scholarly journals Hormonal response and root architecture in Arabidopsis thaliana subjected to heavy metals

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Antonella Vitti ◽  
Maria Nuzzaci ◽  
Antonio Scopa ◽  
Giuseppe Tataranni ◽  
Imma Tamburrino ◽  
...  
Keyword(s):  
Root Architecture ◽  
Lateral Roots ◽  
Root Hairs ◽  
Polymerase Chain Reaction Analysis ◽  
Zeatin Riboside ◽  
Morphological Alterations ◽  
Cytokinin Synthesis ◽  
Polymerase Chain ◽  
Abscisic Acid Level ◽  
Indole 3 Acetic Acid

In this work, specific concentrations of cadmium, copper and zinc in double combination, were supplied for 12 days to growing seedlings of the model species <em>Arabidopsis</em> <em>thaliana</em>. Metal accumulation was measured in roots and shoots. Microscopic analyses revealed that root morphology was affected by metals, and that the root and shoot levels of indole-3-acetic acid, <em>trans</em>-zeatin riboside and dihydrozeatin riboside varied accordingly. Minor modifications in gibberellic acid levels occurred in the Zinc treatments, whereas abscisic acid level did not change after the exposition to metals. Reverse transcription polymerase chain reaction analysis of some genes involved in auxin and cytokinin synthesis (<em>AtAAO</em>, <em>AtNIT</em> and <em>AtIPT</em>) revealed that their expression were not affected by metal treatments. The root morphological alterations that resulted in an increased surface area, due to the formation of root hairs and lateral roots, could be signs of the response to metal stress in terms of a functionally-addressed reorientation of root growth. The root system plasticity observed could be important for better understanding the manner in which the root architecture is shaped by environmental and hormonal stimuli.

Effect of Exogenous Abscisic acid (ABA) on the Morphology, Phytohormones, and Related Gene Expression of Developing Lateral Roots in ‘Qingzhen 1’

2021 ◽  
Author(s):  
Xiaoyun Zhang ◽  
Shaohuan Li ◽  
Ting Tang ◽  
Jiangping Mao ◽  
Ke Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Abscisic Acid ◽  
Early Stage ◽  
Lateral Roots ◽  
Plant Stress ◽  
Zeatin Riboside ◽  
Regulation Mechanism ◽  
Expression Levels ◽  
Primary Stress ◽  
Indole 3 Acetic Acid

Abstract Lateral roots (LRs) are critical for plant stress tolerance and productivity. Understanding how hormones and genes interact in a fluctuating environment to coordinate LR development is a major challenge. Abscisic acid (ABA) is the primary stress-responsive hormone and mediates LR development in various plant species. However, the effect of exogenous ABA on LR development has not been elucidated in apple. In this study, ‘Qingzhen 1’ was treated with exogenous 5 µM ABA for 20 days to investigate the regulation mechanism of ABA on LR development. Morphological observations advocated that ABA inhibited both LR and shoot development in ‘Qingzhen 1’ apple plants, where the root number was 16.94%, the root length was 30.32%, the plant height was 10.88%, and the stem thickness was 8.08% lower than those in the control plants. Meanwhile, the endogenous ABA concentration was significantly increased, but the indole-3-acetic acid (IAA), zeatin riboside (ZR), and jasmonic acid (JA) concentrations were significantly decreased with ABA treatment. Furthermore, the expression levels of ABA-related genes (MdCYP707A2, MdABI1, MdAREB2, and MdABF3) were significantly upregulated, while the expression levels of auxin-related genes (MdYUCCA3, MdYUCCA8, MdPIN1 MdPIN2, MdPIN3, and MdARF19), root development-related genes (MdWOX5 and MdWOX11), and cell cycle-related genes (MdCYCD1;1 and MdCYCD3;1) were significantly downregulated at the early stage of ABA treatment, which act together on the inhibition of LR development. Taken together, the changes in hormone levels and gene expression resulted in inhibited LR development of apple plants in response to ABA.

