| 1. |
- Ortiz-García, Paloma, et al.
(författare)
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The Indole-3-Acetamide-Induced Arabidopsis Transcription Factor MYB74 Decreases Plant Growth and Contributes to the Control of Osmotic Stress Responses
- 2022
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Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- The accumulation of the auxin precursor indole-3-acetamide (IAM) in the ami1 mutant has recently been reported to reduce plant growth and to trigger abiotic stress responses in Arabidopsis thaliana. The observed response includes the induction of abscisic acid (ABA) biosynthesis through the promotion of NCED3 expression. The mechanism by which plant growth is limited, however, remained largely unclear. Here, we investigated the transcriptional responses evoked by the exogenous application of IAM using comprehensive RNA-sequencing (RNA-seq) and reverse genetics approaches. The RNA-seq results highlighted the induction of a small number of genes, including the R2R3 MYB transcription factor genes MYB74 and MYB102. The two MYB factors are known to respond to various stress cues and to ABA. Consistent with a role as negative plant growth regulator, conditional MYB74 overexpressor lines showed a considerable growth reduction. RNA-seq analysis of MYB74 mutants indicated an association of MYB74 with responses to osmotic stress, water deprivation, and seed development, which further linked MYB74 with the observed ami1 osmotic stress and seed phenotype. Collectively, our findings point toward a role for MYB74 in plant growth control and in responses to abiotic stress stimuli.
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| 2. |
- Pérez-Alonso, Marta-Marina, et al.
(författare)
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Endogenous indole-3-acetamide levels contribute to the crosstalk between auxin and ABA, and trigger plant stress responses in Arabidopsis thaliana
- 2021
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Ingår i: Journal of Experimental Botany. - : Oxford University Press (OUP). - 1460-2431 .- 0022-0957. ; 72:2, s. 459-475
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Tidskriftsartikel (refereegranskat)abstract
- The evolutionary success of plants relies to a large extent on their extraordinary ability to adapt to changes in their environment. These adaptations require that plants balance their growth with their stress responses. Plant hormones are crucial mediators orchestrating the underlying adaptive processes. However, whether and how the growth-related hormone auxin and the stress-related hormones jasmonic acid (JA), salicylic acid, and abscisic acid (ABA) are coordinated remains largely elusive. Here, we analyze the physiological role of AMIDASE 1 (AMI1) in plant growth and its possible connection to plant adaptations to abiotic stresses. AMI1 contributes to cellular auxin homeostasis by catalyzing the conversion of indole-acetamide into the major plant auxin indole-3-acetic acid. Functional impairment of AMI1 increases the plants' stress status rendering mutant plants more susceptible to abiotic stresses. Transcriptomic analysis of ami1 mutants disclosed the reprogramming of a considerable number of stress-related genes, including JA and ABA biosynthesis genes. The ami1 mutants exhibit only moderately repressed growth, but an enhanced ABA accumulation, which suggests a role for AMI1 in the crosstalk between auxin and ABA. Altogether, our results suggest that AMI1 is involved in coordinating the trade-off between plant growth and stress responses, balancing auxin with ABA homeostasis.
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| 3. |
- Pérez-Alonso, Marta-Marina, et al.
(författare)
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The calcium sensor CBL7 is required for Serendipita indica-induced growth stimulation in Arabidopsis thaliana, controlling defense against the endophyte and K+ homoeostasis in the symbiosis
- 2022
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Ingår i: Plant, Cell and Environment. - : John Wiley & Sons. - 0140-7791 .- 1365-3040. ; 45:11, s. 3367-3382
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Tidskriftsartikel (refereegranskat)abstract
- Calcium is an important second messenger in plants. The activation of Ca2+ signalling cascades is critical in the activation of adaptive processes in response to environmental stimuli. Root colonization by the growth promoting endophyte Serendipita indica involves the increase of cytosolic Ca2+ levels in Arabidopsis thaliana. Here, we investigated transcriptional changes in Arabidopsis roots during symbiosis with S. indica. RNA-seq profiling disclosed the induction of Calcineurin B-like 7 (CBL7) during early and later phases of the interaction. Consistently, reverse genetic evidence highlighted the functional relevance of CBL7 and tested the involvement of a CBL7-CBL-interacting protein kinase 13 signalling pathway. The loss-of-function of CBL7 abolished the growth promoting effect and affected root colonization. The transcriptomics analysis of cbl7 revealed the involvement of this Ca2+ sensor in activating plant defense responses. Furthermore, we report on the contribution of CBL7 to potassium transport in Arabidopsis. We analysed K+ contents in wild-type and cbl7 plants and observed a significant increase of K+ in roots of cbl7 plants, while shoot tissues demonstrated K+ depletion. Taken together, our work associates CBL7 with an important role in the mutual interaction between Arabidopsis and S. indica and links CBL7 to K+ transport.
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| 4. |
- Sánchez‐Parra, Beatriz, et al.
(författare)
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Accumulation of the auxin precursor indole‐3‐acetamide curtails growth through the repression of ribosome‐biogenesis and development‐related transcriptional networks
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 22:4
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Tidskriftsartikel (refereegranskat)abstract
- The major auxin, indole‐3‐acetic acid (IAA), is associated with a plethora of growth and developmental processes including embryo development, expansion growth, cambial activity, and the induction of lateral root growth. Accumulation of the auxin precursor indole‐3‐acetamide (IAM) induces stress related processes by stimulating abscisic acid (ABA) biosynthesis. How IAM signaling is controlled is, at present, unclear. Here, we characterize the ami1 rooty double mutant, that we initially generated to study the metabolic and phenotypic consequences of a simultaneous genetic blockade of the indole glucosinolate and IAM pathways in Arabidopsis thaliana. Our mass spectro-metric analyses of the mutant revealed that the combination of the two mutations is not sufficient to fully prevent the conversion of IAM to IAA. The detected strong accumulation of IAM was, how-ever, recognized to substantially impair seed development. We further show by genome‐wide expression studies that the double mutant is broadly affected in its translational capacity, and that a small number of plant growth regulating transcriptional circuits are repressed by the high IAM content in the seed. In accordance with the previously described growth reduction in response to elevated IAM levels, our data support the hypothesis that IAM is a growth repressing counterpart to IAA.
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