Commentary: Plant Auxin Biosynthesis Did Not Originate in Charophytes.
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ABSTRACT:
SUBMITTER: Wang C
PROVIDER: S-EPMC4754409 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Plant architecture is one of the key factors that affect plant survival and productivity. Plant body structure is established through the iterative initiation and outgrowth of lateral organs, which are derived from the shoot apical meristem and root apical meristem, after embryogenesis. Here we report that ADP1, a putative MATE (multidrug and toxic compound extrusion) transporter, plays an essential role in regulating lateral organ outgrowth, and thus in maintaining normal architecture of Arabidopsis. Elevated expression levels of ADP1 resulted in accelerated plant growth rate, and increased the numbers of axillary branches and flowers. Our molecular and genetic evidence demonstrated that the phenotypes of plants over-expressing ADP1 were caused by reduction of local auxin levels in the meristematic regions. We further discovered that this reduction was probably due to decreased levels of auxin biosynthesis in the local meristematic regions based on the measured reduction in IAA levels and the gene expression data. Simultaneous inactivation of ADP1 and its three closest homologs led to growth retardation, relative reduction of lateral organ number and slightly elevated auxin level. Our results indicated that ADP1-mediated regulation of the local auxin level in meristematic regions is an essential determinant for plant architecture maintenance by restraining the outgrowth of lateral organs.
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Project description:Amidases [EC 3.5.1.4] capable of converting indole-3-acetamide (IAM) into the major plant growth hormone indole-3-acetic acid (IAA) are assumed to be involved in auxin de novo biosynthesis. With the emerging amount of genomics data, it was possible to identify over forty proteins with substantial homology to the already characterized amidases from Arabidopsis and tobacco. The observed high conservation of amidase-like proteins throughout the plant kingdom may suggest an important role of theses enzymes in plant development. Here, we report cloning and functional analysis of four, thus far, uncharacterized plant amidases from Oryza sativa, Sorghum bicolor, Medicago truncatula, and Populus trichocarpa. Intriguingly, we were able to demonstrate that the examined amidases are also capable of converting phenyl-2-acetamide (PAM) into phenyl-2-acetic acid (PAA), an auxin endogenous to several plant species including Arabidopsis. Furthermore, we compared the subcellular localization of the enzymes to that of Arabidopsis AMI1, providing further evidence for similar enzymatic functions. Our results point to the presence of a presumably conserved pathway of auxin biosynthesis via IAM, as amidases, both of monocot, and dicot origins, were analyzed.
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Project description:Plant height is one of the key agronomic traits affecting soybean yield. The cytokinin response factors (CRFs), as a branch of the APETALA2/ethylene responsive factor (AP2/ERF) super gene family, have been reported to play important roles in regulating plant growth and development. However, their functions in soybean remain unknown. This study characterized a soybean CRF gene named GmCRF4a by comparing the performance of the homozygous Gmcrf4a-1 mutant, GmCRF4a overexpression (OX) and co-silencing (CS) lines. Phenotypic analysis showed that overexpression of GmCRF4a resulted in taller hypocotyls and epicotyls, more main stem nodes, and higher plant height. While down-regulation of GmCRF4a conferred shorter hypocotyls and epicotyls, as well as a reduction in plant height. The histological analysis results demonstrated that GmCRF4a promotes epicotyl elongation primarily by increasing cell length. Furthermore, GmCRF4a is required for the expression of GmYUCs genes to elevate endogenous auxin levels, which may subsequently enhance stem elongation. Taken together, these observations describe a novel regulatory mechanism in soybean, and provide the basis for elucidating the function of GmCRF4a in auxin biosynthesis pathway and plant heigh regulation in plants.
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Project description:The phytohormone auxin plays critical roles in the regulation of plant growth and development. Indole-3-acetic acid (IAA) has been recognized as the major auxin for more than 70 y. Although several pathways have been proposed, how auxin is synthesized in plants is still unclear. Previous genetic and enzymatic studies demonstrated that both TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS (TAA) and YUCCA (YUC) flavin monooxygenase-like proteins are required for biosynthesis of IAA during plant development, but these enzymes were placed in two independent pathways. In this article, we demonstrate that the TAA family produces indole-3-pyruvic acid (IPA) and the YUC family functions in the conversion of IPA to IAA in Arabidopsis (Arabidopsis thaliana) by a quantification method of IPA using liquid chromatography-electrospray ionization-tandem MS. We further show that YUC protein expressed in Escherichia coli directly converts IPA to IAA. Indole-3-acetaldehyde is probably not a precursor of IAA in the IPA pathway. Our results indicate that YUC proteins catalyze a rate-limiting step of the IPA pathway, which is the main IAA biosynthesis pathway in Arabidopsis.
