Effect of naphthaleneacetic acid on the formation of lateral roots in the adventitious root of Allium cepa: number and arrangement of laterals along the parent root

1992 ◽  
Vol 70 (9) ◽  
pp. 1891-1896 ◽  
Author(s):  
Pedro G. Lloret ◽  
Antonio Pulgarín
Keyword(s):  
Allium Cepa ◽  
Adventitious Root ◽  
Lateral Root ◽  
Root Formation ◽  
Lateral Roots ◽  
Naphthaleneacetic Acid ◽  
Root Primordia ◽  
Sharp Rise ◽  
Allium Cepa L ◽  
Do So

The exogenous application of an auxin (α-naphthaleneacetic acid) to the adventitious root of Allium cepa L. promotes lateral root formation and inhibits main root elongation. If the adventitious roots are released from the influence of this auxin, they may resume elongation after 10−5 M but not after 10−4 treatment. Auxin leads to the appearance of late-forming root primordia intercalated between previously formed laterals. The arrangement of laterals along the adventitious root is another feature altered by treatment, i.e., control roots develop the same number of laterals throughout the length of the zone in which laterals appear, whereas in treated roots the number of laterals rises steadily as the distal end of this zone is approached. In 10−5 M auxin-treated roots, no increase in the number of laterals occurs in basal zones of the parent root, whereas treatment with 10−4 M naphthaleneacetic acid leads to a sharp rise in the number of laterals formed at these zones. Our results suggest that the basal part of onion roots is less sensitive than the apical portion of the effects of naphthaleneacetic acid. This chemical seems to have a rejuvenating effect on cells of the pericycle, enabling them to initiate lateral primordia when under normal conditions they would no do so. Key words: Allium cepa, auxin, lateral root, naphthaleneacetic acid, onion.

Effects of drought and subsequent rehydration on the structure, vitality, and permeability of Allium cepa adventitious roots

1993 ◽  
Vol 71 (5) ◽  
pp. 700-707 ◽  
Author(s):  
Elida Stasovski ◽  
Carol A. Peterson
Keyword(s):  
Allium Cepa ◽  
Lateral Root ◽  
Adventitious Roots ◽  
Free Water ◽  
Food Storage ◽  
Root Primordia ◽  
Root Cortex ◽  
Lateral Root Primordia ◽  
Allium Cepa L ◽  
Suberin Lamellae

Drought stress was induced in onion (Allium cepa L.) plants that had been sprouted from bulbs initially planted in moist vermiculite. The medium received no further water, and its free water content fell from 50 to 0% over a period of 35 d. The water stress thus imposed killed the root apices and accelerated the death of the epidermis. However, other regions, including the short cells of the dimorphic exodermis, the remainder of the cortex, and the stele (except for the mature vessels), remained alive for periods of prolonged drought (up to 200 d after cessation of watering). During this time, symplasmic continuity from the exodermis to the vascular tissues of the stele was maintained through the living cells as judged by the transport of fluorescein from an ambient solution into the stele. After the death of the epidermis, the presence of Casparian bands in all cells of the exodermis and suberin lamellae in its long cells presumably reduced the flow of water from the root to the dry external medium. A dieback pattern in which the cortex is retained would place an increased respiratory demand on the plant compared with dieback to the endodermis. However, this may be offset by positive functions such as preserving a site for future food storage and (or) providing a hospitable environment for mycorrhizae when conditions outside the root are hostile. Loss of a viable apex under conditions of drought induced the development of many lateral root primordia that did not emerge but remained dormant within the root cortex. When water was added to the growth medium, these grew out quickly and along with the new adventitious roots that sprouted from the bulbs, rejuvenated the root system. Stress periods longer than 200 d resulted in death of the majority of the roots, and the plants did not recover after watering. Key words: drought, roots, Allium cepa L., exodermis, hypodermis, dormant lateral root primordia.

Lateral root formation and nutrients: nitrogen in the spotlight

2021 ◽  
Author(s):  
Pierre-Mathieu Pélissier ◽  
Hans Motte ◽  
Tom Beeckman
Keyword(s):  
Signaling Pathways ◽  
Root System ◽  
Root Development ◽  
Lateral Root ◽  
Molecular Mechanisms ◽  
Root Formation ◽  
Lateral Roots ◽  
Nutrient Use Efficiency ◽  
Lateral Root Formation ◽  
Lateral Root Development

Abstract Lateral roots are important to forage for nutrients due to their ability to increase the uptake area of a root system. Hence, it comes as no surprise that lateral root formation is affected by nutrients or nutrient starvation, and as such contributes to the root system plasticity. Understanding the molecular mechanisms regulating root adaptation dynamics towards nutrient availability is useful to optimize plant nutrient use efficiency. There is at present a profound, though still evolving, knowledge on lateral root pathways. Here, we aimed to review the intersection with nutrient signaling pathways to give an update on the regulation of lateral root development by nutrients, with a particular focus on nitrogen. Remarkably, it is for most nutrients not clear how lateral root formation is controlled. Only for nitrogen, one of the most dominant nutrients in the control of lateral root formation, the crosstalk with multiple key signals determining lateral root development is clearly shown. In this update, we first present a general overview of the current knowledge of how nutrients affect lateral root formation, followed by a deeper discussion on how nitrogen signaling pathways act on different lateral root-mediating mechanisms for which multiple recent studies yield insights.

