Vegetative Shoot Meristems

2009 ◽  
pp. 1-12 ◽  
Author(s):  
Dave Jackson
Keyword(s):  
Vegetative Shoot ◽  
Shoot Meristems

scholarly journals Expression of maize KNOTTED1 related homeobox genes in the shoot apical meristem predicts patterns of morphogenesis in the vegetative shoot

Development ◽  
1994 ◽  
Vol 120 (2) ◽  
pp. 405-413 ◽  
Author(s):  
D. Jackson ◽  
B. Veit ◽  
S. Hake
Keyword(s):  
Shoot Apical Meristem ◽  
Leaf Development ◽  
Apical Meristem ◽  
Expression Patterns ◽  
Homeobox Genes ◽  
Homeobox Gene ◽  
Vegetative Shoot ◽  
Lateral Organs ◽  
Floral Meristems ◽  
Shoot Meristems

In this paper we describe the expression patterns of a family of homeobox genes in maize and their relationship to organogenic domains in the vegetative shoot apical meristem. These genes are related by sequence to KNOTTED1, a gene characterized by dominant neomorphic mutations which perturb specific aspects of maize leaf development. Four members of this gene family are expressed in shoot meristems and the developing stem, but not in determinate lateral organs such as leaves or floral organs. The genes show distinct expression patterns in the vegetative shoot apical meristem that together predict the site of leaf initiation and the basal limit of the vegetative ‘phytomer’ or segmentation unit of the shoot. These genes are also expressed in the inflorescence and floral meristems, where their patterns of expression are more similar, and they are not expressed in root apical meristems. These findings are discussed in relation to other studies of shoot apical meristem organization as well as possible commonality of homeobox gene function in the animal and plant kingdoms.

Ontogenetical and experimental studies of the floral apex of Portulaca grandiflora. 1. Histology of transformation of the shoot apex into the floral apex

1969 ◽  
Vol 47 (1) ◽  
pp. 133-140 ◽  
Author(s):  
Siti Raswati Soetiarto ◽  
Ernest Ball
Keyword(s):  
Shoot Apex ◽  
Experimental Studies ◽  
Floral Meristem ◽  
Vegetative Shoot ◽  
Floral Organs ◽  
Mature Flower ◽  
Floral Apex ◽  
Portulaca Grandiflora ◽  
Floral Primordia ◽  
Vegetative Shoot Apex

The vegetative apex was a low dome consisting of two layers of tunica surmounting a very small corpus. Foliar primordia originated as periclines in the flanks of T2. The transition apex became first a steep cone and then a hemisphere. All floral primordia—the two bracts, the two sepals, the several whorls of petals, the several whorls of stamens, and the carpels—originated in the manner of leaves, as periclines in T2 on the flanks of the apex. All appendages, including carpels, were therefore lateral. In the early transition, the apex had a brief stage in which there were three tunica layers, but the inner one was lost with the onset of the sepals. The bracts and the first sepal continued the normal positions of primordia for the vegetative phyllotaxy of 3/8, but with the second sepal, this phyllotaxy was lost, and petals, stamens, and carpels were produced in whorls. While leaves, bracts, sepals, and petals were produced in acropetal sequence, stamens were produced in basipetal sequence, and carpels appeared simultaneously. After carpels were formed, the rest of the floral apex underwent a brief period of expansion growth, achieving a diameter comparable to that of a shoot apex, but its substance was eventually incorporated into the carpel margins, which later produced the ovules. This agrees with the determinate nature of the floral apex. During the development of the first series of floral organs, the floral apex underwent continued increase in area, finally achieving a diameter several times that of the vegetative shoot apex. Its size and form were such that they were compared to those of some inflorescence apices. After development of the first series of floral organs, the subjacent tissues to the floral meristem underwent divisions and elongation at right angles to the axis, causing at first a flattening of the meristem, and eventually a cup-shaped form, with the carpels attached in the bottom of a bowl. The mature flower was thus perigynous, but this development arose quite differently from the perigyny as it is known from ontogenetic studies in the Rosaceae.

Origin and Development of Adventitious Shoot Meristems Initiated on Plant Chimeras

1993 ◽  
Vol 155 (1) ◽  
pp. 259-269 ◽  
Author(s):  
Hui-cheng Tian ◽  
Michael Marcotrigiano
Keyword(s):  
Adventitious Shoot ◽  
Shoot Meristems

scholarly journals The Significance of Macronutrients in Alternate Bearing ‘Nadorcott’ Mandarin Trees

HortScience ◽  
2018 ◽  
Vol 53 (11) ◽  
pp. 1600-1609 ◽  
Author(s):  
Ockert P.J. Stander ◽  
Graham H. Barry ◽  
Paul J.R. Cronjé
Keyword(s):  
Treatment Effects ◽  
Foliar Spray ◽  
Shoot Development ◽  
Citrus Reticulata ◽  
Alternate Bearing ◽  
Vegetative Shoot ◽  
Current Season ◽  
Standard Practice ◽  
Main Determinants ◽  
Fruit Load

