Reference "Upland rice grown in soil-filled chambers and exposed to contrasting water-deficit regimes II. Mapping quantitative trait loci for root morphology and distribution."

Reference ID

7780

Title

Upland rice grown in soil-filled chambers and exposed to contrasting water-deficit regimes II. Mapping quantitative trait loci for root morphology and distribution.

Source

Field-Crops-Research, 2002, vol. 76, pp. 25-43

Authors (4)

Price-A-H	Steele-K-A
Moore-B-J	Jones-R-G-W

Abstract

Root morphological characteristics are known to be important in the drought
resistance of some rice (Oryza sativa L.) varieties. The identification of
quantitative trait loci (QTLs) associated with root morphology and other drought
resistance-related traits should help breeders produce more drought resistant
varieties. Stability in the expression of root growth QTL across rooting
environments is critical for their use in breeding programs. A greenhouse
experiment in which a mapping population of 140 recombinant inbred lines and the
parental varieties Bala and Azucena were grown in glass-sided soil chambers and
evaluated for root growth and water uptake was conducted. In each of 2 years,
two treatments were used; an early water-deficit (WD0) in which seeds were sown
into wet soil but received no more water, and a late water-deficit (WD49) in
which the plants were watered for 49 days and then received no water for a week.
The major differences between treatments and years in dry matter partitioning
and root growth traits are reported elsewhere. Here, the identification of QTLs
for root growth traits by composite interval mapping is described. At LOD>3.2,
there were six QTLs for the weight of roots below 90 cm and maximum root length,
11 for root to shoot ratio, 12 for the number of roots past 100 cm, and 14 for
root thickness. A total of 24 regions were identified as containing QTLs (these
regions often contained several QTLs identified for different root traits). Some
were revealed only in individual experiments and/or for individual traits, while
others were common to different traits or experiments. Seven QTLs, on
chromosomes 1, 2, 4, 7, 9 (two QTLs) and 11, where considered particularly
noteworthy. The complex results are discussed in the context of previously
reported QTLs for root growth in other populations, the interaction between QTL
with the environment and the value of QTLs for breeding.