Department of Horticulture, University of Maryland, College Park, Maryland, 20742 and Plant Photobiology Laboratory, USDA-ARS, Beltsville, Maryland, 20705, USA.
STRUCTURAL ASPECTS OF THE PRIMARY TISSUES OF THE CUCURBITA PEPO L. ROOT WITH SPECIAL REFERENCE TO THE PHLOEM
Article first published online: 2 MAY 2006
Volume 102, Issue 1, pages 175–192, January 1986
How to Cite
WARMBRODT, R. D. (1986), STRUCTURAL ASPECTS OF THE PRIMARY TISSUES OF THE CUCURBITA PEPO L. ROOT WITH SPECIAL REFERENCE TO THE PHLOEM. New Phytologist, 102: 175–192. doi: 10.1111/j.1469-8137.1986.tb00808.x
- Issue published online: 2 MAY 2006
- Article first published online: 2 MAY 2006
- (Accepted 13 September 1985)
- Cucurbita pepo;
- sieve element;
The primary phloem and associated tissues in the root of Cucurbita pepo L. were examined by light and transmission electron microscopy to provide information on the feasibility of symplastic transport from the sieve-tube members to the cortex in this organ. The structure, distribution and frequency of cytoplasmic connections between the various cell types of the root are reported as well as the cytological characteristics of the various cells. The protoplasts of contiguous cells of the root are joined by various numbers of cytoplasmic connections: plasmodesmata (simple and branched) between parenchymatous elements; pore-plasmodesmata between sieve-tube members and parenchymatous elements (companion, phloem parenchyma or pericycle cells in the Cucurbita root); and sieve-area pores between contiguous sieve elements. The plasmodesmata associated with secondary- and tertiary-state endodermal cells are not constricted by the suberin lamellae. Differences in the frequency of cytoplasmic connections between the various cell types of the primary phloem, pericycle and ground tissue do occur with the highest frequency between sieve-tube members and companion cells. The results indicate that the structure of the C. pepo root may be compatible with a symplastic pathway of phloem unloading and transport to the cells of the ground tissue.