Elimination Processes by Glands

Lüttge, Ulrich; Pitman, M. G.; Hill, A. E.; Hill, B. S.; Schnepf, E.

doi:10.1007/978-3-642-66230-0_5

Cited by 17 publications

(15 citation statements)

References 183 publications

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“…July-September 2017 For both nectaries with and without stomata, the accumulation of sugars inside the gland establishes the "water potential gradient" required for exuding nectar. According to Lüttge & Schnepf (1976), an alternative driving force may be the modification of sugars by gland-cell metabolism, or by the presence of invertases on the gland surface or in the released nectar itself. Cell wall invertases are important for phloem sugar unloading (Roitsch 1999) and are required for nectar production in Arabidopsis (Ruhlmann et al 2010).…”

Section: Stomata-free Nectariesmentioning

confidence: 99%

How does the nectar of stomata-free nectaries cross the cuticle?

Paiva

2017

Acta Bot. Bras.

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In many glandular structures, departure from the cell is only one step in the process of exudate release to the plant surface. Here the set of events that lead nectar to the external environment is presented and discussed mainly for stomata-free nectaries. After being synthesized, the nectar or some of its component needs to be released to the environment where it performs its functions. Nectar precursors derived from cell metabolism need to cross several barriers, such as the cell membrane and cell wall, in order to become nectar. Th en the nectar must cross the cuticle or pass through stomata in order to be off ered to plant mutualists. Release through stomata is a simple mechanism, but the ways by which nectar crosses the cuticle is still controversial. Hydrophilic pathways in the cuticle and repetitive cycles of rupture or cuticle detachment are the main routes for nectar release in stomata-free nectaries. In addition to nectar, there are other exogenous secretions that must leave the protoplast and reach the plant surface to perform their function. Th e ways by which nectar is released discussed herein are likely relevant to understanding the release of other hydrophilic products of the secretory process of plants.

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Section: Stomata-free Nectariesmentioning

confidence: 99%

How does the nectar of stomata-free nectaries cross the cuticle?

Paiva

2017

Acta Bot. Bras.

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“…It has been suggested that hydrolysation of sucrose into its monomers may play a role in forming a sink for sugars in the nectariferous tissue. .A.s a result, a sucrose concentration gradient could be maintained which causes a passive flow of sucrose from the sieve elements to the nectarsecreting cells (see Luttge & Schnepf, 1976;Luttge, 1977;Meyberg & Kristen, 1981). However, this cannot be the case in nectaries where sucrose is the dominant sugar secreted.…”

Section: Nectar and Its Sourcementioning

confidence: 99%

“…More recently, secretory tissues have also figured in considerations of the co-evolution of plants and animals (Levin, 1973;Baker & Baker, 1975;Bentley, 1976;Cruden, Hermann & Peterson, 1983). However, the majority of studies over the last 30 years have been biochemical or ultrastructural (see reviews by Metcalfe, 1967;Thurston &Lersten, 1969;Thomson, 1975;Hill & Hill, 1976;Luttge & Schnepf, 1976 and books by Schnepf, 1969 a;Vassilyev, 1977;Fahn, 1979a).…”

Section: Intronuctionmentioning

confidence: 99%

Secretory tissues in vascular plants

1988

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SUMMARY Secretory tissues occur in most vascular plants. Some of these tissues, such as hydathodes, salt glands and nectaries, secrete unmodified or only slightly modified substances supplied directly or indirectly by the vascular tissues. Other tissues secreting, for instance, polysaccharides, proteins and lipophilic material, produce these substances in their cells. The cells of secretory tissues usually contain numerous mitochondria. The frequency of other cell organelles varies according to the material secreted. In most glandular trichomes the side wall of the lowest stalk cell is completely cutinized. This prevents the secreted material from flowing back into the plant. The salt glands in Atriplex eliminate salt into the central vacuole of the bladder cell but, in other plants, the glands secrete salt to the outside. Different views exist as to the manner in which salt is eliminated from the cytoplasm. According to some authors, the mode of elimination is an eccrine one, while others suggest the involvement of membrane‐bound vesicles. Nectar is of phloem origin. The pre‐nectar moves to the secretory cells through numerous plasmodesmata present in the nectariferous tissue. Nectar is eliminated from the secretory cells by vesicles of either KR or dictyosomal origin. In some cases, both organelles may be involved but an eccrine mode of nectar secretion has also been suggested by some authors. Carbohydrate mucilages and gums are synthesized by dictyosomes but virtually every cell compartment has been suggested as having a role on the secretion of lipophilic substances. Most commonly, plastids are implicated in the synthesis of lipophilic materials but KR may also play a part. In some cases lipophilic materials may be transported towards the plasmalemma in the KR. Resin and gum ducts of some plants develop normally or in response to external stimuli, such as microorganisms or growth substances. Among the latter, ethylene is the most effective. During the course of evolution, secretory tissues seem to have developed from secretory idioblasts scattered among the cells of the ordinary tissues. Subsequently ducts and cavities developed and finally secretory trichomes.

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“…Trichomes can be unicellular or multicellular and have been shown to function in the secretion of a range of compounds, including inorganic salts (Thomson et al 1988), sugars (Findlay 1988), oils, and proteins (Liittge and Schnepf 1976). However, chickpea is the only known example of trichomes in which the primary function is the secretion of organic acids.…”

Section: Introductionmentioning

confidence: 97%

Ultrastructure of organic acid secreting trichomes of chickpea (Cicer arietinum)

Lazzaro¹,

Thomson²

1989

Can. J. Bot.

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The acid-secreting trichomes of chickpea (Cicer arietinum L.) were composed of 18 cells, including 1 basal cell, 3 elongate stalk cells, and 14 head cells. A subcuticular secretion chamber with cuticular pores was present above the head cells at the trichome tip. The basal and stalk cells had large central vacuoles, endoplasmic reticulum, mitochondria, and small vacuoles. In the stalk cells, these small vacuoles were aligned along microtubles extending from the bottom to the top of the cells. Head cells had more dense cytoplasm than stalk cells and also had numerous mitochondria and small vacuoles. A labyrinth of tubules and vesicles at the edges of the head cells contained granular material similar to that observed in the extraplasmic space of the head cell and in the secretion chamber. In older head cells, the tubules were thinner and lacked granular material, the cells contained sequestering membranes and vacuoles, and calcium oxalate crystals were observed in the extraplasmic space. Plasmodesmata were not observed between the basal cell and the surrounding mesophyll cells, although numerous plasmodesmata with associated desmotubules and endoplasmic reticulum connected the trichome cells. Chloroplasts were not observed in the head or stalk cells, whereas the basal cell had small chloroplasts with reduced thylakoid networks and the mesophyll cells had large chloroplasts with well-developed thylakoids that may provide the fixed carbon for organic-acid secretion.

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Elimination Processes by Glands

Cited by 17 publications

References 183 publications

How does the nectar of stomata-free nectaries cross the cuticle?

How does the nectar of stomata-free nectaries cross the cuticle?

Secretory tissues in vascular plants

Ultrastructure of organic acid secreting trichomes of chickpea (Cicer arietinum)

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