Limits...
WRKY6 restricts Piriformospora indica-stimulated and phosphate-induced root development in Arabidopsis.

Bakshi M, Vahabi K, Bhattacharya S, Sherameti I, Varma A, Yeh KW, Baldwin I, Johri AK, Oelmüller R - BMC Plant Biol. (2015)

Bottom Line: The results demonstrate that P. indica promotes phosphate uptake and root development under Pi limitation in wrky6 mutant.This is associated with the stimulation of PHOSPHATE1 expression and ethylene production.They can be tested for optimizing root growth in model and agricultural plants.

View Article: PubMed Central - PubMed

Affiliation: Institute of General Botany and Plant Physiology, Friedrich-Schiller-University Jena, Dornburgerstr. 159, D-07743, Jena, Germany. bakshi.madhunita@gmail.com.

ABSTRACT

Background: Arabidopsis root growth is stimulated by Piriformospora indica, phosphate limitation and inactivation of the WRKY6 transcription factor. Combinations of these factors induce unexpected alterations in root and shoot growth, root architecture and root gene expression profiles.

Results: The results demonstrate that P. indica promotes phosphate uptake and root development under Pi limitation in wrky6 mutant. This is associated with the stimulation of PHOSPHATE1 expression and ethylene production. Expression profiles from the roots of wrky6 seedlings identified genes involved in hormone metabolism, transport, meristem, cell and plastid proliferation, and growth regulation. 25 miRNAs were also up-regulated in these roots. We generated and discuss here a list of common genes which are regulated in growing roots and which are common to all three growth stimuli investigated in this study.

Conclusion: Since root development of wrky6 plants exposed to P. indica under phosphate limitation is strongly promoted, we propose that common genes which respond to all three growth stimuli are central for the control of root growth and architecture. They can be tested for optimizing root growth in model and agricultural plants.

Show MeSH

Related in: MedlinePlus

Phenotypes of WT and wrky6 seedlings grown on 2.5 mM and 0.25 mM Pi in the medium. 10 day-old seedlings grown on MS medium were transferred to PNM media containing the two different Pi concentrations for additional 3, 6 and 12 days, either in the presence of P. indica (right panels) or plaques without the fungus (left panels). All seedlings were grown at 22 °C and 70–80 % humidity in a 16-h light/8-h dark cycle. Photos show typical view of more than 10 repetitions. Bar: 1 cm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC4697310&req=5

Fig1: Phenotypes of WT and wrky6 seedlings grown on 2.5 mM and 0.25 mM Pi in the medium. 10 day-old seedlings grown on MS medium were transferred to PNM media containing the two different Pi concentrations for additional 3, 6 and 12 days, either in the presence of P. indica (right panels) or plaques without the fungus (left panels). All seedlings were grown at 22 °C and 70–80 % humidity in a 16-h light/8-h dark cycle. Photos show typical view of more than 10 repetitions. Bar: 1 cm

Mentions: WT and wrky6 seedlings (Fig. 1) were grown with/without P. indica on vertical PNM plates containing 2.5 or 0.25 mM Pi for 3, 6 and 12 days. A growth-promoting effect of the fungus on the seedling’s development became visible 3 days post incubation (dpi) and increased with decreasing Pi concentrations in the medium. In particular, root growth of both WT and wrky6 seedlings was promoted with decreasing Pi concentrations and further stimulated by the fungus (Figs. 1 and 2). Closer inspection revealed that the roots are denser and bushier in the presence of P. indica because the number and lengths of both lateral roots (Figs. 1 and 2a) as well as root hairs (Fig. 2b–d) were increased. Furthermore, stimulation of root growth by P. indica in the WT under Pi limitation was restricted by WRKY6. This is particularly striking for seedlings grown on 0.25 mM Pi (Figs. 1 and 2): the growth-stimulating effect of P. indica is much stronger for wrky6 roots than WT roots (Fig. 2b–d). Finally, consistent with the literature on root development after AM colonization [2], the primary root lengths of WT and wrky6 seedlings were shorter under Pi limitation conditions (Fig. 2e). These results suggest that WRKY6 has a strong influence on the root architecture and that wrky6 plants perform better than WT plants both in response to P. indica and Pi limitation.Fig. 1


WRKY6 restricts Piriformospora indica-stimulated and phosphate-induced root development in Arabidopsis.

