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Research Article
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Witchweeds (Striga spp.) greatly limit production of Africa’s most staple crops. These parasitic plants use strigolactones (SLs) – chemical germination stimulants, emitted from host’s roots to germinate, and locate their hosts for invasion. This information exchange provides opportunities for controlling the parasite by either stimulating parasite seed germination without a host (suicidal germination) or by inhibiting parasite seed germination (pre-attachment resistance). We sought to determine genetic factors that underpin Striga pre-attachment resistance in sorghum using the genome wide association study (GWAS) approach. Results revealed that Striga germination was associated with genes encoding hormone signaling functions e.g., the Novel interactor of jaz (NINJA) and, Abscisic acid-insensitive 5 (ABI5). This pointed toward abscisic acid (ABA) and gibberellic acid (GA) as probable determinants of Striga germination. To test this hypothesis, we conditioned Striga using: ABA, ABA + its inhibitor fluridone (FLU), GA or water. Unexpectedly, Striga conditioned with FLU germinated after 4 days without SL. Upon germination stimulation using sorghum root exudate or the synthetic SL GR24, we found that ABA conditioned seeds had above 20-fold reduction in germination. Conversely, FLU conditioned seeds recorded above 20-fold increase in germination and conditioning with GA caused at least 1.5-fold reduction in Striga seed germination. Germination assays using seeds of a related parasitic plant (Alectra vogelii) showed similar degrees of stimulation and reduction of germination by the hormones further affirming the hormonal crosstalk. Our findings have far-reaching implications in the control of some of the most noxious pathogens of crops in Africa.
Keywords
abscisic acid, gibberellic acid GWAS, hormonal crosstalk, parasitic plants, pre-attachment resistance, sorghum, Striga, strigolactone
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This is a list of supplementary files associated with this preprint. Click to download.
- SupplFig.S1.tif
Supplementary file1 Suppl. Fig. S1 Geographic origins of the sorghum used in the GWAS study. Categories are based on the major sorghum races.
- SupplFig.S2.tif
Supplementary file2 Suppl Fig. 2 Bayesian Information Criterion (BIC) identification of optimal K clustering. The lowest K (K=8) is indicated by an elbow curve of BIC values.
- SupplFig.S3.tif
Supplementary file3 Suppl Fig. S3 Hierarchical Bayesian clustering of sorghum accessions used in the GWAS study using various K values K=7; (CV=0.35293 ) K = 8 (CV=0.35673) and K = 9 (CV=0.36229).
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This is a preprint, a preliminary version of a manuscript that has not completed peer review at a journal. Research Square does not conduct peer review prior to posting preprints. The posting of a preprint on this server should not be interpreted as an endorsement of its validity or suitability for dissemination as established information or for guiding clinical practice.
Research Article
Badges
Prescreen
This manuscript passed our Prescreen assessment
Complete author information
Appropriate declaration statements
Potential risks to human health
Prescreen
History
CURRENT STATUS: Posted
Version 1
Posted 25 Oct, 2021
No community comments so far
Metrics
Comments: 0
PDF Downloads: ...
HTML Views: ...
Subject Areas
Plant Molecular Biology and Genetics
License:
This work is licensed under a CC BY 4.0 License. Read Full License
Witchweeds (Striga spp.) greatly limit production of Africa’s most staple crops. These parasitic plants use strigolactones (SLs) – chemical germination stimulants, emitted from host’s roots to germinate, and locate their hosts for invasion. This information exchange provides opportunities for controlling the parasite by either stimulating parasite seed germination without a host (suicidal germination) or by inhibiting parasite seed germination (pre-attachment resistance). We sought to determine genetic factors that underpin Striga pre-attachment resistance in sorghum using the genome wide association study (GWAS) approach. Results revealed that Striga germination was associated with genes encoding hormone signaling functions e.g., the Novel interactor of jaz (NINJA) and, Abscisic acid-insensitive 5 (ABI5). This pointed toward abscisic acid (ABA) and gibberellic acid (GA) as probable determinants of Striga germination. To test this hypothesis, we conditioned Striga using: ABA, ABA + its inhibitor fluridone (FLU), GA or water. Unexpectedly, Striga conditioned with FLU germinated after 4 days without SL. Upon germination stimulation using sorghum root exudate or the synthetic SL GR24, we found that ABA conditioned seeds had above 20-fold reduction in germination. Conversely, FLU conditioned seeds recorded above 20-fold increase in germination and conditioning with GA caused at least 1.5-fold reduction in Striga seed germination. Germination assays using seeds of a related parasitic plant (Alectra vogelii) showed similar degrees of stimulation and reduction of germination by the hormones further affirming the hormonal crosstalk. Our findings have far-reaching implications in the control of some of the most noxious pathogens of crops in Africa.
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
This is a list of supplementary files associated with this preprint. Click to download.
- SupplFig.S1.tif
Supplementary file1 Suppl. Fig. S1 Geographic origins of the sorghum used in the GWAS study. Categories are based on the major sorghum races.
- SupplFig.S2.tif
Supplementary file2 Suppl Fig. 2 Bayesian Information Criterion (BIC) identification of optimal K clustering. The lowest K (K=8) is indicated by an elbow curve of BIC values.
- SupplFig.S3.tif
Supplementary file3 Suppl Fig. S3 Hierarchical Bayesian clustering of sorghum accessions used in the GWAS study using various K values K=7; (CV=0.35293 ) K = 8 (CV=0.35673) and K = 9 (CV=0.36229).
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