scholarly journals Role for the shoot apical meristem in the specification of juvenile leaf identity in Arabidopsis

2019 ◽  
Vol 116 (20) ◽  
pp. 10168-10177 ◽  
Author(s):  
Jim P. Fouracre ◽  
R. Scott Poethig
Keyword(s):  
Transcription Factors ◽  
Phase Change ◽  
Plant Development ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Relative Importance ◽  
Genetic Pathway ◽  
Vegetative Phase ◽  
Vegetative Phase Change ◽  
Juvenile Leaf

The extent to which the shoot apical meristem (SAM) controls developmental decisions, rather than interpreting them, is a longstanding issue in plant development. Previous work suggests that vegetative phase change is regulated by signals intrinsic and extrinsic to the SAM, but the relative importance of these signals for this process is unknown. We investigated this question by examining the effect of meristem-deficient mutations on vegetative phase change and on the expression of key regulators of this process, miR156 and its targets, SPL transcription factors. We found that the precocious phenotypes of meristem-deficient mutants are a consequence of reduced miR156 accumulation. Tissue-specific manipulation of miR156 levels revealed that the SAM functions as an essential pool of miR156 early in shoot development, but that its effect on leaf identity declines with age. We also found that SPL genes control meristem size by repressing WUSCHEL expression via a novel genetic pathway.

scholarly journals ALTERED MERISTEM PROGRAM1 regulates leaf identity independent of miR156-mediated translational repression

2019 ◽  
Author(s):  
Jim P. Fouracre ◽  
Victoria J. Chen ◽  
R. Scott Poethig
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Phase Change ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Translational Repression ◽  
Transcript Levels ◽  
Vegetative Phase Change ◽  
Squamosa Promoter Binding Protein ◽  
Summary Statement

AbstractIn Arabidopsis, loss of the carboxypeptidase, ALTERED MERISTEM PROGRAM1 (AMP1), produces an increase in the rate of leaf initiation, an enlarged shoot apical meristem and an increase in the number of juvenile leaves. This phenotype is also observed in plants with reduced levels of miR156-targeted SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) transcription factors, suggesting that AMP1 may promote SPL activity. However, we found that the amp1 phenotype is only partially corrected by elevated SPL gene expression, and that amp1 has no significant effect on SPL transcript levels, or on the level or the activity of miR156. Although evidence from a previous study suggests that AMP1 promotes miRNA-mediated translational repression, amp1 did not prevent the translational repression of the miR156 target, SPL9, or the miR159 target, MYB33. These results suggest that AMP1 regulates vegetative phase change downstream of, or in parallel to, the miR156/SPL pathway and that it is not universally required for miRNA-mediated translational repression.Summary statementWe show that loss of the carboxypeptidase, AMP1, does not interfere with the function of miR156 or miR159, suggesting that AMP1 is not universally required for miRNA-mediated translational repression in Arabidopsis.

scholarly journals VAL genes regulate vegetative phase change via miR156-dependent and independent mechanisms

2021 ◽  
Author(s):  
Jim P. Fouracre ◽  
Jia He ◽  
Victoria J. Chen ◽  
Simone Sidoli ◽  
R. Scott Poethig
Keyword(s):  
Transcription Factors ◽  
Phase Change ◽  
Temporal Dynamics ◽  
Epigenetic Silencing ◽  
Developmental Transitions ◽  
Vegetative Phase ◽  
Vegetative Phase Change ◽  
Adult Growth ◽  
Epigenetic Repression ◽  
Polycomb Repressive Complex 1

SummaryHow organisms control when to transition between different stages of development is a key question in biology. In plants, epigenetic silencing by Polycomb repressive complex 1 (PRC1) and PRC2 plays a crucial role in promoting developmental transitions, including from juvenile-to-adult phases of vegetative growth. It is well established that PRC1/2 repress the master regulator of vegetative phase change, miR156, leading to the transition to adult growth, but how this process in temporally regulated is unknown. Here we investigate whether transcription factors in the VIVIPAROUS/ABI3-LIKE (VAL) gene family provide the temporal signal for the epigenetic repression of miR156. Exploiting a novel val1 allele, we found that VAL1 and VAL2 redundantly regulate vegetative phase change by controlling the overall level, rather than temporal dynamics, of miR156 expression. Furthermore, we discovered that VAL1 and VAL2 also act independently of miR156 to control this important developmental transition.

scholarly journals Physiological, Epigenetic, and Genetic Regulation of Vegetative Phase Change and Rejuvenation in Plants

