Abstract:
The parasitic weed Striga hermonthica hampers the production of sorghum, the most important cereal
crop
in
Eritrea.
This
weed
has
a
complex
mode
of
infestation
that
adapts
to
many
hosts
and
environments,
complicating conventional breeding for resistance, which is the only form of crop improvement
available to Eritrean breeders, but has failed. This study aimed at improving resistance against this parasite
by transferring 5 Striga resistant Quantitative Trait Loci (QTLs) from resistance donor N13 to Striga
susceptible Farmer-Preferred Sorghum Variety (FPSV) Hugurtay from Eritrea. The method involved backcrossing
using marker-assisted selection (MAS) and evaluation of the best introgressed lines for Striga
resistance in artificially infested fields. Foreground selection was performed with up to 11 polymorphic
simple
sequence
repeat
(SSR)
markers
linked
to
Striga
resistance
QTLs,
while
background
selection
was
conducted in the BC3F2 generation with 27 polymorphic unlinked SSR markers to identify the best recovery
of the recurrent parent (RP) genetic background. Out of 84 BC3F3 lines, L2P3-B, L1P5-A and L2P5P35
performed best with respect to both grain yield and reduced Striga infestation. These lines were more
resistant to Striga than Hugurtay, but less resistant than N13. The three lines yielded twice as much as N13,
with
Area Under Striga Number Progression Curve (AUSNPC) values on average 18% higher than that of
N13 and 38% lower than that of Hugurtay. This suggests that the introgressed QTLs conferred significant
Striga
resistance
and
yield
advantage
to
these
BC3F3 backcross
progenies
under
Striga
pressure.
These
lines have good potential for future release and demonstrate that when MAS is available to conventional
breeders, even in countries with no genotyping facilities, it is a useful tool for enhancement, expediency
and precision in crop improvement