The Plant Cell: Aspects of Its Form and Function

Correlation of Pectolytic Enzyme Activity with the Programmed Release of Cells from Root Caps of Pea (Pisum sativum)

“…These shed cells, thought to be a by-product of root cap turnover, have traditionally been referred to as "sloughed" root cap cells because of the belief that the cells were dead (21,24,28). To the contrary, populations of shed root cap cells from more than 30 species in 10 families examined, including cereals and legumes, exhibit 90 to 100% viability (12).…”

Living plant cells released from the root cap: A regulator of microbial populations in the rhizosphere?

“…The cells are frequently not included in photographs of root caps (for example, Bennet et al, 1987;Hinch and Clarke, 1980;Moore and McClelan, 1983;Rost and Jones, 1988) because of the ease with which they do separate from the root: most germination procedures and all washing methods remove virtually all of them. Although outer root cap cells have long been known to slough from the root, they have been viewed as a passive and nonspecific source of carbon and nitrogen compounds that are released as the cells deteriorate (Voeller et al, 1964). Recent studies suggest that BRD cells have the potential to play a more specific role in regulating the composition of microorganism populations in the rhizosphere.…”

“…Physical protection was thought to be provided by two means: The polysaccharide slime produced by the root cap was believed to lubricate passage of the root through soil. In addition, dying cells released from the cap were thought to provide mechanical protection against abrasion of the tip (Voeller et al, 1964). However, studies from McCully's laboratory have raised questions about the generally accepted picture of dying root cap cells and the slime that encase them as serving a rather passive function in assisting plant root growth.…”

Residue Reviews / Rückstands-Berichte

“…Plasmodesmata.-The important role played by plasmodesmata in the intercellular transport of numerous substances is well documented by research reports, and more recently by ultrastructural studies which generally substantiate this role. The subject has been discussed comprehensively by SCHUMACHER (1967 a), VOELLER et al (1964), and several other reviews listed in the introduction. Although categorized here under the epidermis, some of the work described also pertains to plasmodesmata of parenchyma cells where the basic structure and function of these components are probably similar to those of the epidermis.…”

“…They are apparently absent in some plant species; their demonstration in others is indeed markedly influenced by environmental conditions, toxicants, and techniques of fixation for microscopic examination. Details of these factors, as well as structure and function in foliar absorption and cuticular excretion, have been discussed in a number of reviews cited in the introduction, with particularly comprehensive consideration by FRANKE (1964 and, LINSKENS et al (1965), NAPP-ZINN (1961), andVOELLER et al (1964).…”