Raphide Idioblasts Research Articles

Comparative Morphology, Anatomy and Phytochemistry of Cyrtosperma senegalense (Schott) Engl. and Alocasia macrorrhizos L. (Araceae)

Morphological, anatomical and epidermal studies were carried out on two species of Araceae, Cyrtosperma senegalense (Schott) Engl. and Alocasia macrorrhizos L. to investigate the taxonomic value of their similarities and differences. Morphological features were visually observed. Fresh specimens were dehydrated, wax embedded, mounted, microscopically observed and micrographed. Basic similarities were found in their leaf shape, venation, inflorescence and spathe, seeded fruits, scattered vascular bundles, possession of aerenchyma, and presence of stomata on the abaxial and adaxial leaf surfaces. Conversely, the presence of prickles and sparseness of raphide idioblasts containing a raphide bundle each in C. senegalense distinguishes it from A. macrorrhizos which has abundant raphides. Phytochemical screening shows differences in their alkaloids, saponin, triterpenoids, steroids and glycosides contents. Though these preliminary studies yielded data that revealed their relationship and phytochemistry, further investigations of their cytology using electron microscopy and molecular biology are needed for more diagnostic data to distinguish them from each other and add more incite to their potential in drug discovery.

Unravelling the enigma of seed dispersal in Vanilla.

Vanilla bean is the second most expensive spice in the world. While widely cultivated for centuries due to its importance for industry and gastronomy, its dispersers are unknown. In the present study, I investigated the system of seed dispersal of Neotropical vanillas based on experimental observations, the morpho-anatomy of fruits and seeds, and the effect of dormancy breakdown on seed germination. My results show the central cavity of the fruit contains copious amounts of seed with sclerified coats that are consumed by birds. The combination of gradually opening dehiscent fruits and a well-developed mesocarp rich in raphide idioblasts reinforces the idea that seed dispersal in Vanilla is more adapted to non-chewing animals. The digestive acids of birds sclerify the hard seed coats, breaking dormancy and promoting germination at the beginning of the wet season, which is fundamental for seedling survival and for the establishment of plants in the early stages of development during the rainy season. Zoochory in Vanilla is show for the first time. The chemical scarification of the seed coat is crucial for synchronizing the biological processes involved in seed germination. My evidence on endozoochory and the processes involved in seed germination of Neotropical vanillas provides new insights into understanding of the early evolution of seed dispersal in orchids.

Distribution of Fucosylated Xyloglucans among the Walls of Different Cell Types in Monocotyledons Determined by Immunofluorescence Microscopy

Xyloglucans in the non-lignified primary cell walls of different species of monocotyledons have diverse structures, with widely varying proportions of oligosaccharide units that contain fucosylated side chains (F side chains). To determine whether fucosylated xyloglucans occur in all non-lignified walls in a range of monocotyledon species, we used immunofluorescence microscopy with the monoclonal antibody CCRC-M1. The epitope of this antibody, α-L-Fucp-(1→2)-β-D-Galp, occurs in F side chains. In most non-commelinid monocotyledons, the epitope was found in all non-lignified walls. A similar distribution was found in the palm Phoenix canariensis, which is a member of the basal commelinid order Arecales. However, in the other commelinid orders Zingiberales, Commelinales, and Poales, the occurrence of the epitope was restricted, sometimes occurring in only the phloem walls, but often also in walls of other cell types including stomatal guard and subsidiary cells and raphide idioblasts. No epitope was found in the walls of the commelinids Tradescantia virginiana (Commelinaceae, Commelinales) and Zea mays (Poaceae, Poales), but it occurred in the phloem walls of two other Poaceae species, Lolium multiflorum and L. perenne. The distribution of the epitope is discussed in relation to xyloglucan structures in the different taxa. However, the functional significance of the restricted distributions is unknown.

Types and Location of Calcium Oxalate Crystals in Dieffen-bachia Cultivars

The irritant effect of Dieffenbachia sap is attributed to protelytic enxymes but calcium oxalate crystals are considered to puncture cells and allow enzyme entrance. To date, no detailed study of the location, type, or frequency of calcium oxalate crystals in Dieffenbachia species or cultivars has been undertaken. To do so, three uniform tissue culture plantlets of Dieffenbachia `Carina',`Rebecca' or `Star Bright' were transpanted into 15 cm pots, grown in a shaded greenhouse under 385 μmol·m-2·s-1 and fertigated with 20 N-8.7 P-16.6 K water-soluble fertilizer at N concentrations of 200 mg·L-1 twice weekly. Ten weeks later, samples of stem, root, and leaves were taken from 4 pots of each cultivar to determine the distribution and type of calcuium oxalate crystals in each plant organ via polarized light microscopy. Two types of calcium oxlate crystals, raphides and druses, were found in the stem, leaves and roots. Druse density increased as leaves andd stems matured while the number of raphide idioblasts remained relatively constant. Crystal density was highest at lateral initation sites of buds and roots. Significant differences were found in crystal density among cultivars even though `Carina' and `Star Bright' are sports selected from `Camille'. This suggests that reduction of calcium oxalate density of Dieffenbachia cultivars is possible through breeding.

