Agriculture Reference
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neither inhibition nor visible phenotypic alterations despite
constitutive expression of the CBF3 or ABF3, unlike the results
previously obtained from Arbidopsis, where transgenic plants
were stunted (Oh et al. 2005).
Panicle formation is interrupted by low temperature. It is
generally accepted that cold tolerance of rice at one stage is
different from another stage. However, Okabe and Toriyama
(1972) reported that varieties seen to respond similarly to cold
temperature at different growth stages. Some varieties have
been found to be tolerant at different growth stages.
QTLs for cold tolerance related traits at the booting stage
using balanced population for 1525 recombinant inbred lines of
near isogenic lines (viz. NIL-RILs for BC5F3, BC5F4 and BC5F5)
over 3 years and 2 locations by backcrossing the strongly
cold-tolerant (Kunming X Iaobaigu) and a cold sensitive
cultivar (Towada) was analyzed. 676 microsatellite markers
were employed to identify QTLs conferring cold tolerance at
booting stage. Single marker analysis revealed that 12 markers
were associated with cold tolerance on chromosome 1, 4 and 5.
Using a LOD signifi cance threshold of 3.0 compositive interval
mapping based on a mixed linear model revealed eight QTLs
for 10 cold tolerance-related traits on chromosomes 1, 4 and 5.
They were tentatively designated qCTB-1-1, qCTB-4-1, qCTB-
4-2, qCTB-4-3, qCTB-4-4, qCTB-4-5, qCTB-4-6 and qCTB-5-1.
Their marker intervals were narrowed to 0.3-6.8 cM. Genetic
distances between the peaks of the QTL and nearest markers
varied from 0 to 0.04 cM. It is noticed in some traits associated
with cold tolerance such as QCTB-1-1 for 5 traits (plant height,
panicle exsertion, spike length, blighted grains per spike, and
spikelet sterility), qCTB-4-1 for 8 traits (plant height, node
length under spike, leaf length, leaf width, spike length, full
grains per spike, total grains per spike and spikelet sterility),
