Figure Legends
Figure 1: Genetic structure of the sorghum accession panel (SAP): (a)Striga hermonthica range in Africa overlapping with sorghum
origin (b) A distribution map showing the collection points of sorghum
(174 georeferenced samples collection from Africa) genotypes, races are
represented by color-coded dots (c) Phylogenetic relatedness of 373
sorghum accessions measured by Neighbor-joining technique. Phylogenetic
tree nodes are color coded according to sorghum races.
Figure 2: Identification and characterization of new low
germination stimulant 1 (lgs1 ) sorghum. (a) Sulfotransferase
marker analysis of the lgs1 loci. Presence of a single band
characterized by a 223bp PCR product indicates the presence of the
resistance allele (lgs1 ) (b) Liquid Chromatography Tandem-Mass
Spectrometry (LC-MS/MS) quantification of strigolactones: (upper panel)
orobanchol and 5-deoxystrigol peaks of some representative sorghum lines
in LC-MS/MS analysis (lower panel) Orobanchol and 5-deoxystrigol mass
transitions. (c) Orobanchol quantification (pg per sample) in various
sorghum lines. (d) 5-Deoxystrigol quantification (pg per sample) in
sorghum lines. The strigolactones collected from the root exudates of
various sorghum lines quantified through LC-MS analysis. Data means±SE
(n=6). The treatments with various letters denote significance (one-way
ANOVA, Tukey’s post hoc test, P <0.05). (e) Strigolactone
proportion of SAP lines. LGS1 genotypes had high proportions of
5-deoxystrigol. In contrast, lgs1 genotypes had high proportions
of orobanchol.
Figure 3: Striga resistance in SAP low germination
stimulant 1 sorghum (a) Bioassay to measure Striga resistance by
germination frequency induced by root exudates of resistant (blue, SAPlgs1-1 ) and susceptible (orange, SAP LGS1). (b) Measurement ofStriga germination using germination frequency showing low
germination stimulation in most SAP lgs1 -1 accessions. (c) Agar
gel assay to measure Striga stimulation activity by sorghum rootsin vitro . (d) Measurement of Striga emergence using pot
experiments. Most lsg1 genotypes had a low number ofStriga attachments. (e) Striga emergence pot experiments.
Notable low emergence was observed in most lgs1 lines and in the
LGS1 line PI6506054.
Figure 4: Performance of SAP low germination stimulant 1 sorghum
under natural Striga infestation. (a) Striga emergence
measured as area under Striga number progressive curve (AUSNPC)
at 98 after planting (b) Correlation of Striga emergence (AUSNPC)
at 98 days after planting with relative yield loss as a measure of
sorghum tolerance (c) Heatmap showing Striga resistance levels of
sorghum genotypes based on ranked summation index (RSI) of yield, days
to 50 % flowering and emergence counts. (d) Striga resistance
phenotypes. Wild type LGS1 sorghum with high number of emergedStriga seedlings growing next to lgs1 mutant in aStriga hermonthica infested field in Alupe, western Kenya.Striga resistance evaluation of SAP lgs1 genotypes showed
that here was notable infestation on SAP LGS1 PI533839 but not in
one of the Striga resistant SAP lgs1 genotype PI561071.