Ethylene, gibberellins, auxin and the apical control of branch angle in a conifer, Cupressus arizonica

Planta ◽  
1980 ◽  
Vol 148 (1) ◽  
pp. 64-68 ◽  
Author(s):  
T. J. Blake ◽  
R. P. Pharis ◽  
D. M. Reid
1998 ◽  
Vol 76 (11) ◽  
pp. 1852-1856 ◽  
Author(s):  
Brayton F Wilson

The results of three studies at different stages of branch development demonstrated the importance of apical control of diameter growth in both stem formation and branch angle. Diameter growth is controlled by competition between branches and the stem for branch-produced photosynthate. Apical control of branch angle occurs only in species that can produce differential growth stresses. In those species, upward bending is largely regulated by the amount of branch diameter growth. The first study followed stem formation from current shoots in Kalmia latifolia L., a shrub without terminal buds or apical control of branch angle. When several current or older shoots were competing, the longest, most distal lateral shoot usually became the stem. Shoot angle was poorly correlated with eventual dominance. A more proximal lateral shoot on the underside of a leaning parent became the longest, dominant lateral in 24% of the parent shoots. The second study used stem girdles to test the hypothesis that the subjacent stem competes with the branch for branch-produced photosynthate. Results from Pinus strobus L. supported the hypothesis, but results from Betula lenta L. and Acer rubrum L. did not. The third study removed apical control from branches of six forest-shrub species by cutting off the stem above the branch. Branches of all species increased diameter growth after cutting the stem, but only branches of Ilex verticillata (L.) Gray, Hamamelis virginiana L., and Cornus amomum Mill. developed differential growth stress and bent upward. Treated branches of Gaylusaccia baccata (Wang.) K. Koch, Viburnum cassinoides L., and K. latifolia sagged as much as controls.Key words: apical control, diameter growth, branch angle, growth stress, reaction wood.


2020 ◽  
Vol 55 ◽  
pp. 126841
Author(s):  
Zahra Babapour Aliyar ◽  
Abbas Banj Shafiei ◽  
Nasrin Seyedi ◽  
Salar Rezapour ◽  
Saeed Musavi Moghanjugi

1990 ◽  
Vol 43 (1-2) ◽  
pp. 37-45 ◽  
Author(s):  
I.R. Dann ◽  
P.D. Mitchell ◽  
P.H. Jerie
Keyword(s):  

1988 ◽  
Vol 66 (7) ◽  
pp. 1308-1315 ◽  
Author(s):  
David Garbary ◽  
Daniel Belliveau ◽  
Robert Irwin

Cell elongation in the Ceramiaceae typically occurs by means of one or two bands located apically and (or) basally in each cell. In axial cells of Antithamnion defectum two bands are present; however, most cell elongation occurs as a result of new wall deposition in bands at the base of each axial cell. In cells of determinate branches, only the basal band is present. In experimental conditions in which apical cells of indeterminate branches are differentially excised, location of the primary elongation band can be reestablished in relation to remaining indeterminate axes. Thus, the primary elongation band in axial cells is always basal with respect to indeterminate apical cells. When all indeterminate apices are removed, band growth becomes highly disrupted, and diffuse, irregularly located bands are formed. These results suggest that regulation of band position and elongation is through apical control.


2021 ◽  
Author(s):  
Sylvan Kaufman

Abstract At present, in the New World, C. arizonica and its varieties are of low economic importance, but they are sometimes cut for fenceposts, fuelwood and lumber, and recently they have become popular as Christmas trees. By contrast, the Arizona cypress (C. arizonica var. arizonica) and the smooth cypress (C. arizonica var. glabra) are widespread in Europe and are used for landscaping, erosion control, windbreaks, and to a minor extent for lumber.


2018 ◽  
Vol 48 (9) ◽  
Author(s):  
Lucas De Ross Marchioretto ◽  
Andrea De Rossi ◽  
Leonardo Oliboni do Amaral ◽  
Ana Maria Alves de Souza Ribeiro

ABSTRACT: Until few years ago there were limited options of apple rootstocks commercially available for Brazilian growers; although, new series of Geneva® rootstocks introduced recently present desirable features such as vigor control and wider lateral branch angle. On the main apple producing regions of Brazil, intermittent rainfall eventually occurs and waterlogged condition is frequent especially in high clay oxisols; in addition, little is known about the tolerance of rootstocks M.9, Marubakaido/M.9 interstock, G.202, G.213 and G.814 to waterlogging. Thus, the objective of this experiment was to evaluate the tolerance of these rootstocks to short-term waterlogging on root and aerial parameters. Potted ‘Maxi Gala’ apple plants were kept under 48 hours of waterlogging weekly throughout 19 weeks to be compared with a normal hydric condition control. The evaluated variables were: leaf, stem and root dry matter, number and length of new root emission, and number of leaves, mean leaf size and chlorophyll content. Rootstocks G.202, G.814 and Marubakaido/M.9 interstock presented more tolerance to waterlogging, and the main defense mechanism was the emission of new adventitious roots.


1995 ◽  
Vol 95 (4) ◽  
pp. 563-568 ◽  
Author(s):  
Marie Bollmark ◽  
Hao-Jie Chen ◽  
Thomas Moritz ◽  
Lennart Eliasson

2021 ◽  
Author(s):  
Álvaro Montesinos ◽  
Chris Dardick ◽  
María José Rubio-Cabetas ◽  
Jérôme Grimplet

Almond breeding programs aimed at selecting cultivars adapted to intensive orchards have recently focused on the optimization of tree architecture. This multifactorial trait is defined by numerous components controlled by processes such as hormonal responses, gravitropism and light perception. Gravitropism sensing is crucial to control the branch angle and therefore, the tree habit. A gene family, denominated IGT family after a share conserved domain, has been described as involved in the regulation of branch angle in several species, including rice and Arabidopsis, and even in fruit trees like peach. Here we identified six members of this family in almond: LAZY1 , LAZY2 , TAC1 , DRO1 , DRO2 , IGT-like . After analyzing their protein sequences in forty-one almond cultivars and wild species, little variability was found, pointing a high degree of conservation in this family. Gene expression was analyzed in fourteen cultivars of agronomical interest comprising diverse tree habit phenotypes. Only LAZY1 , LAZY2 and TAC1 were expressed in almond shoot tips during the growing season. No relation was established between the expression profile of these genes and the tree habit. However, some insight has been gained in how LAZY1 and LAZY2 are regulated, identifying the IPA1 almond homologues and other transcription factors involved in hormonal responses as regulators of their expression. Besides, we have found various polymorphisms that could not be discarded as involved in a potential polygenic origin of regulation of architectural phenotypes. Therefore, we have established that unlike many species, IGT family genes do not play a critical role in the control of tree habit in currently commercialized almond cultivars, with other gene families contributing to the variability of these traits.


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