The significance of macronutrients nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in leaves was studied in relation with their possible roles in alternate bearing of ‘Nadorcott’ mandarin (Citrus reticulata) trees over a period of three seasons. Fruit load (“on,” a heavy fruit load, vs. “off,” a light fruit load) affected the leaf macronutrient concentrations, and the amount of macronutrients removed through the harvest of fruit, i.e., the crop removal factor (g·kg−1), was consistent in both seasons. The crop removal factors were higher for each macronutrient in “off” trees—harvest of 1 kg fruit removed ≈2.3 g·kg−1 N, 0.3 g·kg−1 P, 3.1 g·kg−1 K, 1.0 g·kg−1 Ca, and 0.4 g·kg−1 Mg, compared with 1.3 g·kg−1 N, 0.2 g·kg−1 P, 1.7 g·kg−1 K, 0.6 g·kg−1 Ca, and 0.2 g·kg−1 Mg in “on” trees. Fruit load per tree (kg/tree) of 84, 110, and 52 kg/tree in “on” trees, however, removed ≈217 g/tree N, 28 g/tree P, 296 g/tree K, 100 g/tree Ca, and 35 g/tree Mg, which was 1.5–6 times more than that of fruit loads of 14, 71, and 16 kg/tree in “off” trees. In “off” trees, N, P, and K, and in “on” trees, Ca accumulated in leaves to between 20% and 30% higher concentrations in season 1, but the higher macronutrient status did not manifest in or consistently correlate with intensity of summer vegetative shoot development in the current season, or intensity of flowering in the next season, the two main determinants of fruit load in ‘Nadorcott’ mandarin. Apart from some anomalies, the concentrations of macronutrients in leaves were unaffected by de-fruiting and foliar spray applications of N and K to “on” trees, and showed no consistent relationship with treatment effects on parameters of vegetative shoot development and flowering. Leaf macronutrients in alternate bearing ‘Nadorcott’ mandarin trees, fertilized according to grower standard practice, are not related to differences in flowering and vegetative shoot development, and appear to be a consequence of fruit load and not a determinant thereof.

Nuclear proteins of quiescent and mitotically active cells in shoot meristems of Tradescantia paludosa

1974 ◽  
Vol 52 (9) ◽  
pp. 2049-2053 ◽  
Author(s):  
R. S. Tobin ◽  
Kyu-Byung Yun ◽  
J. M. Naylor
Keyword(s):  
Nuclear Proteins ◽  
Zone Of Inhibition ◽  
Interphase Nuclei ◽  
Lateral Buds ◽  
Dye Binding ◽  
Tradescantia Paludosa ◽  
Shoot Meristems

In inhibited lateral buds of Tradescantia paludosa, interphase nuclei in the apical zone of inhibition contain higher levels of arginine per unit DNA than those of mitotically active cells in interphase or prophase. Supplementary dye-binding experiments suggest that this reflects a corresponding difference between the composition of the histone complement of chromatin in the two cells populations. The possible implications of this phenomenon are discussed.

scholarly journals Plant Regeneration via Somatic Embryogenesis from Leaf and Floral Explants of ‘Chancellor’ Wine Grape

1970 ◽  
Vol 20 (2) ◽  
pp. 157-170 ◽  
Author(s):  
Richard M.S. Mulwa ◽  
Margaret M.A. Norton ◽  
Robert M. Skirvin
Keyword(s):  
Somatic Embryogenesis ◽  
Embryogenic Callus ◽  
Somatic Embryos ◽  
Basal Medium ◽  
Limiting Factor ◽  
Half Strength ◽  
Conversion Stage ◽  
Cotyledon Expansion ◽  
Floral Explants ◽  
Shoot Meristems

Abundant embryogenic callus was obtained from leaf and floral explants of "Chancellor" grape by continuous culture for 12 weeks on Nitsch and Nitsch basal medium supplemented with 9 μM 2, 4-D + 17 μM IASP + either 1 μM BA or 1 μM TDZ (ECIM) in darkness. They were successfully maintained by a five to six week subculture interval on NN medium containing 2 μM 2, 4-D + 0.2 μM TDZ + 4 μM IASP (LTMM). Near synchronous embryo developed from embryogenic callus on medium containing 10 μM IASP + 8 μM NOA + 1 μM TDZ + 1 μM ABA + 2.5 g/l AC (EDMM).  Individually separated somatic embryos were germinated on both NN and half strength of MS containing 0.5 μM BA + 0.025 μM NAA, respectively; normal plantlet conversion from embryos was low (35%).  Whole fruiting plants were obtained. Aberrant embryo development was characterized by failure to form functional shoot meristems following the initial cotyledon expansion during germination. These observations indicate that the embryo conversion stage of the regeneration is difficult and remains a limiting factor requiring more empirical experimentation for improvement in grape tissue culture.   Key words: Chancellor grape, Regeneration, Somatic embryogenesis   D.O.I. 10.3329/ptcb.v20i2.6895   Plant Tissue Cult. & Biotech. 20(2): 157-170, 2010 (December)

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