23 herbaceous taxa distributed in 9 orders and 10 monocotyledonous families were documented on nature of stomata.
Only arched epidermal cells were observed. Anomocytic, paracytic, tetracytic and hexacytic and mixed stomata were recorded.
Stomata size ranged from 17.47µm ± 0.23 x 16.13µm ± 0.29 in Smilax kraussiana to 58.80µm ± 0.33 x 50.40µm ± 0.39 in Commelina benghalensis and stomata index values varying from 0.57% in Aframomum sceptrum to 14.40% in Rhaphidophora africana were documented in this study.
The present investigation describes abnormal stomata and cytoplasmic connections between guard cells of neighboring stomata in mature leafs of six species of the monocots. The study is made on leaves of Amaryllis reticulate L. Her., Narcissus pseudonarcissus L., Iris langport Wern., Crocus sativus L., Ixiolirion tataricum (Pall.) and Allium cepa L.
Anomocytic stomata type was observed in all species. Several stomata abnormally include single guard cells, aborted guard cells, arrested developments and cytoplasmic connection between guard cells of neighboring stomata was common to all species except in Allium cepa wasn’t observed cytoplasmic connection.
The development and patterning of stomata in the plant epidermis has emerged as an ideal system for studying fundamental plant developmental processes.
Over the past twenty years most studies of stomata have used the model dicotyledonous plant Arabidopsis thaliana. However, cultivated monocotyledonous grass (or Gramineae) varieties provide the majority of human nutrition, and future research into grass stomata could be of critical importance for improving food security.
Recent studies using Brachypodium distachyon, Hordeum vulgare (barley) and Oryza sativa (rice) have led to the identification of the core transcriptional regulators essential for stomatal initiation and progression in grasses, and begun to unravel the role of secretory signaling peptides in controlling stomatal developmental.
This review revisits how stomatal developmental unfolds in grasses, and identifies key ontogenetic steps for which knowledge of the underpinning molecular mechanisms remains outstanding.
La orquídea C. jenmanii es una planta de interés ornamental endémica de Venezuela. En este trabajo se comparó la epidermis foliar en condiciones de orquideario, multiplicación in vitro y aclimatización. Se cultivaron plantas adultas en orquideario y líneas in vitro en medio Murashige-Skoog. Las vitroplantas enraizadas fueron aclimatizadas en un propagador de neblina durante una semana, cámara húmeda por cuatro semanas y orquideario durante tres semanas. Las muestras se procesaron mediante técnicas de microtecnia clásica. Las prácticas de cultivo in vitro indujeron el desarrollo de una epidermis con las siguientes alteraciones de la anatomía normal: mayor tamaño de las células típicas, menor espesor de las paredes anticlinales, menor tamaño de los estomas, además de la formación de estomas y tricomas en la superficie adaxial. En las hojas provenientes de la aclimatización hubo una tendencia a revertirse las alteraciones observadas in vitro, con el incremento de tamaño de los estomas y el engrosamiento de las paredes anticlinales de las células típicas, lo cual sugiere que para lograr su adaptación al orquideario, las hojas sufren cambios en sus células típicas conducentes al incremento de su resistencia mecánica y rigidez. Sin embargo, la permanencia de tricomas glandulares y estomas en la superficie adaxial sugieren que la adaptación de las hojas a las condiciones ex vitro no se completó durante las ocho semanas de aclimatización. Palabras clave adicionales: Propagación in vitro, aclimatización, orquídeas
The orchid C. jenmanii is an important endemic ornamental plant in Venezuela. In this research, leaf epidermal structure development under three environments (orchid house, in vitro multiplication phase and acclimatization) was compared. Adult plants were cultivated in orchid house, and organogenic lines propagated in vitro using Murashige-Skoog medium. Rooted micropropagated plants were acclimatized in a mist propagator for one week, humid chamber for four weeks, and orchid house during three weeks. The samples were processed by means of classical microtechnique procedures. The leaf epiderm in vitro development was abnormal, with increased dimensions of typical epidermic cells, reduction in anticlinal wall thickness, reduction of stomata size, and neo-formation of stomata and epidermic hairs in the adaxial surface. In contrast, leaves developed during acclimatization showed a reversion of abnormalities observed in vitro, with an increase of stomata size and anticlinal walls thickness. However, the permanence of adaxial leaf hairs and stomata suggest an incomplete adaptation of leaves to the external environment during the eight-week acclimatization.
Octoploid (2n = 56) bromegrass (Bromus inermis Leyss.) had significantly larger but fewer stomata than tetraploid (2n = 28) plants at all leaf positions sampled and on both leaf surfaces. Both ploidies showed a similar pattern of stomatal length and frequency at four positions on the culm and three positions on the individual leaf. Stomatal length increased and frequency decreased progressively from the top (LI) to lower (IA) leaves. The tip of the leaf had the largest but fewest number of stomata with the reverse for the base of the leaf.
Seven bromegrass cultivars within the octoploid level differed significantly in stomatal length and frequency of adaxial and abaxial surfaces and at five different leaf positions on the culm. ‘Carlton’ and ‘Blair’ had consistently smaller stomata with greater frequency, whereas ‘Saratoga’ and ‘Red Patch’ had larger, but fewer, stomata. Stomatal length increased while frequency decreased from L1 to L3 and leveled off from L3 to L5 (fifth leaf below panicle). Varietal differences in stomatal length and frequency were mainly associated with the center position of a leaf surface.
Correlations between the adaxial and abaxial surfaces of L1 showed highly significant positive values for both stomatal length and frequency. Stomatal length and frequency were negatively associated at either surface of LI. The ratio length ✕ frequency was affected more by stomatal frequency than length on the same leaf surface. The interrelationships among stomatal and leaf characters and tiller dry weight suggested that a cultivar with lower stomatal frequency is likely to have larger stomata, longer and wider leaves, and greater dry weight/tiller.