Abstract
Societal Impact Statement The root‐parasitic plant Striga hermonthica can cause severe crop failure, leading to significant agricultural and economic losses in Africa. Despite the promising target offered by the Striga seed germination mechanism for developing control methods, effective control methods have yet to be established. For seed germination, Striga must undergo an incubation under warm and humid conditions, a process termed conditioning, which allows it to germinate. Here, we report that the plant hormone gibberellin stimulates the conditioning process in Striga seeds. Our findings suggest that the quantitative control of gibberellin in plants is a promising approach for controlling Striga infestations and may help alleviate substantial threats to food security. Summary The root‐parasitic plant S. hermonthica is a serious agricultural threat in Africa. Although a number of control methods have been employed to combat Striga , there is still a need to develop more effective control methods. Striga seeds germinate only in the presence of host plants, owing to the need for host‐released stimulants, primarily strigolactone. To detect signals from the host, Striga seeds must be exposed to a specific warm, dark, and moist environment, which is known as conditioning. Gibberellin directly promotes germination in many nonparasitic plants, but Striga seeds are insensitive to exogenous gibberellin. Consequently, the role of gibberellin in the germination of Striga seeds is unclear. We demonstrated that the effect of the gibberellin biosynthesis inhibitor paclobutrazol was higher in seeds during the conditioning, compared with those already conditioned, suggesting that gibberellin primarily regulates conditioning rather than germination. The content of an active form gibberellin, gibberellin A4 (GA 4 ) exhibited an increase throughout the conditioning period, and we quantified the elevated expression levels of some gibberellin biosynthesis genes. The GA 4 treatment shortened the conditioning period required for strigolactone‐induced seed germination. We also discovered that gibberellin upregulated ShACO1 , the gene responsible for ethylene synthesis, during conditioning, and that the inhibition of GR24‐induced germination by the ethylene biosynthesis inhibitor α‐aminoisobutyric acid was gradually alleviated by GA 4 . Our findings demonstrate that gibberellin is critical for conditioning and germination processes but acts as a minor stimulant in Striga seeds. This study demonstrates the potential of quantitative endogenous gibberellin control for Striga management, providing valuable insights for alleviating food security issues.
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Claims 8
Claim · model-written summary
Paclobutrazol affected Striga seeds more during conditioning than after conditioning.
- Taxon
- Striga hermonthica
Striga hermonthicae1 - Treatment
- paclobutrazole0
- Outcome
- effect of the gibberellin biosynthesis inhibitor paclobutrazole0
- Direction
- highere0
- Comparator
- those already conditionede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the effect of the gibberellin biosynthesis inhibitor paclobutrazol was higher in seeds during the conditioning, compared with those already conditioned”
e1“Striga hermonthica”
Claim · model-written summary
GA4 content rose across Striga seed conditioning.
- Taxon
- Striga hermonthicaStriga hermonthicae1
- Organ / stage
- conditioning periode0
- Outcome
- content of an active form gibberellin, gibberellin A4 (GA 4 )e0
- Direction
- increasee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The content of an active form gibberellin, gibberellin A4 (GA 4 ) exhibited an increase throughout the conditioning period”
e1“Striga hermonthica”
Claim · model-written summary
Some gibberellin biosynthesis genes showed elevated expression during Striga conditioning.
- Taxon
- Striga hermonthicaStriga hermonthicae1
- Gene
- gibberellin biosynthesis genese0
- Outcome
- expression levelse0
- Direction
- elevatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we quantified the elevated expression levels of some gibberellin biosynthesis genes.”
e1“Striga hermonthica”
Claim · model-written summary
GA4 treatment shortened the conditioning needed for strigolactone-induced Striga germination.
- Taxon
- Striga hermonthicaStriga hermonthicae1
- Treatment
- GA 4 treatmente0
- Outcome
- conditioning period required for strigolactone‐induced seed germinatione0
- Direction
- shortenede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The GA 4 treatment shortened the conditioning period required for strigolactone‐induced seed germination.”
e1“Striga hermonthica”
Claim · model-written summary
Gibberellin upregulated the Striga ethylene synthesis gene ShACO1 during conditioning.
- Taxon
- Striga hermonthicaStriga hermonthicae1
- Treatment
- gibberelline0
- Gene
- ShACO1e0
- Outcome
- ShACO1e0
- Direction
- upregulatede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“gibberellin upregulated ShACO1 , the gene responsible for ethylene synthesis, during conditioning”
e1“Striga hermonthica”
Claim · model-written summary
GA4 gradually alleviated inhibition of Striga GR24-induced germination by an ethylene biosynthesis inhibitor.
- Taxon
- Striga hermonthicaStriga hermonthicae1
- Treatment
- GA 4e0
- Outcome
- inhibition of GR24‐induced germinatione0
- Direction
- alleviatede0
- Comparator
- ethylene biosynthesis inhibitor α‐aminoisobutyric acide0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the inhibition of GR24‐induced germination by the ethylene biosynthesis inhibitor α‐aminoisobutyric acid was gradually alleviated by GA 4 .”
e1“Striga hermonthica”
Claim · model-written summary
The authors conclude gibberellin is critical for conditioning and germination but only a minor Striga germination stimulant.
StrigaOrganisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“gibberellin is critical for conditioning and germination processes but acts as a minor stimulant in Striga seeds.”
Claim · model-written summary
The authors propose control of endogenous gibberellin as a Striga management strategy.
- Outcome
- quantitative endogenous gibberellin control for Striga managemente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“potential of quantitative endogenous gibberellin control for Striga management”