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

Abstract

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.

Topography of the Cotyledon Surfaces and Adjoining Seed Coat of Chickpea (Cicer arietinum L.) Genotypes Differing in Milling Performance

“…4D), but also on the other genotypes to a lesser degree, with the exception of Amethyst and 9105-33 N, which had none. Although they are known to exist in the acid-secreting trichomes of chickpea leaves (Lazzaro and Thomson 1989), no reports of crystals in their seeds could be found in the literature. McNair (1932) reported the presence of calcium oxalate crystals in 215 plant families, and they have been found in the cotyledons (Wolf et al 1981;Ilarslan et al 2001) and seed coats (Arnott and Webb 1983;Bewley and Black 1994) of some leguminous seeds.…”

Endocytosis of Lanthanum Nitrate in the Organic Acid‐secreting Trichomes of Chickpea (Cicer Arietinum L.)

“…Chickpea trichomes secrete organic acids, primarily malate and oxalate (Lauter and Munns, 1986), but neither stalk nor head cells of the trichomes contain chloroplasts (Lazzaro and Thomson, 1989). Although the basal cell does contain small chloroplasts, they are ten times smaller in diameter than the chloroplasts in adjacent mesophyll cells and have less-developed grana (Lazzaro and Thomson, 1989).…”

“…Although the basal cell does contain small chloroplasts, they are ten times smaller in diameter than the chloroplasts in adjacent mesophyll cells and have less-developed grana (Lazzaro and Thomson, 1989). Since there are no plasmodesmata connecting the basal cell with the adjacent epidermal and mesophyll cells (Lazzaro and Thomson, 1989), fluid phase endocytosis in the stalk cells may playa role in the uptake of carbon substrate into the trichomes. Since there are no plasmodesmata connecting the basal cell with the adjacent epidermal and mesophyll cells (Lazzaro and Thomson, 1989), fluid phase endocytosis in the stalk cells may playa role in the uptake of carbon substrate into the trichomes.…”

“…Secretions collect in a subcuticular chamber at the top of the trichome and exude through pores in the cuticle (Schnepf, 1965;Lazzaro and Thomson, 1989). Secretions collect in a subcuticular chamber at the top of the trichome and exude through pores in the cuticle (Schnepf, 1965;Lazzaro and Thomson, 1989).…”

“…Secretions collect in a subcuticular chamber at the top of the trichome and exude through pores in the cuticle (Schnepf, 1965;Lazzaro and Thomson, 1989). Secretory trichomes are present on the leaves, stems, and pods of chickpea plants (Lazzaro and Thomson, 1989), and the secretion of strong acids by these trichomes probably deters insect herbivory (Koundal and Sinha, 1983;Rembold and Weigner, 1990). Secretory trichomes are present on the leaves, stems, and pods of chickpea plants (Lazzaro and Thomson, 1989), and the secretion of strong acids by these trichomes probably deters insect herbivory (Koundal and Sinha, 1983;Rembold and Weigner, 1990).…”