Abstract:
Aegilops speltoides is an important genetic
resource for wheat improvement and has high levels of
heat tolerance. A heat-tolerant accession of Ae. speltoides
pau3809 was crossed with Triticum durum cv.
PDW274, and BC2F4-6 backcross introgression lines
(BILs) were developed, phenotyped for important
physiological traits, genotyped using SSR markers and
used for mapping the QTL governing heat tolerance
component traits. A set of 90 BILs was selected from
preliminary evaluation of a broader set of 262 BILs
under heat stress. Phenotyping was conducted for
physiological traits such as cell membrane thermostability,
chlorophyll content, acquired thermotolerance,
canopy temperature and stay green. Much variation for
these traits was observed in random as well as selected
sets of BILs, and comparison of the BILs with the
recurrent parent showed improvement for these traits
under normal aswell as heat stress conditions, indicating
that introgressions fromAe. speltoides might have led to
the improvement in the heat tolerance potential of the
BILs. Introgression profiling of the 90 BILs using SSR
markers identified Ae. speltoides introgression on all the
14 chromosomes with introgressions observed on A as
well as B genome chromosomes. QTL mapping identified
loci for various heat tolerance component traits on
chromosomes 2B, 3A, 3B, 5A, 5B and 7A at significant
LOD scores and with phenotypic contributions varying
from 11.1 to 28.7 % for different traits. The heattolerant
BILs and QTL reported in the present study
form a potential resource that can be used for wheat
germplasm enhancement for heat stress tolerance.