サトイモ葉柄内のシュウ酸カルシウム結晶細胞の密度および大きさの差異

日本在来のサトイモ14品種群,37品種を供試して,葉柄内のシュウ酸カルシウム結晶細胞の密度および大きさを調査し,以下の結果を得た.供試したすべての品種の葉柄中には防御的束晶細胞および非防御的束晶細胞の2タイプの束晶細胞が観察された.品種群の間で束晶細胞の密度に差異が認められた.また,いくつかの品種群の間では束晶細胞の密度や形状は類似していた.各品種群内における品種間の束晶細胞密度の差異は,一部の品種群以外は認められなかった.いずれの品種も集晶細胞密度は束晶細胞密度より高く,品種群内におけるそれぞれの細胞密度の差もかなり大きかった.14品種群は葉柄の束晶細胞密度により2グループに分類された.低密度グループには,みがしき群,溝芋群,薑芋群,唐芋群,八ツ頭群,蓮芋群,えぐ芋群および赤芽芋幹の8群が区分され,高密度グループには黒軸群,蓮菊芋群,石川早生群,土垂群,筍芋群および檳榔芯群の6群が区分された.葉柄用および芋・葉柄兼用品種群の葉柄内の束晶細胞密度は,芋用品種群のそれより低かった.また,葉柄用品種群の束晶細胞の大きさは比較的小さかった.以上の結果から,束晶細胞の密度および大きさは,サトイモ葉柄用品種の育種において"えぐ味"が少ない個体を選抜するための指標として利用することが可能と考えられる.

サトイモ組織内におけるシュウ酸カルシウム結晶の形成及びその分布

Raphides (needle-like crystals) or druses (sand-like crystals) of calcium oxalate occur in the idioblast in the hypocotyl and cotyledon of taro at the young seedling stage. These crystals develop in the center of the idioblast. The raphide idioblasts differentiate into defensive or nondefensive types. Those in the defensive type are not tightly compact, but are ejected from the pole of idioblasts to the outside. The nondefensive type and druse idioblasts appear initially and their densities increase, accompanied by growth. The defensive type develops in seedlings 60 days after sowing. The densities of the raphide idioblast are highest in the leaf blade, lowest in the corm, and intermediate in the petiole. In the cross sections of the petiole and corm, the densities of raphide and druse idioblasts are higher in the outer tissue than those of the inner tissue. The densities of both raphide and druse idioblasts are high in the aerenchyma and the parenchyma in different tissues; they are more numerous in young tissues than in old ones.

The Role of Druse and Raphide Calcium Oxalate Crystals in Tissue Calcium Regulation in Pistia stratiotes Leaves

Abstract: Ca oxalate crystal formation was examined in Pistia stratiotes L. leaves during excess Ca and Ca‐deficient conditions. Pistia produces druse crystal idioblasts in the adaxial mesophyll and raphide idioblasts in the abaxial aerenchyma. Raphide crystals were previously found to grow bidirectionally, and here we show that Ca is incorporated along the entire surfaces of developing druse crystals, which are coated with membrane‐bound microprojections. Leaves formed on plants grown on 0 Ca medium have fewer and smaller druse crystals than leaves formed under 5 mM Ca (“control”) conditions, while raphide crystal formation is completely inhibited. When plants were moved from 0 to 15 mM (“high”) Ca, the size and number of crystals in new leaves returned to (druse) or exceeded (raphide) control levels. High Ca also induced formation of druse, but not raphide, crystals in differentiating chlorenchyma cells. When plants were transferred from 15 mM Ca to 0 Ca, young druse crystals were preferentially partially dissolved. Oxalate oxidase, an enzyme that degrades oxalate, increased during Ca deficiency and was localized to the crystal surfaces. The more dynamic nature of druse crystals is not due to hydration form as both crystal types are shown to be monohydrate. Part of the difference may be because raphide idioblasts have developmental constraints that interfere with a more flexible response to changing Ca. These studies demonstrate that excess Ca can be stored as Ca oxalate, the Ca can be remobilized under certain conditions, and different forms of Ca oxalate have different roles in bulk Ca regulation.

Floral development in Aphandra (Arecaceae)

The organogenesis of staminate flower clusters and flowers and some observations on the corresponding pistillate structures of Aphandra natalia are described and compared with those of the other two genera in the Phytelephantoideae (Arecaceae). In Aphandra, staminate flowers are borne in monopodial clusters of mostly four (1-6) flowers. Each flower is surrounded by two pairs of subopposite bracteoles and has two rather indistinctly four-parted whorls of perianth parts. Stamen primordia arise on a shallow apical dome and then centrifugally down the sides of a long, angled, and laterally flattened receptacle. Immediately before the staminate bud opens, the floral receptacle below the androecium rapidly elongates, becoming funnel-shaped, with the bracteoles and a perianth sheath adnate to it forming a pseudopedicel. Epidermal and subepidermal layers of these pseudopedicels split at anthesis and release a great number of raphide idioblasts that resemble the pollen grains in shape and size. It is hypothesized that the idioblasts deter pollen feeding or ovidepositing insects. The phylogenetic implications of these findings are important within the Phytelephantoideae and among palms in general.

