Early Anther Development Research Articles

Timing of morphological and histological development in premeiotic anthers of Nicotiana tabacum cv. Xanthi (Solanaceae)

The tobacco stamen has been the object of many developmental studies, and the organ has more recently become a model for molecular genetic studies of anther differentiation. However, the spatial and temporal details of cellular differentiation of early anther development have never been thoroughly characterized. In the present study, the age of 15 tobacco flowers from plants grown under constant light and temperature was estimated using growth analysis. Prior to tissue fixation for light microscopy, moulds of stamen and anther primordia were made with a dental impression polymer so morphological and histological observations could be made on each tissue sample. Flower ages spanned an 8‐d interval during which petal and stamen initiation occurred, and sporogenous cells reached the leptonema stage of meiosis. The initial development of the tetrasporangiate anther shape largely preceded periclinal division of archesporial initials. Anatomically, periclinal divisions in the hypodermal ∗∗∗(l2) layer were observed before archesporial initials began to divide. These data indicate differences in the cellular basis of tobacco anther development compared to earlier clonal analyses of Datura. The pattern of mitotic cell division associated with microsporangial development suggested modal peaks in division over time. The ability to estimate developmental time in the tobacco anther has implications for future studies directed at understanding mechanisms of anther evolution via heterochrony.

Timing of Morphological and Histological Development in Premeiotic Anthers of Nicotiana tabacum cv. Xanthi (Solanaceae)

The tobacco stamen has been the object of many developmental studies, and the organ has more recently become a model for molecular genetic studies of anther differentiation. However, the spatial and temporal details of cellular differentiation of early anther development have never been thoroughly characterized. In the present study, the age of 15 tobacco flowers from plants grown under constant light and temperature was estimated using growth analysis. Prior to tissue fixation for light microscopy, moulds of stamen and anther primordia were made with a dental impression polymer so morphological and histological observations could be made on each tissue sample. Flower ages spanned an 8-d interval during which petal and stamen initiation occurred, and sporogenous cells reached the leptonema stage of meiosis. The initial development of the tetrasporangiate anther shape largely preceded periclinal division of archesporial initials. Anatomically, periclinal divisions in the hypodermal ∗∗∗(l2) layer were observed before archesporial initials began to divide. These data indicate differences in the cellular basis of tobacco anther development compared to earlier clonal analyses of Datura. The pattern of mitotic cell division associated with microsporangial development suggested modal peaks in division over time. The ability to estimate developmental time in the tobacco anther has implications for future studies directed at understanding mechanisms of anther evolution via heterochrony.

Cytological Differences between a Cytoplasmic Male Sterile Tobacco Cybrid and Its Fertile Counterpart During Early Anther Development

Cytological Differences between a Cytoplasmic Male Sterile Tobacco Cybrid and Its Fertile Counterpart During Early Anther Development

Isolation and developmental expression of Bcp1, an anther-specific cDNA clone in Brassica campestris.

Differential screening of a mature Brassica campestris pollen cDNA library has identified five cDNA clones that represent transcripts expressed exclusively, or at elevated levels, in pollen. We show here that the expression of one of these, clone Bcp1, is tissue specific and temporally regulated. The gene is activated during microspore development, as detected by in situ hybridization. Expression is enhanced at the time of pollen maturation and during pollen germination. In situ hybridization has also shown that Bcp 1 is activated in the tapetal cells in early anther development and continues to be expressed until tapetal dissolution. Homologous transcripts are present in pollen of other taxa of Brassicaceae including Arabidopsis, but not in pollen of any other families tested.

Histological Features of Anthers from Normal and ms3 Mutant Soybean1

Anthers of male‐sterile mutant (ms3) and normal soybean [Glycine max (L.) Merr.] were compared by using a triple‐staining procedure for DNA, polysaccharides and proteins, and a single‐staining procedure for sporopollenin in conjunction with brightfield and fluorescent microscopy. The purpose of this study was to determine at what stage of anther development histological differences were detectable between male‐sterile (ms3) and normal soybean. At the tetrad stage, a prominent greenish‐blue material, visible with the triple‐staining procedure, filled some of the enlarged tapetal cells of anthers of ms3 plants. This material was also autofluorescent and had an affinity for the fluorochrome primuline which identified sporopollenin. By the early microspore stage, microspores of ms3 plants were unusually enlarged and the tapetum surrounding them prematurely degenerated. This abnormality of tapetal behavior seems to be associated with microspore abortion and serves as an early marker for sterility. Other differences noted between the anthers of ms3 and normal plants with the staining procedures used, were variations in the endothecium and the thickness and degree of staining of the microspore and pollen walls. All of these differences suggest that the effect of the ms3 gene in the homozygous condition is expressed during early anther development, probably beginning at meiosis and directly influences the malfunctioning of the tapetum. The results of this study support numerous other published reports on both genetic and cytoplasmic male sterility implicating the tapetum as the primary tissue responsible for male sterility.