wound-induced callus are often formed in a whirled arrangement. Circular elements of the xylem and the gaps filled with traumatic parenchyma were also presented in insect-produced cambial wounds (Kuroda and Shimaji 1984;Liphschitz and Mendel 1987). A disruption of auxin flow in the cambium results in changes to both the orientation and the shape and size of the cellular elements (Aloni 2015;Larson 1994).…”

Ovary of Matsucoccus pini (Insecta, Hemiptera, Coccinea: Matsucoccidae): Morphology, ultrastructure, and phylogenetic implications

“…The occurrence of endosymbionts in the body of the majority of scale insects is connected with their restricted diet (i.e., phloem sap) which is deficient in essential amino acids (see e.g., Baumann, for further details). As members of the Matsucoccidae feed on parenchyma (Liphschitz and Mendel, ) which contains all the essential nutrients, the function of rod‐shaped bacteria in the body of M. pini remains unknown. The presence of these microorganisms in all the elements of the ovariole (trophocytes, trophocyte processes, trophic core, nutritive cords, and oocytes) suggests that they are transovarially transmitted from the mother to the offspring.…”