scholarly journals The HK5 and HK6 cytokinin receptors mediate diverse developmental pathways in rice

Development ◽  
2020 ◽  
Vol 147 (20) ◽  
pp. dev191734
Author(s):  
Christian A. Burr ◽  
Jinjing Sun ◽  
Maria V. Yamburenko ◽  
Andrew Willoughby ◽  
Charles Hodgens ◽  
...  
Keyword(s):  
Growth And Development ◽  
Apical Meristem ◽  
Shoot Growth ◽  
Floral Development ◽  
Developmental Pathways ◽  
Cytokinin Signaling ◽  
Cytokinin Receptors ◽  
Root And Shoot Growth ◽  
Cytokinin Response

ABSTRACTThe phytohormone cytokinin regulates diverse aspects of plant growth and development. Our understanding of the metabolism and perception of cytokinin has made great strides in recent years, mostly from studies of the model dicot Arabidopsis. Here, we employed a CRISPR/Cas9-based approach to disrupt a subset of cytokinin histidine kinase (HK) receptors in rice (Oryza sativa) in order to explore the role of cytokinin in a monocot species. In hk5 and hk6 single mutants, the root growth, leaf width, inflorescence architecture and/or floral development were affected. The double hk5 hk6 mutant showed more substantial defects, including severely reduced root and shoot growth, a smaller shoot apical meristem, and an enlarged root cap. Flowering was delayed in the hk5 hk6 mutant and the panicle was significantly reduced in size and infertile due to multiple defects in floral development. The hk5 hk6 mutant also exhibited a severely reduced cytokinin response, consistent with the developmental phenotypes arising from a defect in cytokinin signaling. These results indicate that HK5 and HK6 act as cytokinin receptors, with overlapping functions to regulate diverse aspects of rice growth and development.

GROWTH AND DEVELOPMENT OF THE LOWBUSH BLUEBERRY: APICAL ABORTION

1963 ◽  
Vol 41 (9) ◽  
pp. 1319-1324 ◽  
Author(s):  
W. G. Barker ◽  
W. B. Collins
Keyword(s):  
Vegetative Growth ◽  
Growth And Development ◽  
Apical Meristem ◽  
Shoot Growth ◽  
Strong Indication ◽  
Vegetative Tissue ◽  
Aerial Shoot ◽  
Lowbush Blueberry ◽  
Below Ground ◽  
High Level

The semicultivated lowbush blueberry is fire-pruned on a 3- to 4-year cycle. In spring, vegetative growth is accomplished through the development of an axillary bud on an aerial shoot. In a fire-pruned area, the growth is delayed in both its initiation and termination by as much as a month and arises either from axillary buds on the unburned below-ground portions of the aerial stems, or from rhizome seated buds. Shoot growth is terminated by the abortion of the apical meristem and the death of the proximal portions of the axis. Evidence is presented suggesting that the death of the apex is not triggered by an appropriate photoperiod. Further, although it is inherently controlled, it does not follow the production of a specified quantity (relative to clone) of leaf nor vegetative tissue and is not related to the development of a specified (per clone) leaf photosynthetic area. Finally, there is a strong indication that the death of the shoot is speeded by the presence of a high level of auxin.

Involvement of Abscisic Acid in Controlling Plant Growth in Soil of Low Water Potential

1993 ◽  
Vol 20 (5) ◽  
pp. 425 ◽  
Author(s):  
R Munns ◽  
RE Sharp
Keyword(s):  
Abscisic Acid ◽  
Plant Growth ◽  
Water Potential ◽  
Cell Expansion ◽  
Shoot Growth ◽  
Xylem Sap ◽  
Leaf Expansion ◽  
Root And Shoot Growth ◽  
Dry Soil