TAXONOMIC VALUE OF CALCIUM OXALATE CRYSTALS IN MUSA GERMPLASM

Epidermal and histological characterization of Musa species and cultivars were carried out to investigate the descriptor value of calcium oxalate between groups and subgroups of cultivars. Epidermal peels of the bracts of selected plantain and banana cultivars stained with 0.01% safranin solution and permanent mounts of microtometric sections of fruits, bracts and peduncles stained with hydrogen peroxide and silver nitrate were microscopically examined for their crystal content and features. Bract epidermal features discriminate between the ‘AAB’ plantains and ‘AAA’ bananas. The major form of occurrence of calcium oxalate in the vegetative and reproductive tissues is bundle raphide. The bract adaxial epidermis of bananas show the occurrence of raphide idioblasts which contain a bundle raphide each. The idioblasts and bundles are more-or-less absent in the plantain bracts. Calcium oxalate occurs in the fruit peel as bundle raphides and in the pulp as intra-amylar crystals. Histological characterization of Musa germplasm helps to elucidate the limits of diversity in the germplasm.

DISTRIBUTION OF CALCIUM OXALATE CRYSTAL IDIOBLASTS IN LEAVES OF TARO (COLOCASIA ESCULENTA)

Cleared leaves of taro (Colocasia esculenta) were examined microscopically to determine changes in the distribution of both druse and raphide idioblasts during a late developmental process—leaf unfurling and expansion. Druse crystal idioblasts are small spherical cells found throughout the lamina, mostly in subepidermal areas. Two types of raphide idioblasts were observed in taro leaves: the nondefensive raphide idioblasts, which are elongated cells usually found embedded in tissues of the leaf margins; and the defensive raphide idioblasts, also elongated cells, but usually found suspended between mesophyll cells in leaf airspaces. The densities of both druse and raphide cells were highest at the fully furled stage and least in the mature, unfurled stage, after substantial leaf expansion. During leaf unfurling, the raphide cells showed a bilaterally symmetrical distribution during all stages from fully furled to mature, unfurled leaves. The distribution of druse cells was bilaterally symmetrical during the fully furled and unfurled stages, but, during unfurling, when one half of the lamina is unfurled and the other half is still tightly furled, up to 80% of the druse cells were found on the unfurled half of the lamina.

Distribution of Calcium Oxalate Crystal Idioblasts in Leaves of Taro (Colocasia esculenta)

Cleared leaves of taro (Colocasia esculenta) were examined microscopically to determine changes in the distribution of both druse and raphide idioblasts during a late developmental process—leaf unfurling and expansion. Druse crystal idioblasts are small spherical cells found throughout the lamina, mostly in subepidermal areas. Two types of raphide idioblasts were observed in taro leaves: the nondefensive raphide idioblasts, which are elongated cells usually found embedded in tissues of the leaf margins; and the defensive raphide idioblasts, also elongated cells, but usually found suspended between mesophyll cells in leaf airspaces. The densities of both druse and raphide cells were highest at the fully furled stage and least in the mature, unfurled stage, after substantial leaf expansion. During leaf unfurling, the raphide cells showed a bilaterally symmetrical distribution during all stages from fully furled to mature, unfurled leaves. The distribution of druse cells was bilaterally symmetrical during the fully furled and unfurled stages, but, during unfurling, when one half of the lamina is unfurled and the other half is still tightly furled, up to 80% of the druse cells were found on the unfurled half of the lamina.

Comparative morphology of the carpel in the Liliaceae: Tofieldieae

The Tofieldieae consist of Narthecium, Nietneria, Pleea, and Tofieldia. Although the three carpels of the pistil are generally coherent, their bases are separate for a short distance in some species of Tofieldia and in Pleea, where a septal nectary seems to be differentiated. These two genera are also alike in the extension of the chalaza as a filiform hook. The sutures are open at flowering only in some species of Tofieldia. Nietneria is distinguished by its inferior ovary and the alternate structure of the pistil. No raphide idioblasts were found in the carpels of any species.

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.

Comparative morphology of the carpel in the Liliaceae: Baeometra, Burchardia and Walleria

The pistils in Baeometra, Burchardia and Walleria ate tricarpellate, and their ovules are mostly bitegmic. Baeometra has free styles and deep septal invaginations between the carpels. Its pistil is innervated by three dorsal bundles, three compound septal bundles (each of which may divide into two simple septal bundles above), six placental bundles, and six adjoining auxiliary placental bundles. The pistil of Burchardia resembles that of Baeometra, except that there are six simple septal bundles throughout and no auxiliary placental bundles. In Walleria the wings of adjoining carpels are completely fused (except for rare septal glands); there is a single compound style; additional vascular tissue is present in the central axis of the pistil up to the lowermost ovules; the carpels are fused with the floral cup above the base of the locules; and raphide idioblasts are present. Walleria has six “ventral” bundles, each of which appears to be the fusion product of a placental bundle with a simple septal bundle. Tribal affinities of these genera are discussed.