Abscisic acid inhibits germination of Striga seeds and is released by them likely as a rhizospheric signal supporting host infestation

Muhammad Jamil, Yagiz Alagoz, Jian You Wang, Guan Ting Erica Chen, Lamis Berqdar, Najeh M. Kharbatia, Juan C. Moreno, Hendrik N.J. Kuijer, Salim Al-Babili*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Seeds of the root parasitic plant Striga hermonthica undergo a conditioning process under humid and warm environments before germinating in response to host-released stimulants, particularly strigolactones (SLs). The plant hormone abscisic acid (ABA) regulates different growth and developmental processes, and stress response; however, its role during Striga seed germination and early interactions with host plants is under-investigated. Here, we show that ABA inhibited Striga seed germination and that hindering its biosynthesis induced conditioning and germination in unconditioned seeds, which was significantly enhanced by treatment with the SL analog rac-GR24. However, the inhibitory effect of ABA remarkably decreased during conditioning, confirming the loss of sensitivity towards ABA in later developmental stages. ABA measurement showed a substantial reduction of its content during the early conditioning stage and a significant increase upon rac-GR24-triggered germination. We observed this increase also in released seed exudates, which was further confirmed by using the Arabidopsis ABA-reporter GUS marker line. Seed exudates of germinated seeds, containing elevated levels of ABA, impaired the germination of surrounding Striga seeds in vitro and promoted root growth of a rice host towards germinated Striga seeds. Application of ABA as a positive control caused similar effects, indicating its function in Striga/Striga and Striga/host communications. In summary, we show that ABA is an essential player during seed dormancy and germination processes in Striga and acts as a rhizospheric signal likely to support host infestation.

Original languageEnglish (US)
JournalPlant Journal
DOIs
StateAccepted/In press - 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.

Keywords

  • abscisic acid
  • conditioning
  • dormancy
  • fluridone
  • Striga
  • strigolactones

ASJC Scopus subject areas

  • Genetics
  • Plant Science
  • Cell Biology

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