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Project description:The plant proliferation is linked with auxins which in turn play a pivotal role in the rate of growth. Also, auxin concentrations could provide insights into the age, stress, and events leading to flowering and fruiting in the sessile plant kingdom. The role in rejuvenation and plasticity is now evidenced. Interest in plant auxins spans many decades, information from different plant families for auxin concentrations, transcriptional, and epigenetic evidences for gene regulation is evaluated here, for getting an insight into pattern of auxin biosynthesis. This biosynthesis takes place via an tryptophan-independent and tryptophan-dependent pathway. The independent pathway initiated before the tryptophan (trp) production involves indole as the primary substrate. On the other hand, the trp-dependent IAA pathway passes through the indole pyruvic acid (IPyA), indole-3-acetaldoxime (IAOx), and indole acetamide (IAM) pathways. Investigations on trp-dependent pathways involved mutants, namely yucca (1-11), taa1, nit1, cyp79b and cyp79b2, vt2 and crd, and independent mutants of tryptophan, ins are compiled here. The auxin conjugates of the IAA amide and ester-linked mutant gh3, iar, ilr, ill, iamt1, ugt, and dao are remarkable and could facilitate the assimilation of auxins. Efforts are made herein to provide an up-to-date detailed information about biosynthesis leading to plant sustenance. The vast information about auxin biosynthesis and homeostasis is consolidated in this review with a simplified model of auxin biosynthesis with keys and clues for important missing links since auxins can enable the plants to proliferate and override the environmental influence and needs to be probed for applications in sustainable agriculture.Supplementary informationThe online version contains supplementary material available at 10.1007/s13205-023-03709-6.
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Project description:Recently, 2-aminoxy-3-phenylpropionic acid (L-AOPP) had been demonstrated to possess an inhibitory activity against IAA biosynthesis but the molecular basis of the action was unclear. To investigate the function of L-AOPP in relation to Auxin biosynthesis, we conducted microarray analysis.
2015-12-31 | GSE30093 | GEO
Project description:We found that auxin stimulates gene expression of DWF4, which encodes a rate-dertermining step in brassinosteroid biosynthesis pathways. This increased gene expressioin subsequently led to elevation of the biosynthetic flux in Arabidopsis roots. To determine the list of genes that are regulated by auxin-synthesizing brassinosteroids, we challenged Arabidopsis seedlings with either auxin only or auxin plus brassinosteroid biosynthetic inhibitor brassinazole. Keywords: Hormone treatment Arabidopsis seedlings (Columbia ecotype) were grown for 10 d on 1× MS agar-solidified media under long-day conditions (16:8, white light and dark cycle). The seedlings were then transferred to 2 different liquid media containing either 10–7 M 2,4-D or 10–7 M 2,4-D plus 10–6 M brassinazole. After 8 h of treatment, the seedlings were blotted with paper towels to remove excess media and subject to total RNA isolation. Total RNAs isolated from each batch were prepared from 3 replicate seedlings using an RNeasy plant mini kit (Qiagen, Germany).
2011-02-15 | E-GEOD-12964 | biostudies-arrayexpress
Project description:Plant development is regulated by both synergistic and antagonistic interactions of different phytohormones, including a complex crosstalk between ethylene and auxin. For instance, auxin and ethylene synergistically control primary root elongation and root hair formation. However, a lack of chemical agents that specifically modulate ethylene or auxin production has precluded precise delineation of the contribution of each hormone to root development. Here, we performed a chemical genetic screen based on the recovery of root growth in ethylene-related Arabidopsis mutants with constitutive "short root" phenotypes (eto1-2 and ctr1-1). We found that ponalrestat exposure recovers root elongation in these mutants in an ethylene signal-independent manner. Genetic and pharmacological investigations revealed that ponalrestat inhibits the enzymatic activity of the flavin-containing monooxygenase YUCCA, which catalyzes the rate-limiting step of the indole-3-pyruvic acid branch of the auxin biosynthesis pathway. In summary, our findings have identified a YUCCA inhibitor that may be useful as a chemical tool to dissect the distinct steps in auxin biosynthesis and in the regulation of root development.
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Project description:We found that auxin stimulates gene expression of DWF4, which encodes a rate-dertermining step in brassinosteroid biosynthesis pathways. This increased gene expressioin subsequently led to elevation of the biosynthetic flux in Arabidopsis roots. To determine the list of genes that are regulated by auxin-synthesizing brassinosteroids, we challenged Arabidopsis seedlings with either auxin only or auxin plus brassinosteroid biosynthetic inhibitor brassinazole. Keywords: Hormone treatment
2011-02-15 | GSE12964 | GEO
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