Leaf and Bud Initiation in the Gramineae

Sharman, B. C.

doi:10.1086/335298

Cited by 102 publications

(35 citation statements)

References 5 publications

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“…Moreover, as will be seen, they are not readily applicable to the apices of Lolium in which histological zonation is not marked. For these reasons we will therefore use the terms dermatogen, hypodermis, and subhypodermis, as defined by Sharman (1945).…”

Section: Resultsmentioning

confidence: 99%

Inflorescence Initiation In Lolium Temulentum l. VIII. Histochemical Changes At the Shoot Apex During Induction

Knox¹,

Evans²

1966

Aust. Jnl. Of Bio. Sci.

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SummaryShoot apices of Lotium temulentum plants exposed to 1 long day were harvested at the beginning of the long day, and on each of the five following days. Longitudinal sections were stained for DNA (Feulgen), DNA and RNA (methyl greenpyronin or acridine orange fluorescence), or basic nuclear proteins (ammoniacal silver nitrate, fast green, or bromophenol blue, with or without acetylation or deamination).The first sign of inflorescence initiation was the localized increase in RNA in pockets of epidermal and hypodermal cells centrally placed between the leaf pri. mordia. This was apparent within 24 hr after the floral stimulus reached the shoot apex, and increased sharply during the next 24 hr. This localized RNA increase was accompanied by an increase in the size of nuclei and nucleoli, and by greater hetero· geneity within each nucleus in the density of DNA and histone staining at the activated sites which give rise to the spikelet primordia.No evidence was found of a fall in histone content, or of an increase in cytoplasmic histone staining, either in the apex as a whole or at the sites of spikelet differentiation, at any time. With all histone stains the pattern was closely parallel to that for DNA, except in one important respect, namely that the arginine-rich histones appeared to be almost completely absent from nuclei from the summit and flanks of the apex, although high in the central core and at the base of the apex.The nature of floral induction, the origin of spikelets, and their morphogenesis are discussed in terms of these results.

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Section: Resultsmentioning

confidence: 99%

Inflorescence Initiation In Lolium Temulentum l. VIII. Histochemical Changes At the Shoot Apex During Induction

Knox¹,

Evans²

1966

Aust. Jnl. Of Bio. Sci.

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“…Minor differences in the accounts of RosIer (1928) for wheat, Kliem (1937) for oats, and Sharman (1945) for Agropyron are discussed by Barnard (1955), and it is clear that foliage leaves arise as the result of periclinal divisions, usually restricted to the hypodermis and dermatogen just below the apex. These divisions spread laterally and soon give rise to a collar of tissue surrounding the axis (see Plate 3).…”

Section: (D) Cell-size Distribution Within An Apexmentioning

confidence: 99%

The Physiology of Growth in the Wheat Plant I. Seedling Growth and the Pattern of Growth at the Shoot Apex

Williams¹

1960

Aust. Jnl. Of Bio. Sci.

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SummarySeedling growth of wheat in a constant environment is studied over a period of 21 days. Dry weights of leaves, leaf sheaths, stem, and roots are given for 11 occasions. The pattern of dry weight change is also presented in terms of the changing ratios of plant parts.Growth rates of leaf primordia are determined in terms of volume change based on the technique of serial reconstruction.For an ll-day shoot apex, a detailed account is given of cell-size distribution along the leaf primordia and within the apex itself. It is estimated that, prior to the onset of cell enlargement, the mean cell-generation times for the young leaf primordia range from 12 hr to 3 days.An integrated picture of the early growth of the primary shoot is attempted, mainly in terms of the concept of relative growth rate. The rates for leaves and roots are particularly high while seed reserves are available. There is a progressive change in dominance from leaf growth to stem growth. Early growth of each leaf primordium is exponential, but the exponent decreases with leaf number in a rather discontinuous manner. Following the exponential phase, the rates rise to maxima and then fall asymptotically to zero.It is suggested that intra-plant competition for energy substrates may play an important role in determining the pattern of development of the primary shoot of wheat.

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“…The prophyll is the first leaf formed in a new axis and differs from foliage leaves both in shape and arrangement. In grasses, the prophyll is formed as a two-keeled organ, which is also distinct from a foliage leaf (Arber, 1923;Sharman, 1945;Bossinger et al, 1992). Concerning the ear shoot of maize, developmental and clonal analyses suggest that a two-keeled prophyll is formed via congenital fusion of two leaf primordia and that prophyll formation is closely associated with axillary meristem development (Uhrig et al, 1997;Johnston et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Axillary Meristem Formation in Rice Requires the WUSCHEL Ortholog TILLERS ABSENT1

et al. 2015

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Axillary shoot formation is a key determinant of plant architecture. Formation of the axillary shoot is regulated by initiation of the axillary meristem or outgrowth of the axillary bud. Here, we show that rice (Oryza sativa) TILLERS ABSENT1 (TAB1; also known as Os WUS), an ortholog of Arabidopsis thaliana WUS, is required to initiate axillary meristem development. We found that formation of the axillary meristem in rice proceeds via a transient state, which we term the premeristem, characterized by the expression of OSH1, a marker of indeterminate cells in the shoot apical meristem. In the tab1-1 (wus-1) mutant, however, formation of the axillary meristem is arrested at various stages of the premeristem zone, and OSH1 expression is highly reduced. TAB1/WUS is expressed in the premeristem zone, where it shows a partially overlapping pattern with OSH1. It is likely, therefore, that TAB1 plays an important role in maintaining the premeristem zone and in promoting the formation of the axillary meristem by promoting OSH1 expression. Temporal expression patterns of WUSCHEL-RELATED HOMEOBOX4 (WOX4) indicate that WOX4 is likely to regulate meristem maintenance instead of TAB1 after establishment of the axillary meristem. Lastly, we show that the prophyll, the first leaf in the secondary axis, is formed from the premeristem zone and not from the axillary meristem.

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Leaf and Bud Initiation in the Gramineae

Cited by 102 publications

References 5 publications

Inflorescence Initiation In Lolium Temulentum l. VIII. Histochemical Changes At the Shoot Apex During Induction

Inflorescence Initiation In Lolium Temulentum l. VIII. Histochemical Changes At the Shoot Apex During Induction

The Physiology of Growth in the Wheat Plant I. Seedling Growth and the Pattern of Growth at the Shoot Apex

Axillary Meristem Formation in Rice Requires the WUSCHEL Ortholog TILLERS ABSENT1

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