2021 ◽  
Author(s):  
Tajbir Raihan ◽  
Robert L. Geneve ◽  
Sharyn E. Perry ◽  
Carlos M. Rodriguez Lopez
Keyword(s):  
Gene Expression ◽  
Phase Transitions ◽  
Phase Change ◽  
Plant Development ◽  
Genetic Regulation ◽  
Environmental Cues ◽  
Climate Change Scenarios ◽  
Epigenetic Factors ◽  
Vegetative Phase ◽  
Vegetative Phase Change

In contrast to animals, adult organs in plants are not determined during embryogenesis but gen-erated from meristematic cells as plants advance through development. Plant development in-volves a succession of different phenotypic stages and the transition between these stages is termed phase transition. Phase transitions need to be tightly regulated and coordinated to ensure they occur under optimal seasonal, environmental conditions. Polycarpic perennials transition through vegetative stages and the mature, reproductive stage many times during their lifecycles and, in both perennial and annual species, environmental factors and culturing methods can re-verse the otherwise unidirectional vector of plant development. Epigenetic factors regulating gene expression in response to internal cues and external (environmental) stimuli influencing the plant’s phenotype and development have been shown to control phase transitions. How develop-mental and environmental cues interact to epigenetically alter gene expression and influence these transitions are not well understood and understanding this interaction is important considering the current climate change scenarios, since epigenetic maladaptation could have catastrophic con-sequences for perennial plants in natural and agricultural ecosystems. Here we review studies focussing on the epigenetic regulators of the vegetative phase change and highlight how these mechanisms might act in exogenously induced plant rejuvenation and regrowth following stress.

Genetic Control of Reproductive and Vegetative Phase Change in the Eucalyptus risdonii - E. tenuiramis Complex

1998 ◽  
Vol 46 (1) ◽  
pp. 45 ◽  
Author(s):  
R. J. E. Wiltshire ◽  
J. B. Reid ◽  
B. M. Potts
Keyword(s):  
Phase Change ◽  
Genetic Basis ◽  
Natural Populations ◽  
Phase Changes ◽  
Common Environment ◽  
Vegetative Phase ◽  
Precocious Flowering ◽  
Vegetative Phase Change ◽  
Juvenile Leaf ◽  
Independent Variation

Eucalyptus risdonii Hook.f. is believed to be a juvenilised form of its sister species, E. tenuiramis Miq., differing largely in the retention of the juvenile leaf type at reproductive maturity. The genetic basis of this ontogenetic variation was examined by monitoring reproductive and vegetative phase changes in 1201 open-pollinated progeny from 40 E. risdonii–E. tenuiramis populations in a field trial over 6 years. Vegetative and reproductive phase changes were highly heritable and genetically independent within populations. Estimates of individual narrow-sense heritabilities for height and timing of vegetative phase change ranged from 0.46–0.67 and 0.19–0.23 respectively, and for time of first flowering from 0.31–0.41. Variation in the height of vegetative phase change amongst progeny grown in a common environment was very similar to that observed in the natural populations from different environments, demonstrating a genetic basis to a stepped cline in the retention of the juvenile leaf form (neoteny). However, a separate pattern of variability in the time to flowering was evident, with precocious flowering found in a number of phenetic groups. This independent variation of reproductive and vegetative phase changes may allow dramatic heterochronic alterations in morphology and physiology with minimal genetic change. The continuous nature of the neotenic variation suggests that speciation by this mode of evolution is not yet complete in the E. risdonii–E. tenuiramis complex, but has presumably operated to produce many other neotenous eucalypt species.

scholarly journals Sugar promotes vegetative phase change in Arabidopsis thaliana by repressing the expression of MIR156A and MIR156C

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Li Yang ◽  
Mingli Xu ◽  
Yeonjong Koo ◽  
Jia He ◽  
R Scott Poethig
Keyword(s):  
Arabidopsis Thaliana ◽  
Phase Change ◽  
Nutrient Availability ◽  
Developmental Timing ◽  
Vegetative Phase ◽  
Adult Transition ◽  
Vegetative Phase Change ◽  
Exogenous Glucose ◽  
Exogenous Sugar ◽  
Signaling Activity

Nutrients shape the growth, maturation, and aging of plants and animals. In plants, the juvenile to adult transition (vegetative phase change) is initiated by a decrease in miR156. In Arabidopsis, we found that exogenous sugar decreased the abundance of miR156, whereas reduced photosynthesis increased the level of this miRNA. This effect was correlated with a change in the timing of vegetative phase change, and was primarily attributable to a change in the expression of two genes, MIR156A and MIR156C, which were found to play dominant roles in this transition. The glucose-induced repression of miR156 was dependent on the signaling activity of HEXOKINASE1. We also show that the defoliation-induced increase in miR156 levels can be suppressed by exogenous glucose. These results provide a molecular link between nutrient availability and developmental timing in plants, and suggest that sugar is a component of the leaf signal that mediates vegetative phase change.

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