Terminal megasporangiate cones in pinyon pine

1969 ◽  
Vol 47 (2) ◽  
pp. 259-259
Author(s):  
Ronald M. Lanner
Keyword(s):  
Pinus Edulis ◽  
Terminal Position ◽  
Apical Meristems ◽  
Shoot Apical Meristems ◽  
Pinyon Pine

Three megasporangiate cones apparently formed directly by shoot apical meristems were found in a terminal position on a pinyon pine (Pinus edulis Engelm.).

Differentiation of Multiple Shoot Apical Meristems in Mutant Rice with One Embryo Causing Multiple Plumuples

2012 ◽  
Vol 37 (12) ◽  
pp. 2251-2260
Author(s):  
Jing-Yu GUO ◽  
Zhi-Xiong CHEN ◽  
Bing-Yao YANG ◽  
Xin-Fen CHEN ◽  
Xiang-Dong LIU ◽  
...  
Keyword(s):  
Multiple Shoot ◽  
Apical Meristems ◽  
Shoot Apical Meristems

scholarly journals Δ14C PEAKS APPEARING IN EARLYWOOD AND LATEWOOD TREE RINGS (AD 770–780) IN NORTHEASTERN ARIZONA

Radiocarbon ◽  
2020 ◽  
pp. 1-6
Author(s):  
J H Park ◽  
J Southon ◽  
JW Seo ◽  
P P Creasman ◽  
W Hong ◽  
...  
Keyword(s):  
Tree Rings ◽  
High Latitude ◽  
Pinus Edulis ◽  
Lateral Transfer ◽  
Late Winter ◽  
National Monument ◽  
Small Rise ◽  
Pinyon Pine

ABSTRACT The AD 775 peak in Δ14C (henceforth, M12) was first measured by Miyake et al. and has since been confirmed globally. Here we present earlywood and latewood Δ14C values from tree rings of pinyon pine (Pinus edulis) from Mummy Cave, Canyon de Chelly National Monument, Chinle, Arizona, USA, for the period AD 770–780. These data reconfirm the timing of M12 and show a small rise in Δ14C in AD 774 latewood. Allowing for the delay in lateral transfer of radiocarbon produced at high latitude, this suggests that 14C peak production occurred in late winter or spring of AD 774. Additionally, Δ14C decreased slightly in the earlywood of AD 775 and increased in the latewood of AD 775 to a higher level than that observed in AD 774.

The effect of cadmium on shoot apical meristems of barley

2006 ◽  
Vol 37 (6) ◽  
pp. 371-374 ◽  
Author(s):  
N. M. Kaznina ◽  
G. F. Laidinen ◽  
A. F. Titov
Keyword(s):  
Apical Meristems ◽  
Shoot Apical Meristems

The PINHEAD/ZWILLE gene acts pleiotropically in Arabidopsis development and has overlapping functions with the ARGONAUTE1 gene

Development ◽  
1999 ◽  
Vol 126 (3) ◽  
pp. 469-481 ◽  
Author(s):  
K. Lynn ◽  
A. Fernandez ◽  
M. Aida ◽  
J. Sedbrook ◽  
M. Tasaka ◽  
...  
Keyword(s):  
Expression Patterns ◽  
Bilateral Symmetry ◽  
Floral Organ ◽  
Axillary Shoot ◽  
Apical Meristems ◽  
Shoot Apical Meristems ◽  
Positional Identity ◽  
Competence Factor ◽  
High Level

Several lines of evidence indicate that the adaxial leaf domain possesses a unique competence to form shoot apical meristems. Factors required for this competence are expected to cause a defect in shoot apical meristem formation when inactivated and to be expressed or active preferentially in the adaxial leaf domain. PINHEAD, a member of a family of proteins that includes the translation factor eIF2C, is required for reliable formation of primary and axillary shoot apical meristems. In addition to high-level expression in the vasculature, we find that low-level PINHEAD expression defines a novel domain of positional identity in the plant. This domain consists of adaxial leaf primordia and the meristem. These findings suggest that the PINHEAD gene product may be a component of a hypothetical meristem forming competence factor. We also describe defects in floral organ number and shape, as well as aberrant embryo and ovule development associated with pinhead mutants, thus elaborating on the role of PINHEAD in Arabidopsis development. In addition, we find that embryos doubly mutant for PINHEAD and ARGONAUTE1, a related, ubiquitously expressed family member, fail to progress to bilateral symmetry and do not accumulate the SHOOT MERISTEMLESS protein. Therefore PINHEAD and ARGONAUTE1 together act to allow wild-type growth and gene expression patterns during embryogenesis.

scholarly journals Class I KNOX Is Related to Determinacy during the Leaf Development of the Fern Mickelia scandens (Dryopteridaceae)

2020 ◽  
Vol 21 (12) ◽  
pp. 4295 ◽  
Author(s):  
Rafael Cruz ◽  
Gladys F. A. Melo-de-Pinna ◽  
Alejandra Vasco ◽  
Jefferson Prado ◽  
Barbara A. Ambrose
Keyword(s):  
Leaf Development ◽  
Apical Meristem ◽  
Class I ◽  
Seed Plants ◽  
Histone H4 ◽  
Knox Genes ◽  
Apical Meristems ◽  
Cell Divisions ◽  
Shoot Apical Meristems

Unlike seed plants, ferns leaves are considered to be structures with delayed determinacy, with a leaf apical meristem similar to the shoot apical meristems. To better understand the meristematic organization during leaf development and determinacy control, we analyzed the cell divisions and expression of Class I KNOX genes in Mickelia scandens, a fern that produces larger leaves with more pinnae in its climbing form than in its terrestrial form. We performed anatomical, in situ hybridization, and qRT-PCR experiments with histone H4 (cell division marker) and Class I KNOX genes. We found that Class I KNOX genes are expressed in shoot apical meristems, leaf apical meristems, and pinnae primordia. During early development, cell divisions occur in the most distal regions of the analyzed structures, including pinnae, and are not restricted to apical cells. Fern leaves and pinnae bear apical meristems that may partially act as indeterminate shoots, supporting the hypothesis of homology between shoots and leaves. Class I KNOX expression is correlated with indeterminacy in the apex and leaf of ferns, suggesting a conserved function for these genes in euphyllophytes with compound leaves.

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