Sapogenin aglycone
peaks identified in switchgrass extracts are
quantified by GC–MS. (A) +(CI) GC–MS TICs of the diosgenin
standard (black), Dacotah leaf and root (blue), and Alamo leaf root
(red). The identified sapogenin aglycone peaks in the switchgrass
and standard samples are indicated and aligned by the dashed lines.
Zoomed-in views for the peak O2 in the Dacotah root and Alamo root
are indicated by the arrows. (B) Comparison of the total sapogenin
concentrations among the five tissue types for each switchgrass cultivar
(Kruskal–Wallis test: p = 0.012, 0.026, 0.009,
0.024, 0.017, and 0.011 for Dacotach, Summer, Cave-in-Rock, Alamo,
Kanlow, and BoMaster, respectively). LB, leaf blade; LS, leaf sheath,
St, stem; Rhi, rhizome; and Rt, root. (C) Comparison of the total
sapogenin among the six switchgrass cultivars in the leaf blade (Kruskal–Wallis
test: p = 0.766) and root (Kruskal–Wallis
test, p = 0.016). Different lower-case letters on
top of the boxes designate statistically different means (post-hoc
test: Dunn’s test). (D) Ratio of the individual sapogenins
in the leaf blade (upper) and root (lower) of upland and lowland ecotypes.
Heights of the bars reflect the means of the nine replicates (three
cultivars × three replicates) for each ecotype; error bars show
the standard error of the mean; ** standards for 0.001 ≤ p ≤ 0.01 and *** standards for p < 0.001 (one-tailed t-test).