Wall ultrastructure and biochemical features of the Juglans regia L. and Juglans nigra L. male gametophyte

Calzoni, G. L.; Speranza, Anna Maria; Caramiello, Rosanna; Piccone, G.; Zannini, Piero

doi:10.1007/bf00198858

Cited by 7 publications

(6 citation statements)

References 18 publications

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“…The electron-translucent spaces in Zone 2 are called lumina. The stratification of the pecan pollen wall was like that recently described for Juglans (Calzoni et al, 1990).…”

Section: Discussionsupporting

confidence: 76%

External Morphological Characteristics for Periods during Pecan Microspore and Pollen Differentiation

Yates¹,

Sparks²

1992

jashs

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Catkin external morphological characteristics of a protogynous (`Stuart') and a protandrous (`Desirable') cultivar of pecan [Carya illinoensis (Wangenh.) C. Koch] were related temporally to the differentiation of microspore and pollen grains. Reproductive cell development was divided into seven periods based on evaluations of number, location, and intensity of staining of the nucleus and/or nucleolus; and vacuolization and staining intensity of the cytoplasm. Catkins with anthers and bracteoles enclosed by bracts did not have reproductive cells that were matured to free microspore. Free microspore developed only after bracteoles became externally visible. The Period 1 nucleus was at the periphery of the cell and a large central vacuole was present; at Period 2, the nucleus was at the center and vacuolation had been reduced. As the angle between the bract and catkin rachis increased to 45°, vacnolation was reduced as the nucleus enlarged and moved to a central location in the microspore (Periods 3 and 4). The majority of the pollen grains were binucleate, and the generative nucleus became elliptical (Periods 5 and 6) by the time anthers became externally visible. Acetocarmine staining intensity of cellular components masked the presence of the generative nucleus (Period 7) just before anther dehiscence. Staining reaction for protein was positive from Period 1; starch from Period 3; lipids and polyphenols from Period 5. The mature pollen grain was abundant in stored reserves of starch and lipids and had a wall with a thicker exine than intine as demonstrated by acetolysis.

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“…The electron-translucent spaces in Zone 2 are called lumina. The stratification of the pecan pollen wall was like that recently described for Juglans (Calzoni et al, 1990).…”

Section: Discussionsupporting

confidence: 76%

External Morphological Characteristics for Periods during Pecan Microspore and Pollen Differentiation

Yates¹,

Sparks²

1992

jashs

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“…The intine is often noticeably irregular in thickness and permeated by cytoplasmic channels. The stratification of the walnut cultivars' pollen wall is similar to those described for J. regia (Colzoni et al, 1990) and pecan (Yates and Sparks, 1992).…”

Section: Resultssupporting

confidence: 71%

“…The appearance of the cross-sections of the pollen walls was similar between walnut cultivars. The exine was comprised of sexine, which is thicker than the underlying nexine; the former appeared as a strong tectum that was traversed by thin channels and decorated by spinulose processes as shown by Colzoni et al (1990). The bacula was more sparse and without lamellar structure (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Although there have been some descriptions of pollen morphology in Juglandaceae (Stone et al, 1964;Ueno, 1975;Whitehead, 1963), studies of walnut are sparse. Colzoni et al (1990) described the pollen wall ultrastructure of Juglans regia and Juglans nigra. Evrenosoglu and Mısırlı (2009) determined pollen morphology and pollen size in'Kaplan 86' and 'S xebin' walnut cultivars.…”

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confidence: 99%

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Anther and Pollen Morphology and Anatomy in Walnut (Juglans regia L.)