scholarly journals The Rhizobium leguminosarum biovar trifolii ANU794 Induces Novel Developmental Responses on the Subterranean Clover Cultivar Woogenellup

2006 ◽  
Vol 19 (5) ◽  
pp. 471-479 ◽  
Author(s):  
Angela Carmen Morris ◽  
Michael Anthony Djordjevic
Keyword(s):  
Lateral Root ◽  
Rhizobium Leguminosarum ◽  
Root Formation ◽  
Fluorescent Protein ◽  
Lateral Roots ◽  
Hybrid Structures ◽  
Nodule Development ◽  
Lateral Root Formation ◽  
Low Efficiency ◽  
Developmental Responses

The clover-nodulating Rhizobium leguminosarum bv. trifolii ANU794 initiates normal root-nodule development with abnormally low efficiency on the Trifolium subterraneum cv. Woogenellup. The cellular and developmental responses of Woogenellup roots to the site- and dose-defined inoculation of green fluorescent protein (gfp)-labeled cells of ANU843 (nodulation proficient) and ANU794 was investigated using light, fluorescence, and confocal microscopy. Strain ANU794-gfp induced three primordia types and four developmental responses at the inoculation site: true or aberrant nodules (on 5 and 25% of plants, respectively), hybrid structures (20% of plants), or lateral roots (50% of plants). The novel hybrid structures possessed nodule and lateral root-like features and unusual vascular patterning. Strain ANU794-gfp induces lateral root formation by stimulating pericycle cell divisions at all nearby protoxylem poles. Only true nodules induced by ANU794-gfp contained intracellular bacteria. In contrast, strain ANU843-gfp induced nodules only and lateral root formation was suppressed at spot inoculation sites. Primordium types were distinguishable by the emission spectrum characteristics of phenolic UV-absorbing and fluorescent compounds that accumulate in primordium cells. Hybrid primordia contained (at least) two fluorescent cell populations, suggesting that they are chimeric. The results suggest that ANU794 may produce both nodule- and lateral root-generating signals simultaneously.

Application of Phytohormones to Pea Roots After Removal of the Apex: Effect on Lateral Root Production

1979 ◽  
Vol 6 (2) ◽  
pp. 195 ◽  
Author(s):  
PB Goodwin ◽  
SC Morris
Keyword(s):  
Lateral Root ◽  
Lateral Roots ◽  
Primary Root ◽  
Root Production ◽  
Root Tip ◽  
Naphthaleneacetic Acid ◽  
Root Initiation ◽  
Lateral Root Initiation ◽  
Lateral Bud ◽  
Bud Growth

Removal of 2 mm of the primary root tip of Pisum sativum caused a complete halt to primary root elongation, but did not alter the total number of laterals formed. The auxins indole-3-acetic acid and 1-naphthaleneacetic acid, when applied to the stump in a lanolin emulsion, increased the number of lateral roots. High levels of abscisic acid and low levels of the cytokinins N6-benzylaminopurine and N6-(γ, γ-dimethylallylamino)purine, and of the gibberellins GA3 and GA7, resulted in decreased lateral root production. Kinetin was without effect. There appears to be an inverse relationship between auxins and cytokinins in root/shoot growth coordination. Auxins, which are produced in the shoot tip, inhibit lateral bud growth but promote lateral root initiation. Cytokinins, which are produced in the root tip, inhibit lateral root initiation, but promote lateral stem growth.

Plant steroid hormones

1983 ◽  
Vol 11 (5) ◽  
pp. 543-548 ◽  
Author(s):  
JAN M. C. GEUNS
Keyword(s):  
Steroid Hormones ◽  
Adventitious Root ◽  
Lateral Root ◽  
Rna Synthesis ◽  
Root Formation ◽  
Test System ◽  
Adventitious Root Formation ◽  
Receptor Protein ◽  
Lateral Root Formation ◽  
Structural Requirements

After a brief survey of the literature on the recently discovered brassinolide, some of our results with corticosteroids are given. A number of structural requirements of corticosteroids were deduced in a bioassay involving elongation growth and lateral root formation. To explain the activity of glucocorticoids, the involvement of a receptor protein is suggested as well as an enhanced RNA synthesis. However, the structural requirements found are not applicable to experiments on adventitious root formation, implying a different mode of action of corticosteroids in this test system.

