Gibberellins Promote Seed Conditioning by Up-Regulating Strigolactone Receptors in the Parasitic Plant Striga hermonthica.

Jia Xin Yap, Yuichiro Tsuchiya

Plant & cell physiology 2023 Sep 15

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Dormant seeds of the root parasitic plant Striga hermonthica sense strigolactones from host plants as environmental cues for germination. This process is mediated by a diversified member of the strigolactone receptors encoded by HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE2 genes. It is known that warm and moist treatment during seed conditioning gradually makes dormant Striga seeds competent to respond to strigolactones, although the mechanism behind it is poorly understood. In this report, we show that plant hormone gibberellins increase strigolactone competence by up-regulating mRNA expression of the major strigolactone receptors during the conditioning period. This idea was supported by a poor germination phenotype in which gibberellin biosynthesis was depleted by paclobutrazol during conditioning. Moreover, live imaging with a fluorogenic strigolactone mimic, yoshimulactone green W, revealed that paclobutrazol treatment during conditioning caused aberrant dynamics of strigolactone perception after germination. These observations revealed an indirect role of gibberellins in seed germination in Striga, which contrasts with their roles as dominant germination-stimulating hormones in non-parasitic plants. We propose a model of how the role of gibberellins became indirect during the evolution of parasitism in plants. Our work also highlights the potential role for gibberellins in field applications, for instance, in elevating the sensitivity of seeds toward strigolactones in the current suicidal germination approach to alleviate the agricultural threats caused by this parasite in Africa. © The Author(s) 2023. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Citation

Jia Xin Yap, Yuichiro Tsuchiya. Gibberellins Promote Seed Conditioning by Up-Regulating Strigolactone Receptors in the Parasitic Plant Striga hermonthica. Plant & cell physiology. 2023 Sep 15;64(9):1021-1033