scholarly journals Quantitative genetic evidence that the timing of vegetative phase change in Eucalyptus globulus ssp. globulus is an adaptive trait

2000 ◽  
Vol 48 (5) ◽  
pp. 561 ◽  
Author(s):  
Gregory J. Jordan ◽  
Bradley M. Potts ◽  
Paula Chalmers ◽  
Robert J. E. Wiltshire
Keyword(s):  
Phase Change ◽  
Early Phase ◽  
Eucalyptus Globulus ◽  
Field Trials ◽  
Vegetative Phase ◽  
Precocious Flowering ◽  
Vegetative Phase Change ◽  
Quantitative Genetic ◽  
Current Selection ◽  
Broad Scale

Quantitative genetic analysis of six field trials suggests a complex pattern of adaptive significance for the timing of the abrupt change in leaf form in Eucalyptus globulus Labill. spp. globulus. Data from one small trial demonstrated a genetic basis to a steep local cline in habit, in the size of plants flowering and in the height of the change in foliage type. Thus, slow growth, early phase change and precocious flowering appear to be maintained in exposed coastal environments by current selection. This contrasts with results from five large trials that contained open-pollinated progeny from across the whole geographic range of this taxon. On this broad scale, early phase change appears to promote growth, a fitness surrogate, in two trials but not the others, implying differential selection for the timing of phase change. In these cases, early phase change may have been favoured in warm, wet environments by reducing damage by leaf fungi. There was marked genetic variation in the timing of vegetative phase change among broad regions, consistent with either adaptation to broad-scale environmental variation or historical differentiation.

Susceptibility to Teratosphaeria nubilosa and precocity of vegetative phase change in Eucalyptus globulus and E. maidenii (Myrtaceae)

2013 ◽  
Vol 61 (8) ◽  
pp. 583 ◽  
Author(s):  
Gustavo Balmelli ◽  
Sofía Simeto ◽  
Diego Torres ◽  
Alicia Castillo ◽  
Nora Altier ◽  
...  
Keyword(s):  
Genetic Variation ◽  
High Risk ◽  
Phase Change ◽  
Eucalyptus Globulus ◽  
Damage Index ◽  
Genetic Stock ◽  
Vegetative Phase ◽  
Vegetative Phase Change ◽  
Leaf Spots ◽  
Late Transition

Since the first report of Teratosphaeria nubilosa (Cooke) Crous & U.Braun in Uruguay in 2007, young plantations of Eucalyptus globulus Labill. and E. maidenii F.Muell. have been severely damaged by Mycosphaerella leaf disease. The genetic variation in disease resistance and in the timing of heteroblastic phase change was examined in 194 open-pollinated families of E. globulus and 86 families of E. maidenii growing in a field trial in south-eastern Uruguay, naturally infected by T. nubilosa. Disease severity, precocity of vegetative phase change and tree growth were assessed at 14 months. E. globulus was significantly more susceptible to T. nubilosa than was E. maidenii, presenting higher severity of leaf spots (10.6% and 5.6%, respectively), higher defoliation (31.9% and 22.9%, respectively) and higher crown-damage index (39.1% and 27.4%, respectively). However, the heteroblastic transition began significantly earlier in E. globulus than in E. maidenii, with 34.1% and 2.8% of the trees having some proportion of their crown with adult foliage at 14 months, respectively. Significant individual narrow-sense heritabilities were found in E. globulus for severity of leaf spots (0.40), defoliation (0.24), crown-damage index (0.30) and proportion of adult foliage (0.64). Additive genetic variation in E. maidenii was significant only for defoliation and crown-damage index, with a moderate heritability (0.21 and 0.20, respectively). Although E. maidenii was more resistant to T. nubilosa than was E. globulus, the degree of resistance was not enough to consider this species as an alternative to E. globulus for high-risk disease sites. In addition, the small genetic variability for resistance on the juvenile foliage and the late transition to adult foliage suggested that the chances for early selection in E. maidenii are quite limited. By contrast, the genetic variation in E. globulus clearly indicated that through selection for resistance of the juvenile foliage, and especially by selecting for early phase change, it is possible to obtain genetic stock suitable for sites with high risk of T. nubilosa infection.

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.

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.

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