The transition from spiral to distichous leaf arrangement during gibberellic-acid (GA3)-induced rejuvenation in Hedera was studied in detail by scanning electron microscopy of the shoot apical meristem. The transition, which involves the initiation of about 14 new leaf primordia, is accomplished by progressive increments in the divergence angle between the leaf primordia from an initial average value of 138.9 ° until it approaches 180 °. This process is preceded, as well as accompanied, by an increased radial displacement of young leaf primordia away from the apical meristem. Although the width of the leaf primordia also increases, this is unlikely to be a causal factor since it occurs only late in the transition. The size of the primordium-free area of the apical meristem is also unlikely to be involved. Quantitative analysis shows that the divergence angle of consecutive leaf primordia commonly fluctuates between relatively large and small values. Thus the transitional stages form a spirodistichous arrangement in which the divergence angle within each pair of leaves is large relative to that between leaf pairs. The stimulation of the radial displacement of the leaf primordia and the associated phyllotactic transition may involve GA3-induced modification in the spatial organization of cortical microtubules in the apical meristem and related changes in directional cell expansion.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1007/BF00194058 | DOI Listing |
Ann Bot
December 2024
Laboratório de Anatomia Vegetal (LAVeg), Federal University of Rio Grande do Sul, Av. Bento Gonçalves, 9500, Porto Alegre, RS, Brazil.
Background And Aims: Recent studies have documented numerous morphoanatomical variations for the seed coat in Bromeliaceae. However, the structural diversity and character evolution of the embryo within this family remain largely unexplored. Given the embryo's significance in plant diversification, this research aims to investigate the morphology and key anatomical features of Bromeliaceae embryos, providing insights into character evolution, taxonomic applications, and reproductive biology.
View Article and Find Full Text PDFPlants (Basel)
December 2024
School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
The reduction of leaves was a key event in the evolution of the succulent syndrome in Cactaceae, evolving from large, photosynthetic leaves in to nearly suppressed microscopic foliar buds in succulent . This leaf reduction was accompanied by the development of spines. Early histological studies, dating back a century, of the shoot apical meristem (SAM) in several species concluded that, in succulent cacti, axillary buds became areoles and leaves transformed into spines.
View Article and Find Full Text PDFNew Phytol
December 2024
Departamento de Ciências Biológicas, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, SP, 13418-900, Brazil.
Front Plant Sci
November 2024
Institute of Plasma Technology, Korea Institute of Fusion Energy, Gunsan, Republic of Korea.
Introduction: Recent advancements in agricultural technology have highlighted the potential of eco-friendly innovations, such as plasma-activated water (PAW), for enhancing seed germination, growth, and biomass production.
Methods: In this study, we investigated the effects of PAW irrigation on young sorghum seedlings through phenotypic and transcriptional analyses. We measured growth parameters, including seedling height, stem thickness, and biomass, across five sorghum varieties: BTx623, Sodamchal, Noeulchal, Baremae, and Hichal.
Plant Dis
October 2024
Wuhan Academy of Agriculture Science, Institute of Crop Science, Wuhan, Hubei , China;
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!