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Morphological and gene expression pattern changes in wrky46 mutant Arabidopsis thaliana under altered gravity conditions
- Source :
- Botany. June, 2015, Vol. 93 Issue 6, p333, 11 p.
- Publication Year :
- 2015
-
Abstract
- Arabidopsis roots are important organs for gravity sensing and gravitropic response. Long-term exposure of Arabidopsis to three-dimensional (3D) clinorotation was found to result in increased expression of WRKY46. In this study, the response of wrky46 mutants, constructed by T-DNA insertion, to simulated microgravity and gravistimulation by reorientation was studied. Microgravity conditions were simulated using a 3D clinostat, which simulates weightlessness. Morphological changes, such as root coiling, waving, and multidirectional growth patterns, were observed in the wild type (WT) seedlings after only 4 days of 3D clinorotation treatment, while in the wrky46 mutant seedlings, the changes observed were minimal compared with those of WT seedlings. Polar auxin transport played an important role in the observed morphological changes. Therefore, expression of the polar auxin transport genes AUX1, PIN2, -3, -4, and -7, and ARG1 was analyzed. Their expression was found to be higher in wrky46 seedlings than in WT seedlings under 3D clinorotation. Gravistimulation by reorientation was achieved by horizontally reorienting the seedlings. Root tip bending to 90[degrees] was observed in all WT seedlings within 18-20 h, whereas in mutant seedlings, bending of the root tip to a right angle took more than 20 h. AXR expression is known to directly correlate with root tip bending. The expression of AXR1, -2, -3, -4 was found to be higher in WT seedlings relative to mutant seedlings under gravistimulation by reorientation. However, their expression was relatively low in both WT and wrky46 plants under 3D clinorotation. These results suggest that WRKY46 plays an important role in the root gravitropic response, and in the reduction of polar auxin transport that is necessary for decreasing the effect of gravity due to clinorotation. Key words: Arabidopsis, 3D clinorotation, gravistimulation by reorientation, WRKY, wrky46 mutant. Les racines d'Arabidopsis sont des organes importants pour la detection de la gravite et la reponse geotropique. Une exposition a long terme d'Arabidopsis a une clinorotation en 3D s'est averee resulter en une augmentation de l'expression de WKRY46. Dans cette etude, la reponse de mutants wkry46, construits au moyen d'une insertion par un ADN-T, a une microgravite simulee et a une gravistimulation par reorientation a ete etudiee. Les conditions de microgravite ont ete simulees a l'aide d'un clinostat qui simule l'apesanteur. Des changements morphologiques comme l'enracinement en vrille, l'ondulation et les patrons de croissance multidirectionnelle ont ete observes chez les pousses sauvages apres seulement 4 jours de traitement en clinorotation en 3D, alors que chez les pousses des mutants wrky46, les changements observes etaient minimes comparativement aux pousses sauvages. Le transport polaire de l'auxine jouait un role important dans les changements morphologiques observes. Ainsi, l'expression des genes de transport de l'auxine AUX1, PIN2, -3, -4 et -7, et ARG1 a ete analysee. Leur expression s'est revelee plus elevee chez les pousses wrky46 que chez les pousses sauvages soumises a la clinorotation en 3D. La gravistimulation par reorientation a ete obtenue en reorientant les pousses de maniere horizontale. Une flexion de l'apex des racines a 90[degrees] etait observee chez toutes les pousses sauvages en moins de 18-20 h, alors que chez les pousses des mutants, la flexion de l'apex des racines a angle droit necessitait plus de 20 h. L'expression de AXR est connue pour etre en correlation directe avec la flexion de l'apex des racines. L'expression de AXR1, -2, -3 et -4 etait plus elevee chez les pousses sauvages relativement aux pousses mutantes placees en condition de gravistimulation par reorientation. Cependant, leur expression etait relativement faible tant chez les plants sauvages que les plants mutants en condition de clinorotation en 3D. Ces resultats suggerent que WRKY46 joue un role important dans la reponse geotropique des racines et dans la reduction du transport polaire de l'auxine, necessaire a la diminution de l'effet de la gravite causee par la clinorotation. [Traduit par la Redaction] Mots-cles : Arabidopsis, clinorotation en 3D, gravistimulation par reorientation, WRKY, mutant wrky46.<br />Introduction Plants adapt their growth in response to environmental stress. A change in gravity is a stressful condition for plants, and they respond to it via changes not only at [...]
Details
- Language :
- English
- ISSN :
- 19162790
- Volume :
- 93
- Issue :
- 6
- Database :
- Gale General OneFile
- Journal :
- Botany
- Publication Type :
- Academic Journal
- Accession number :
- edsgcl.419269621
- Full Text :
- https://doi.org/10.1139/cjb-2014-0252