Hormones appear to be important in controlling plant growth in soils of low water potential, particularly in changing the root:shoot ratio as the soil dries or becomes saline, and in communicating soil conditions to the leaves. This review has necessarily focused on abscisic acid (ABA), as there is little information about the role of other hormones in controlling growth in dry or saline soils. ABA is partly responsible for the differential response of root and shoot growth to dry soils. In dry soil it maintains root growth and inhibits shoot growth. However, when applied to well-watered plants, it usually inhibits root and shoot growth, showing that plants in dry soil respond quite differently from well-watered plants. ABA affects the rate of cell expansion in plants in dry soils: it maintains cell expansion in roots and inhibits that in leaves. It may also affect the rate of cell production, but little is known about this. The role of ABA as a long-distance signal in controlling growth by root-to-shoot communication is unclear: the concentrations found in xylem sap can affect stomatal conductance, but seem too low to affect leaf expansion. Yet drought and salinity generally affect leaf expansion before they affect leaf conductance. A possible solution to this puzzle is that ABA is transported in xylem sap in a complexed form, or that another compound in xylem sap stimulates the synthesis or activity of ABA in leaves, or affects leaf expansion independently of ABA.

scholarly journals The cytokinin response factors modulate root and shoot growth and promote leaf senescence in Arabidopsis

2015 ◽  
Vol 85 (1) ◽  
pp. 134-147 ◽  
Author(s):  
Tracy Raines ◽  
Carly Shanks ◽  
Chia-Yi Cheng ◽  
Duncan McPherson ◽  
Cristiana T. Argueso ◽  
...  
Keyword(s):  
Leaf Senescence ◽  
Shoot Growth ◽  
Response Factors ◽  
Root And Shoot Growth ◽  
Cytokinin Response

scholarly journals The Mobile bypass Signal Arrests Shoot Growth by Disrupting Shoot Apical Meristem Maintenance, Cytokinin Signaling, and WUS Transcription Factor Expression

2016 ◽  
Vol 171 (3) ◽  
pp. 2178-2190 ◽  
Author(s):  
Dong-Keun Lee ◽  
David L. Parrott ◽  
Emma Adhikari ◽  
Nisa Fraser ◽  
Leslie E. Sieburth
Keyword(s):  
Transcription Factor ◽  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Shoot Growth ◽  
Cytokinin Signaling ◽  
Factor Expression ◽  
Meristem Maintenance ◽  
Transcription Factor Expression

Root growth and root growth capacity of white spruce (Piceaglauca (Moench) Voss) seedlings

1985 ◽  
Vol 15 (4) ◽  
pp. 625-630 ◽  
Author(s):  
Anne M. Johnson-Flanagan ◽  
John N. Owens
Keyword(s):  
Root Growth ◽  
Root Elongation ◽  
Shoot Growth ◽  
Lateral Roots ◽  
White Spruce ◽  
Shoot Elongation ◽  
Growth Capacity ◽  
Root Growth Capacity ◽  
Root And Shoot Growth

Root growth in the root systems of Styroplug-grown white spruce (Piceaglauca (Moench) Voss) seedlings increases in the spring before shoot elongation and again in the fall after bud development is complete. This is followed by root dormancy and quiescence, which are distinguished on the basis of ability to elongate under root growth capacity (RGC) conditions. The number of white long lateral roots produced during RGC tests correlated significantly with the number of white long lateral roots under lathhouse conditions. Increased mitotic activity is required for root elongation. However, mitotic frequencies could not be used to assess RGC because of the confounding effects of independent growth cycles in individual roots. Cell expansion and transformation of insoluble carbohydrates are important controls of root elongation. The relationship between root and shoot growth under RGC conditions may not support the role of shoot elongation in decreasing root elongation. Conversely, this may indicate that RGC tests alter the endogenous controls of root and shoot growth.

scholarly journals Making a mark: the role of RNA modifications in plant biology

2020 ◽  
Vol 42 (4) ◽  
pp. 26-30
Author(s):  
Matthew T. Parker ◽  
Katarzyna Knop ◽  
Gordon G. Simpson
Keyword(s):  
Messenger Rna ◽  
Growth And Development ◽  
Regulatory Networks ◽  
Molecular Mechanisms ◽  
Biological Significance ◽  
Plant Biology ◽  
Developmental Pathways ◽  
Rna Modifications ◽  
Feature Article