Demonstration of the indolepyruvate decarboxylase gene homologue in different auxin-producing species of the Enterobacteriaceae

1994 ◽  
Vol 40 (12) ◽  
pp. 1072-1076 ◽  
Author(s):  
Wolfgang Zimmer ◽  
Barbara Hundeshagen ◽  
Edith Niederau
Keyword(s):  
Polymerase Chain Reaction ◽  
Klebsiella Oxytoca ◽  
Pyruvate Decarboxylase ◽  
Enterobacter Agglomerans ◽  
Chain Reaction ◽  
Acetic Acid Production ◽  
Conserved Regions ◽  
Polymerase Chain ◽  
Gene Homologue ◽  
Indole 3 Acetic Acid

Different Enterobacteriaceae were assayed for their ability to produce the plant hormone indole-3-acetate with the aim to study the distribution of the indole-3-pyruvate pathway, which is known to be involved in the production of indole-3-acetate in a root-associated Enterobacter cloacae strain. Other E. cloacae strains, and also Enterobacter agglomerans strains, Pantoea agglomerans, Klebsiella aerogenes, and Klebsiella oxytoca were found to convert tryptophan into indole-3-acetate. As it was also intended to identify the conserved regions of the indole-3-pyruvate decarboxylase, which is involved in producing indole-3-acetate in the E. cloacae strain, oligonucleotide primers were synthesized for different regions of the corresponding gene. One pair of these primers allowed us to amplify a segment of the predicted size by the polymerase chain reaction with DNA of the seven different Enterobacteriaceae that produce indole-3-acetate. Segments of five strains were cloned and sequenced. All sequences showed significant homology to the indole-3-pyruvate decarboxylase gene. As in addition a positive DNA–DNA hybridization signal was detected in the seven strains using the E. cloacae or E. agglomerans segments as a probe, indole-3-acetate biosynthesis is suggested to be catalyzed via the indole-3-pyruvate pathway not only in E. cloacae but also in the other soil-living Enterobacteriaceae. Conserved regions were detected in the indole-3-decarboxylase by alignment of the now-available five different partial sequences. These regions should enable identification of the gene in other bacterial families or even in plants.Key words: indole-3-pyruvate decarboxylase, indole-3-acetic acid production, auxin, polymerase chain reaction, Enterobacteriaceae.

scholarly journals Effects of light and ethylene on endogenous hormones and development of Catasetum fimbriatum (Orchidaceae)

2006 ◽  
Vol 18 (3) ◽  
pp. 359-365 ◽  
Author(s):  
Rogério M. Suzuki ◽  
Gilberto B. Kerbauy
Keyword(s):  
Leaf Growth ◽  
Shoot Elongation ◽  
Zeatin Riboside ◽  
Endogenous Hormones ◽  
Light Conditions ◽  
Active Growth ◽  
Dark Light ◽  
The Difference ◽  
Catasetum Fimbriatum ◽  
Indole 3 Acetic Acid

This study attempted to clarify the effects of dark, light and ethylene on plant growth and endogenous levels of indole-3-acetic acid (IAA), cytokinins and abscisic acid in Catasetum fimbriatum. Dark-incubation fully inhibited root and pseudobulb formation as well as leaf growth, but favored shoot elongation. The results of continuous and active growth in dark-incubated shoots (stolons) were induced by strong apical meristem sink activity and by the significantly increased levels of cytokinins in shoots. In fact, shoot length, cytokinin and IAA levels in dark-incubated shoots were about twice as great as for those grown under light conditions. Moreover, the total cytokinin level in shoots of C. fimbriatum under light conditions without ethylene was significantly higher than that found in roots. High levels of cytokinins in dark-grown stolons may be closely related to the absence of roots in C. fimbriatum. Under light conditions, the increased IAA level in shoots is mediated by ethylene. However, ethylene caused a significant increase of cytokinins in roots of light-treated plants, which may be involved in the retardation of root growth. Since the difference of cytokinins in shoots between ethylene-treated and non-treated plants under light conditions is small, it is concluded that the marked inhibition of leaf growth in ethylene-treated plants can be attributed to ethylene. Zeatin and zeatin riboside are the major cytokinins in C. fimbriatum regardless of the light conditions, ethylene treatment or organ types.

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