Differences among Populas species in ability to form adventitious shoots and roots

1976 ◽  
Vol 6 (3) ◽  
pp. 253-261 ◽  
Author(s):  
George A. Schier ◽  
Robert B. Campbell
Keyword(s):  
Lateral Root ◽  
Root Formation ◽  
Lateral Roots ◽  
Adventitious Shoots ◽  
Root Segment ◽  
Lateral Root Formation ◽  
Root Segments ◽  
Rooting Capacity

Differences in suckering from root segments and in rooting from sucker cuttings were studied among four species of Populus, including three poplars, P. angustifolia James, P. deltoides Bartr., and P. balsamifera L., and an aspen, P. tremuloides Michx. Places where suckers originated on root segments were more variable in the poplars than in the aspen. Whereas suckers developed in the aspen only from the periderm, suckers developed in the poplars from the periderm and from cambium exposed at the cut ends of segments and lateral roots. Poplar suckers arising from the periderm originated from preexisting suppressed buds embedded in the periderm. Suckers developed in the aspen from preexisting primordia. Lateral root formation from preexisting and newly initiated meristems on root segments was common in the poplars but rare in the aspen. The presence of lateral roots increased sucker growth, and the development of suckers and lateral roots responded to the inherent polarity of the root segment. Sucker cuttings from the poplars were generally superior in rooting capacity to those from the aspen.

Analysis of lateral root growth in Arabidopsis in response to physiologically active auxin analogues

2010 ◽  
Vol 58 (1) ◽  
pp. 1-10 ◽  
Author(s):  
L. Novickienė ◽  
V. Gavelienė ◽  
L. Miliuvienė ◽  
D. Kazlauskienė ◽  
L. Pakalniškytė
Keyword(s):  
Lateral Root ◽  
Apical Meristem ◽  
Lateral Roots ◽  
Root System Architecture ◽  
Test Plant ◽  
Wild Type ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Primary Roots ◽  
The Impact

The aim of this work was to investigate the formation and development of lateral roots in model trials on Arabidopsis thaliana L. Heynh wild type (Col-0), the alf4-1 mutant and its allele by applying the physiologically active auxin analogues IBA, IAA, TA-12 and TA-14.Differences were observed between the alf4-1 mutant and its allele phenotype in the formation of lateral roots. The application of auxin analogues was unable to restore the formation of lateral roots in the alf4-1 mutant. In some cases, under the impact of IBA (1 μM), a cluster of xylem cells was activated in the pericycle of the primary roots and lateral root primordia were formed. The auxin analogues induced the growth of primary roots in the alf4-1 allele and the formation and growth of lateral roots. The impact of IBA (1 μM), TA-12 (1 mM) and IAA (1 μM) was particularly evident. The intense formation of lateral roots under the impact of IBA and TA-12 could be related with the ability of these compounds to intensify mitotic activity in the apical meristem cells of the lateral roots. New data were obtained, showing that IBA and other physiologically active auxin analogues can modify the root system architecture of the test-plant Arabidopsis .

scholarly journals Flavonols modulate lateral root emergence by scavenging reactive oxygen species in Arabidopsis thaliana

2020 ◽  
pp. jbc.RA120.014543
Author(s):  
Jordan M. Chapman ◽  
Gloria K. Muday
Keyword(s):  
Arabidopsis Thaliana ◽  
Root Development ◽  
Lateral Root ◽  
Lateral Roots ◽  
Negative Regulator ◽  
Wild Type ◽  
Root Primordia ◽  
Lateral Root Primordia ◽  
Lateral Root Development ◽  
Genes Encoding

Flavonoids are a class of specialized metabolites with subclasses including flavonols and anthocyanins, which have unique properties as antioxidants. Flavonoids modulate plant development, but whether and how they impact lateral root development is unclear. We examined potential roles for flavonols in this process using Arabidopsis thaliana mutants with defects in genes encoding key enzymes in flavonoid biosynthesis. We observed the tt4 and fls1 mutants, which produce no flavonols, have increased lateral root emergence. The tt4 root phenotype was reversed by genetic and chemical complementation. To more specifically define the flavonoids involved, we tested an array of flavonoid biosynthetic mutants, eliminating roles for anthocyanins and the flavonols quercetin and isorhamnetin in modulating root development. Instead, two tt7 mutant alleles, with defects in a branchpoint enzyme blocking quercetin biosynthesis, formed reduced numbers of lateral roots, and tt7-2 had elevated levels of kaempferol. Using a flavonol-specific dye, we observed that in the tt7-2 mutant, kaempferol accumulated within lateral root primordia at higher levels than wild-type. These data are consistent with kaempferol, or downstream derivatives, acting as a negative regulator of lateral root emergence. We examined ROS accumulation using ROS-responsive probes and found reduced fluorescence of a superoxide-selective probe within the primordia of tt7-2 compared to wild type, but not in the tt4 mutant, consistent with opposite effects of these mutants on lateral root emergence. These results support a model in which increased level of kaempferol in the lateral root primordia of tt7-2 reduces superoxide concentration and ROS-stimulated lateral root emergence.

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