Marker-Assisted Introgression of Major QTLs for Grain Yield Under Drought in Rice - Translational Genomics for Crop Breeding: Abiotic Stress, Yield and Quality - page 62

as our understanding of plant response to stress
increases.
Identifying drought tolerance traits using
major-effect drought yield QTL lines presents
a unique opportunity to explore the traits that are
affecting plant response to drought, with con-
fidence that the differences in traits between
+

ular in respective drought-prone rice-growing
regions. Pyramiding of multiple DTY QTLs,
together with pathogen-resistance genes, is the
next step for meeting the goal of appreciable ( 1

tha − 1 ) yield advantages under drought stress that
could be adopted by farmers.

>

QTL lines have a high proba-
bility of being responsible for differences in
yield. Working with material that is known to
have improved yield under drought and being
able to compare genetically similar germplasm
(

QTL and −

References

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QTL lines) facilitates more rapid
pinpointing of the traits behind the QTLs. Fur-
thermore, this approach allows us to be open-
minded in our understanding of the mecha-
nisms behind drought tolerance; selecting for
yield under drought, as opposed to selecting for
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grain yield under drought.

+ QTL and −

Summary

Recent progress in improving rice yield under
drought through direct selection for yield is ben-
efiting from the efficiency and high-throughput
capacity of molecular strategies. Advancement
of generations while simultaneously applying
drought stress and the use of large ( 300 lines)

populations have been key components of this
progress. Major-effect drought-yield QTLs that
are effective in multiple backgrounds across a
wide range of environments have been identified.
Some of these QTLs are also seen to be con-
tributed from multiple drought-tolerance donor
genotypes. The drought response of physiologi-
cal traits associated with the drought-yield QTLs
has agreed with the yield response to increas-
ing drought stress severity and has pointed
to some novel drought traits. Marker-assisted
backcrossing and the development of BIL and
NIL populations of the drought yield QTLs in
multiple susceptible backgrounds is an efficient
way of improving the drought tolerance of local
varieties whose grain and plant types are pop-

>

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