Hyperplastic Phloem in Sugarbeet Leaves Infected With the Beet Curly Top Virus

Abstract

Electron microscopy of sugarbeet leaves infected with the beet curly top virus confirmed earlier findings by light microscopy that the hyperplastic phloem consists mainly of sieve elements that are more or less abnormal in structure. Some parenchyma cells and occasional companion cells may be present. The hyperplastic phloem develops in the place of normal phloem and sometimes in the adjacent ground tissue and the xylem. The sieve elements vary in shape and may be haphazardly arranged. The protoplasts of the sieve elements have the usual characteristics of this type of cell. The sieve element plastids develop from chloroplasts if the hyperplasia occurs in chloroplast‐containing parenchyma cells. The cell walls have sieve areas that often are less well differentiated than those of normal sieve elements. The hyperplastic growth in the phloem of curly top diseased plants is discussed with reference to plant tumors induced by certain other plant viruses.

Global Analysis of Arabidopsis Gene Expression Uncovers a Complex Array of Changes Impacting Pathogen Response and Cell Cycle during Geminivirus Infection

“…These parallels suggest that geminiviruses and nanoviruses interact with their hosts through conserved mechanisms that ultimately lead to the establishment of an endocycle. However, hyperplasia and enations have been observed for a few geminivirus/host combinations, indicating that some plant DNA viruses can induce mitosis (Esau and Hoefert, 1978;Briddon, 2003). The capacity to induce cell division is associated with the viral C4 protein (Latham et al, 1997), but C4 is not essential for infection (Stanley and Latham, 1992).…”

Chloroplast ultrastructure in two Crassulacean species and an F1 hybrid with differing biomass δ13C values

“…Leaves of Sedum greggii and Cremnophila linguifolia and of the hybrid {S. greggii x C. linguifolia) were prepared for electron microscopy using a number of different fixation procedures (Esau & Hoefert, 1978;Shoup, Overton & Ruddat, 1980;Ogawa, Miyake & Maeda, 1980), but in most cases samples were fixed in 5% glutaraldehyde and 4% paraformaldehyde in 0.05 kmol m~^ phosphate buffer at pH 7.2 for 5 h, rinsed in buffer, post fixed in 2% OSO4 in 0.05 kmol m-p hosphate buffer for 15 h on ice, then dehydrated in acetone and embedded in Spurr low viscosity resin (Polysciences). Samples were fixed at 15.00 h. The plants had been grown together in a greenhouse exposed to long summer days with no artificial lighting.…”

Anatomical effects of 2,4-DB on tomato internodes

“…It is likely that 2,4-DBthat internodal tissues displayed tolerance to 2,4-DB and sensitive plants lack means, such as conjugation, that 0008 prevent 2,4-DB from being P-oxidized to herbicidal concentrations of 2,4-D (Fawcett et al 1952;Norris and Freed 1966;Smith 1979). During the discussion of the results of the present study, similarities between the anatomical effects of 2,4-DB and the reported anatomical effects of certain growth regulators and pathogens will be noted since it is probable that all these stimuli operate by disturbing the plant's control over endogenous growth regulators (Sachs 1975;Esau 1976;Esau and Hoefert 1978).…”

“…Our study is the first to show that a growth regulator (2,4-DB) can induce the differentiation of supernumerary sieve tube members. Esau (1961) and Esau and Hoefert (1978) indicated that the pathogens may induce supernumerary sieve tube members by altering the plant's normal control and synthesis of certain gowth-regulators. Supernumerary sieve elements have been studied most intensively by Esau and her colleagues as one symptom of some viral and mycoplasmal diseases (Esau 1941(Esau , 1977Rasa and Esau 1961).…”

“…14, 16). Esau and Hoefert (1978) studied the sequence of this type of segmentation in the hyperplastic phloem of sugarbeet using the electron microscope. 17).…”