Mert¹

2010

horts

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The morphology and ultrastructure of anthers and pollen grains were described for eight walnut (Juglans regia L.) cultivars (Şebin, Bilecik, Kaman I, Kaplan 86, Yalova 3, Pedro, Hartley, and Franquette) using light microscopy and scanning and transmission electron microscopy. Anther and pollen dimensions and pollen production capabilities were also determined. The mean number of stamens per staminate flower (14.90 to 20.03) and mean anther dimensions (1412.5 to 2553.5 μm in length and 849.0 to 1145.5 μm in width) differed significantly among the cultivars. The number of pollen grains per anther also varied significantly and ranged from 4720 to 9840 among the cultivars. The pollen grains of walnut plants are spherical in shape (nearly circular) and pantocolporate (with many colporate apertures on the exine). The pollen surface is microechinate with spiniferous projections. The germination pores are circular and nonbordered. Pollen grain length varied from 33.35 to 37.50 μm in the examined cultivars. The ultrastructure of the pollen walls was similar between walnut cultivars. The exine was comprised of nexine and sexine, which was thicker than the underlying nexine. The sexine appeared as a strong tectum that was traversed by thin channels and decorated with spinulose processes. The thicknesses of the various layers of the pollen wall were as follows: intine: 82.1 to 200 nm; exine: 793.1 to 1161.1 nm; and total wall: 954.4 to 1327.8 nm.

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“…Conversely, if pollen is starchless at maturity, it means that all starch has been hydrolysed during maturation (Cle´ment and Pacini 2001). In other cases, pollen classified as starchless in the literature, such as that of Juglans regia and J. nigra (Baker and Baker 1979), has been found to contain starch at maturity (Calzoni et al 1990). All this means that hydrolysis and polymerisation of starch are of physiological significance and are a response to certain environmental parameters, such as changes in RH and temperature, besides preparing pollen for dehydration and rehydration (Buitink et al 1996;Hoekstra et al 1989Hoekstra et al , 2001.…”

Section: Variations In Soluble and Insoluble Pollen Carbohydratesmentioning

confidence: 97%

Ripe pollen carbohydrate changes in Trachycarpus fortunei: the effect of relative humidity

et al. 2006

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Pollen of the palm Trachycarpus fortunei was kept at 25°C and relative humidities (RH) of 20, 55 and 98%. Changes in viability, water content and carbohydrates were measured over 2-17 days. Water content remained almost constant at 20 and 50% RH and increased dramatically at 98%. Pollen viability and germination rate remained almost constant over 14 days at 20% RH and decreased to about 2% after 7-9 days at 55% and to even less at 98% RH. Although the three experimental conditions were constant, qualitative and quantitative variations in pollen carbohydrates were recorded, even after pollen had lost its viability. The quantities of mono-, di-and polysaccharides varied with the period of pollen storage at the various RH. The greatest changes in glucose, fructose and sucrose content were recorded at 55 and 98% RH. At these relative humidities, maximum glucose and fructose content and minimum sucrose content occurred at maximum water content. Starch was not present in mature pollen but appeared and peaked after 7-9 days of pollen storage at 55 and 98%. Appearance of starch coincided with an increase in pectin content. PAS-positive cytoplasmic polysaccharides showed an increasing trend at 20% RH. A relation was found between pollen viability, water content and monosaccharide content. Pollen viability and germination capacity remained high at 20% RH for 14 days. At this relative humidity, pollen water, glucose and fructose contents remained almost constant, while sucrose reached its maximum value. The fluctuations of more complex carbohydrates (starch, pectins and PAS-positive cytoplasmic polysaccharides) were less easy to interpret. Changes observed under experimental conditions could simulate processes occurring in nature during pollen presentation and dispersal.

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Wall ultrastructure and biochemical features of the Juglans regia L. and Juglans nigra L. male gametophyte

Cited by 7 publications

References 18 publications

External Morphological Characteristics for Periods during Pecan Microspore and Pollen Differentiation

External Morphological Characteristics for Periods during Pecan Microspore and Pollen Differentiation

Anther and Pollen Morphology and Anatomy in Walnut (Juglans regia L.)

Ripe pollen carbohydrate changes in Trachycarpus fortunei: the effect of relative humidity

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