The Processes of Anther Dehiscence and Pollen Dispersal Iii. The Dehydration of the Filament Tip and the Anther in Three Monocotyledonous Species

Abstract

SUMMARYThe relationship between anther dehiseenee and dehydration of the filament tip and the connective tissue were followed in Gasteria verrucosa (Mill.) H. Duval, Allium cepa L. and Lilium hybrida ev. ' Enehantment' using various mieroseopical techniques, including direct observations of living tissues in the SEM.In G. verrucosa anther dehiseenee immediately follows anthesis, with concomitant dehydration and shrivelling of the filament tip. In L. hybrida the filament tip dehydrates and shrivels before anthesis. The anthers start to dehisce immediately after anthesis. In A. cepa the filament tip dehydrates and shrivels slowly after anthesis and dehiseenee, which may take up to several days, correlates with the rate of extension of the filament.The attenuated period of dehiseenee in A. cepa may be related to the absence of stomata on the anther. Experiments on xylem conductivity and transpiration reveal that the presence of continuously open stomata on the anthers sets the time of dehiseenee after anthesis in G. verrucosa and L. hybrida.The shrinking filament tip in all three species functions as a hinge which suspends the dangling anther after dehiseenee. The uniformly thickened epidermal cell walls on the anthers opposite the filament prevent the outwardly bending locule walls from embracing the filament.

Control of Abscisic Acid Catabolism and Abscisic Acid Homeostasis Is Important for Reproductive Stage Stress Tolerance in Cereals1

“…In cold-stressed rice anthers, expression was found in guard cells that are located on the connective tissue of rice anthers. Stomata in anthers could play a role in pollen dehiscence in entomophilous plants, where they are associated with nectaries and play a role in sugar secretion (Keijzer et al, 1987(Keijzer et al, , 1996Varassin et al, 2008). The role of these stomata in the selffertilizing plant species rice is unclear, but also Arabidopsis was shown to have functional nectaries (Kram and Carter, 2009).…”

Ethylene regulates the timing of anther dehiscence in tobacco

“…In the last stage before dehiscence, the anthers also dehydrate and there is evidence that this causes the collapse of the cells in the vascular bundle in the tip of the filament (Keijzer et al 1987a(Keijzer et al , 1987b. We show that this did not occur in ethylene-insensitive anthers at stage 12, suggesting that these anthers are less dehydrated (Fig.…”

Morfoanatomía floral de Kallstroemia maxima (Zygophyllaceae)

“…Este tipo de engrosamiento podría estar relacionado con el cierre de los pétalos después de la antesis, ya que en K. maxima las flores abren en la mañana en la zona de Yecapixtla, Morelos, donde fueron recolectadas las muestras que se utilizaron en este estudio. Alrededor de las 11:00 h, el polen está disponible y el estigma receptivo, unas horas después los estambres, alrededor de las 17:00 h, o antes, se giran quedando cerca del estigma, posteriormente también los pétalos se pliegan de forma convoluta, manteniendo unidas a ambas estructuras, como fue reportado por Porter (1969a); este mecanismo es similar al que ocurre en las anteras, donde debido a los engrosamientos del endotecio y asociado a cambios de humedad, las paredes se giran hacia adentro, permitiendo la apertura de la antera y la liberación del polen (Keijzer et al, 1987;Wilson et al, 2011). No obstante, es necesario realizar estudios de los cambios anatómicos asociados a los procesos de polinización que permitan comprobar estas hipótesis.…”

“…Las anteras maduras en K. maxima presentan cutícula estriada y estomas hacia la zona del conectivo; Keijzer et al (1987) han señalado que la presencia de estomas y estriaciones cuticulares a nivel de la antera pueden contribuir a aumentar la evaporación del agua y facilitar su dehiscencia. Aunque Porter (1969a) señaló que la dehiscencia de las anteras es introrsa, en el presente estudio se observó que la dehiscencia es longitudinal y lateral.…”