7. The role of plant growth regulators in forest tree cambial growth

Little, C. H. A.; Savidge, Rodney Arthur

doi:10.1007/bf00043953

Cited by 110 publications

(9 citation statements)

References 180 publications

(190 reference statements)

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“…Cambial meristematic activity, shorter enlarging time of tracheid and the number of wall layers produced [58,80] may have played a more important role. A reduction in crown growth or LAI during drought could signal a reduction in cambial growth via lower indole-3-acetic acid (IAA) production [10]. Given future climate change scenarios, we could anticipate a continued coexistence of both species at this site and region under current levels of drought stress with a competition advantage for P. nigra given its faster growth and more flexible xylem development.…”

Section: Intrinsic Water-use Efficiencymentioning

confidence: 99%

Effects of Drought on Xylem Anatomy and Water-Use Efficiency of Two Co-Occurring Pine Species

Martín-Benito

Anchukaitis

Evans

et al. 2017

Forests

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Exploring how drought influences growth, performance, and survival in different species is crucial to understanding the impacts of climate change on forest ecosystems. Here, we investigate the responses of two co-occurring pines (Pinus nigra and Pinus sylvestris) to interannual drought in east-central Spain by dendrochronological and wood anatomical features integrated with isotopic ratios of carbon (δ 13 C) and oxygen (δ 18 O) in tree rings. Our results showed that drought induces both species to allocate less carbon to build tracheid cell-walls but increases tracheid lumen diameters, particularly in the transition wood between early and latewood, potentially maximizing hydraulic conductivity but reducing resistance to embolism at a critical phase during the growing season. The thicker cell-wall-to-lumen ratio in P. nigra could imply that its xylem may be more resistant to bending stress and drought-induced cavitation than P. sylvestris. In contrast, the higher intrinsic water-use efficiency (iWUE) in P. sylvestris suggests that it relies more on a water-saving strategy. Our results suggest that narrower cell-walls and reduced growth under drought are not necessarily linked to increased iWUE. At our site P. nigra showed a higher growth plasticity, grew faster and was more competitive than P. sylvestris. In the long term, these sustained differences in iWUE and anatomical characters could affect forest species performance and composition, particularly under increased drought stress.

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Section: Intrinsic Water-use Efficiencymentioning

confidence: 99%

Effects of Drought on Xylem Anatomy and Water-Use Efficiency of Two Co-Occurring Pine Species

Martín-Benito

Anchukaitis

Evans

et al. 2017

Forests

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“…Earlier studies had shown that indole-3-acetic acid (IAA) plays an important role in cambial activity and wood formation of woody plants [11,12]. Since then, numerous experiments using exogenous auxin treatments of both hardwoods and conifers have demonstrated the potential of IAA to affect most aspects of cambial growth in a dose-dependent manner, including xylem and phloem production and size, as well as secondary wall thickness of xylem elements [13,14,15,16]. Gibberellins (GAs) are also important regulators of stem growth and wood formation and considerable evidence demonstrates that exogenous application of gibberellic acid (GA 3 ) promotes cambial cell division, expansion of cambium derivatives and tension wood formation [5,17,18,19].…”

Section: Introductionmentioning

confidence: 99%

Exogenous Application of Phytohormones Promotes Growth and Regulates Expression of Wood Formation-Related Genes in Populus simonii × P. nigra

Yuan

Zhao

Guo

et al. 2019

IJMS

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Although phytohormones are known to be important signal molecules involved in wood formation, their roles are still largely unclear. Here, Populus simonii × P. nigra seedlings were treated with different concentrations of exogenous phytohormones, indole-3-acetic acid (IAA), gibberellin (GA3), and brassinosteroid (BR), and the effects of phytohormones on growth were investigated. Next, 27 genes with known roles in wood formation were selected for qPCR analysis to determine tissue-specificity and timing of responses to phytohormone treatments. Compared to the control, most IAA, GA3, and BR concentrations significantly increased seedling height. Meanwhile, IAA induced significant seedling stem diameter and cellulose content increases that peaked at 3 and 30 mg·L−1, respectively. Significant increase in cellulose content was also observed in seedlings treated with 100 mg·L−1 GA3. Neither stem diameter nor cellulose content of seedlings were affected by BR treatment significantly, although slight effects were observed. Anatomical measurements demonstrated improved xylem, but not phloem, development in IAA- and BR-treated seedlings. Most gene expression patterns induced by IAA, GA3, and BR differed among tissues. Many IAA response genes were also regulated by GA3, while BR-induced transcription was weaker and slower in Populus than for IAA and GA3. These results reveal the roles played by phytohormones in plant growth and lay the foundation for exploring molecular regulatory mechanisms of wood formation in Populus.

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“…In contrast, latewood (LW) tracheids start forming at times when the intensity of IAA supply to cambium is reduced and the formation of annual shoots has ended. LW tissues have smaller radial dimensions, but thicker cell walls (Little & Savidge 1987), and, forming at the time of reduced IAA concentration, have smaller radial dimensions; on the other hand, they have more time for differentiation and are much more intensely supplied with assimilates from already-formed annual shoots for the creation of their secondary walls, which gives them their typical thick-walled structures (Sundberg et al 1987. According to Larson (1969), the formation of LW occurs when the concentration of IAA is gradually reduced and carbohydrate contents rise.…”

Section: Introductionmentioning

confidence: 99%

Auxin (IAA) and soluble carbohydrate seasonal dynamics monitored during xylogenesis and phloemogenesis in Scots pine

Fajstavr¹,

Paschová²,

Giagli³

et al. 2018

iForest

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Biogeosciences and Forestry Biogeosciences and Forestry Auxin (IAA) and soluble carbohydrate seasonal dynamics monitored during xylogenesis and phloemogenesis in Scots pineMarek Fajstavr (1-2) , Zuzana Paschová (1) , Kyriaki Giagli (1) , Hanuš Vavrčík (1) , Vladimír Gryc (1) , Josef Urban (3)(4) The metabolic activity of phytohormones and the accumulation of carbohydrates affect the reactivation of the cambial zone and the radial increment of woody plants. We aimed to monitor the dynamics of indole-3-acetic acid (IAA) concentration and amounts of soluble carbohydrates during xylem and phloem formation of one growing season (2015). Six sample trees of Scots pine (Pinus sylvestris L.), aged 80 years on average, growing in the Sobešice research site (404 m a.s.l.) in the Czech Republic were selected. We obtained microcore samples at weekly intervals by the Trephor tool method for cell formation analysis and spectrophotometric determination of IAA and soluble carbohydrate contents. We found that time of the highest concentration of IAA (last week of April) coincided with time of the maximum number of cells in the cambial zone and highest expansion of the cell enlargement stage. When the IAA concentration was too low to be measured, latewood tracheids started to form, and late phloem sieve cell formation ceased. The highest concentration of soluble carbohydrates was 200.40 ± 21.6 µg GLU per sample (May 14). This coincided with the fastest weekly xylem cell increment. This research shows that IAA and soluble carbohydrate dynamics directly affects xylem and phloem formation.

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7. The role of plant growth regulators in forest tree cambial growth

Cited by 110 publications

References 180 publications

Effects of Drought on Xylem Anatomy and Water-Use Efficiency of Two Co-Occurring Pine Species

Effects of Drought on Xylem Anatomy and Water-Use Efficiency of Two Co-Occurring Pine Species

Exogenous Application of Phytohormones Promotes Growth and Regulates Expression of Wood Formation-Related Genes in Populus simonii × P. nigra

Auxin (IAA) and soluble carbohydrate seasonal dynamics monitored during xylogenesis and phloemogenesis in Scots pine

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