Plants coordinate their growth and development through complex regulatory networks involving changes in the expression of thousands of genes. Many developmental pathways are regulated at the level of messenger RNA (mRNA) through alternative choices in mRNA processing. These choices can have consequences for the localization, stability or translatability of mRNAs. One of the key ways in which RNAs are processed is by the methylation of the RNA base adenosine – a modification known as m6A. Even though it was first discovered in the 1970s, the biological significance of m6A marks has only recently become clear. In this feature article, we identify the factors controlling the writing and reading of m6A modifications in plants. We also highlight some of the features of plant development that depend on m6A and explore the recently discovered molecular mechanisms that use m6A to control development or response to environmental stress.

scholarly journals Growth of Rooted `Gala' Apple Microcuttings ex Vitro as Influenced by Initial Adventitious Root Count

HortScience ◽  
1993 ◽  
Vol 28 (6) ◽  
pp. 664-666 ◽  
Author(s):  
Dennis P. Stimart ◽  
James F. Harbage
Keyword(s):  
Adventitious Root ◽  
Significant Interaction ◽  
Adventitious Roots ◽  
Shoot Growth ◽  
Ex Vitro ◽  
Subsequent Growth ◽  
Root And Shoot Growth ◽  
Main Effects

The role of the number of adventitious roots of Malus domestics Borkh. `Gala' microcuttings in vitro on ex vitro root and shoot growth was investigated. Root initiation treatments consisted of IBA at 0, 0.15, 1.5, 15, and 150 μm in factorial combination with media at pH 5.5, 6.3, and 7.0. IBA concentrations significantly influenced final root count and shoot fresh and dry weights, but not plant height, leaf count, or root fresh and dry weights at 116 days. Between 0 and 0.15 μm IBA, final root counts were similar, but at 1.5, 15, and 150 μm IBA, root counts increased by 45%, 141%, and 159%, respectively, over the control. The pH levels did not affect observed characteristics significantly. There was no significant interaction between main effects. A significant positive linear relationship was found between initial and final root count. The results suggest a limited association between high initial adventitious root count and subsequent growth. Chemical name used: 1 H -indole-3-butyric acid (IBA).

The role of floral development in studies of legume evolution

1992 ◽  
Vol 70 (4) ◽  
pp. 692-700 ◽  
Author(s):  
Shirley C. Tucker
Keyword(s):  
Key Words ◽  
Floral Development ◽  
Developmental Pathways ◽  
Ceratonia Siliqua ◽  
Unique Type ◽  
Varied Structure ◽  
Interspecific Differences ◽  
Naturally Occurring ◽  
Key Words Development

Comparative floral development is useful to test hypotheses of phylogeny and taxonomic relationships among legumes because it provides a greater understanding of character states. It can reveal homologies, as in the cupule, an anomalous and varied structure among species of Psoralea that originates by fusion of two or more small bracts. Convergence is demonstrated by comparing differing developmental pathways of specialized floral features such as dorsiventral heterostameny, eccentric corolla, porate stamens, and enantiostyly, among species of Cassia, Senna, and Chamaecrista. Naturally occurring homeosis can be identified, as in the example of stamens developing from uncommitted primordia in petal sites in Saraca declinata. Floral development among species in a genus is generally very similar, with any differences usually occurring only terminally. In contrast, ontogenies among related genera show more differences, and those differences may be accelerated, appearing earlier in ontogeny than interspecific differences. Floral development in Ceratonia siliqua, in the same tribe as the Cassia group, diverges strongly from the latter, lacking petals and having a unique type of inception of stamens. Developmental evidence supports removing Ceratonia from Cassieae. Key words: development, evolution, flower, legumes, ontogeny, phylogeny.

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