Interaction of gravitropism and phototropism in roots of Brassica oleracea

Luigi Gennaro Izzo*, Leone Ermes Romano, Lucius Wilhelminus Franciscus Muthert, Maurizio Iovane, Fiore Capozzi, Aránzazu Manzano, Malgorzata Ciska, Raúl Herranz, F. Javier Medina, John Z. Kiss, Jack J.W.A. van Loon, Giovanna Aronne

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

Gravitropism and phototropism play a primary role in orienting root growth. Tropistic responses of roots mediated by gravity and light have been extensively investigated, and a complex mutual interaction occurs between these two tropisms. To date, most studies have been conducted in 1 g, microgravity, or simulated microgravity, whereas no studies investigated root phototropism in hypergravity. Therefore, we studied the effects of several gravity treatments with those of different light wavelengths on root growth orientation. Here, we report growth and curvature of Brassica oleracea roots under different g levels, from simulated microgravity up to 20 g, and unilateral illumination with different spectral treatments provided by light emitting diodes. Microgravity was simulated with a random positioning machine whereas hypergravity conditions were obtained using the Large Diameter Centrifuge at the laboratories of the European Space Agency in the Netherlands. Four light treatments (white light, blue light, red light, and dark) were used in this study. Overall, roots of seedlings grown in the dark were longer than those developed under unilateral light treatments, regardless of the gravity level. Unilateral blue light or white light stimulated a negative phototropism of roots under all g levels, and root curvature was not affected by either hypergravity or simulated microgravity compared to 1 g. Results also confirmed previous findings on the effect of light intensity on root curvature and highlighted the relevance of blue-light photon flux density in root phototropism. Roots illuminated with red light showed a weak curvature in simulated microgravity but not in hypergravity. Moreover, root curvature under red light was similar to dark-grown roots in all g levels, suggesting a possible involvement of surface-dependent phenomena in root skewing under either red light or dark conditions. Further studies can confirm phototropic responses of B. oleracea in the weightless environment of orbiting spacecraft. Nevertheless, according to our findings, directional lighting represents an effective stimulus to guide root growth in a wide range of gravity conditions.

Original languageEnglish
Article number104700
Pages (from-to)1-10
Number of pages10
JournalEnvironmental and Experimental Botany
Volume193
Early online date6 Nov 2021
DOIs
Publication statusPublished - Jan 2022

Bibliographical note

Funding Information:
Authors acknowledge Andrea Buonanno's contribution to create all parts of the ROOTROPS device in CATIA V5. We would also like to thank Mr. Alan Dowson from ESA-ESTEC TEC- MMG LIS Lab for his support in preparation and during this study. This work was supported by the ESA-HRE CORA contract #4000127705/19/NL/PG/pt. Financial support was also provided by ESA-TEC contract #4000116223/16/NL/KML/hh to Jack J.W.A. van Loon, by Spanish Agencia Estatal de Investigacio?n (Grant RTI2018-099309-B-I00, co-funded by EU- ERDF) to F. Javier Medina, and by NASA (Grant 80NSSC17K0546) to John Z. Kiss.

Funding Information:
Authors acknowledge Andrea Buonanno’s contribution to create all parts of the ROOTROPS device in CATIA V5. We would also like to thank Mr. Alan Dowson from ESA-ESTEC TEC- MMG LIS Lab for his support in preparation and during this study. This work was supported by the ESA-HRE CORA contract #4000127705/19/NL/PG/pt . Financial support was also provided by ESA-TEC contract #4000116223/16/NL/KML/hh to Jack J.W.A. van Loon, by Spanish Agencia Estatal de Investigación (Grant RTI2018-099309-B-I00 , co-funded by EU- ERDF) to F. Javier Medina, and by NASA (Grant 80NSSC17K0546 ) to John Z. Kiss.

Publisher Copyright:
© 2021 Elsevier B.V.

Funding

Authors acknowledge Andrea Buonanno's contribution to create all parts of the ROOTROPS device in CATIA V5. We would also like to thank Mr. Alan Dowson from ESA-ESTEC TEC- MMG LIS Lab for his support in preparation and during this study. This work was supported by the ESA-HRE CORA contract #4000127705/19/NL/PG/pt. Financial support was also provided by ESA-TEC contract #4000116223/16/NL/KML/hh to Jack J.W.A. van Loon, by Spanish Agencia Estatal de Investigacio?n (Grant RTI2018-099309-B-I00, co-funded by EU- ERDF) to F. Javier Medina, and by NASA (Grant 80NSSC17K0546) to John Z. Kiss. Authors acknowledge Andrea Buonanno’s contribution to create all parts of the ROOTROPS device in CATIA V5. We would also like to thank Mr. Alan Dowson from ESA-ESTEC TEC- MMG LIS Lab for his support in preparation and during this study. This work was supported by the ESA-HRE CORA contract #4000127705/19/NL/PG/pt . Financial support was also provided by ESA-TEC contract #4000116223/16/NL/KML/hh to Jack J.W.A. van Loon, by Spanish Agencia Estatal de Investigación (Grant RTI2018-099309-B-I00 , co-funded by EU- ERDF) to F. Javier Medina, and by NASA (Grant 80NSSC17K0546 ) to John Z. Kiss.

FundersFunder number
ESA-TEC4000116223/16/NL/KML/hh
National Aeronautics and Space Administration80NSSC17K0546
European Commission
European Space Agency4000127705/19/NL/PG/pt
European Regional Development Fund
Agencia Estatal de InvestigaciónRTI2018-099309-B-I00

    Keywords

    • Blue light
    • Gravitropism
    • Hypergravity
    • Light quality
    • Phototropism
    • Random positioning machine
    • Red light
    • Root tropisms
    • Simulated microgravity

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