Bakshi M, Vahabi K, Bhattacharya S, Sherameti I, Varma A, Yeh KW, Baldwin I, Johri AK, Oelmüller R - BMC Plant Biol. (2015)

Phenotypes of WT and wrky6 seedlings grown on 2.5 mM and 0.25 mM Pi in the medium. 10 day-old seedlings grown on MS medium were transferred to PNM media containing the two different Pi concentrations for additional 3, 6 and 12 days, either in the presence of P. indica (right panels) or plaques without the fungus (left panels). All seedlings were grown at 22 °C and 70–80 % humidity in a 16-h light/8-h dark cycle. Photos show typical view of more than 10 repetitions. Bar: 1 cm
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4697310&req=5

Fig1: Phenotypes of WT and wrky6 seedlings grown on 2.5 mM and 0.25 mM Pi in the medium. 10 day-old seedlings grown on MS medium were transferred to PNM media containing the two different Pi concentrations for additional 3, 6 and 12 days, either in the presence of P. indica (right panels) or plaques without the fungus (left panels). All seedlings were grown at 22 °C and 70–80 % humidity in a 16-h light/8-h dark cycle. Photos show typical view of more than 10 repetitions. Bar: 1 cm
Mentions: WT and wrky6 seedlings (Fig. 1) were grown with/without P. indica on vertical PNM plates containing 2.5 or 0.25 mM Pi for 3, 6 and 12 days. A growth-promoting effect of the fungus on the seedling’s development became visible 3 days post incubation (dpi) and increased with decreasing Pi concentrations in the medium. In particular, root growth of both WT and wrky6 seedlings was promoted with decreasing Pi concentrations and further stimulated by the fungus (Figs. 1 and 2). Closer inspection revealed that the roots are denser and bushier in the presence of P. indica because the number and lengths of both lateral roots (Figs. 1 and 2a) as well as root hairs (Fig. 2b–d) were increased. Furthermore, stimulation of root growth by P. indica in the WT under Pi limitation was restricted by WRKY6. This is particularly striking for seedlings grown on 0.25 mM Pi (Figs. 1 and 2): the growth-stimulating effect of P. indica is much stronger for wrky6 roots than WT roots (Fig. 2b–d). Finally, consistent with the literature on root development after AM colonization [2], the primary root lengths of WT and wrky6 seedlings were shorter under Pi limitation conditions (Fig. 2e). These results suggest that WRKY6 has a strong influence on the root architecture and that wrky6 plants perform better than WT plants both in response to P. indica and Pi limitation.Fig. 1

Bottom Line: The results demonstrate that P. indica promotes phosphate uptake and root development under Pi limitation in wrky6 mutant.This is associated with the stimulation of PHOSPHATE1 expression and ethylene production.They can be tested for optimizing root growth in model and agricultural plants.

View Article: PubMed Central - PubMed

Affiliation: Institute of General Botany and Plant Physiology, Friedrich-Schiller-University Jena, Dornburgerstr. 159, D-07743, Jena, Germany. bakshi.madhunita@gmail.com.

ABSTRACT

Background: Arabidopsis root growth is stimulated by Piriformospora indica, phosphate limitation and inactivation of the WRKY6 transcription factor. Combinations of these factors induce unexpected alterations in root and shoot growth, root architecture and root gene expression profiles.

Results: The results demonstrate that P. indica promotes phosphate uptake and root development under Pi limitation in wrky6 mutant. This is associated with the stimulation of PHOSPHATE1 expression and ethylene production. Expression profiles from the roots of wrky6 seedlings identified genes involved in hormone metabolism, transport, meristem, cell and plastid proliferation, and growth regulation. 25 miRNAs were also up-regulated in these roots. We generated and discuss here a list of common genes which are regulated in growing roots and which are common to all three growth stimuli investigated in this study.

Conclusion: Since root development of wrky6 plants exposed to P. indica under phosphate limitation is strongly promoted, we propose that common genes which respond to all three growth stimuli are central for the control of root growth and architecture. They can be tested for optimizing root growth in model and agricultural plants.

Show MeSH
Related in: MedlinePlus