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Molecular Plant Breeding 2010, Vol.1 No.1
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region as that reported by Lu et al. (1996)
and
Moncada et al.(2001).
Pleiotropic effect is very common phenomenon in
plant biology that explained as one chromosomal
region conferring two or more traits. Six cases of wild
rice QTL studies using
O. rufipogon
as the donor
parent and different cultivar as the recurrent parent
have been reported that the pleiotropic effect exists
(Xiong et al., 1999; Cai et al., 2002; Thomson et al.,
2003; Lee et al., 2005 ). QTL Clustering of six traits
were found in the region of RM110
-
RM211 on
chromosome 2.. The correlations among those traits
were high significance.. As expected, enhancing rice
yielding capacity would be depend on the increase of
yield related components..
3 Materials and Methods
3.1 Descriptions of parents used in this research
Yuexiangzhan, a launched indica cultivar developed
by Institute of Rice of Guangdong Academy of
Agricultural Sciences in South China, was used as a
recurrent parent. Yuexiangzhan has high harvest index
(up to more than 0.6), low ratio of sheath to blade
length, and high productive tiller capability. The wild
rice accession G52
-
9 (
O.rufipogon
L) collected from
Gaozhou, a county of Guangdong province in China,
was used as a donor parent. G52
-
9 is evergreen rice
around the year without obvious winter dormancy, but
only once heading a year with small panicles, low
seed setting and brown kernels. G52
-
9 is recognized
as elite wild rice germplasm with some desirable traits,
such as strong resistant to diseases and insects as well
as high tolerant to low temperature and low soil
fertility.
3.2 Procedures for developing mapping population
An advanced backcross procedure as described by Tian
(Tian, et al
.
2006) was employed to develop the mapping
population in this research. An individual plant of
G52
-
9 was used as the pollen donor crossing with
Yuexiangzhan to generate F
1
plants. F
1
plants were
backcrossed continuing three times by recurrent
Yuexiangzhan until a BC
3
F
1
population brought out.
All of the individuals derived from BC
3
F
1
were then
selfing continuing three generations upto BC
3
F
3.
Total
of 245 BC
3
F
1
progenies were genotyped with SSR
markers .Hundred and twenty lines randomly selected
from the BC
3
F
3
population were analyzed for detecting
QTLs based on the results of BC
3
F
1
genotyping data,
and for developing introgression lines.
3.3 Agronomic traits and phenotypic evaluation
We conducted the field trials for measuring and
phenotyping the agronomic traits at three different
locations in Guangdong and Hainan in 2007 and 2008.
The 2060 BC
3
F
2
and 2060 BC
3
F
3
lines multiple
derived from the 206 BC
3
F
1
lines selected from 245
BC
3
F
1.
were used for field trials. The 245 BC
3
F
1
, 2060
BC
3
F
3
lines and the recurrent parent,Yuexiangzhan,
were grown at Dafeng Experimental Station of
Guangdong Academy of Agricultural Sciences in
August of 2007 and 2008, respectively. The 2060
BC
3
F
2
was nursed at Hainan Winter Nursing
Experimental Station in Sanya in the winter of 2007..
The protocols for the field trials were followed by the
local rice production management instructions. Each
line with 50 individuals transplanted by 5 rows and 10
individuals each row with a uniform 10 cm×30 cm.
space. A randomized complete block design with two
replications was employed in this field trial.
Twenty plants random sampled in each trial plot at
harvest stage for trait measure and evaluation. BC
3
F
1
families and selected 120 lines in BC
3
F
3
were
phenotyped for yield and yield-related traits, whereas
the recurrent parent used to be as reference. The
evaluated traits were included as follows:
(1) 1000
-
grain weight (1000
-
GW) – the weight of
1000 fully filled grains averaged by five different
panicle in gram, (2) grain number per panicle (GN) -
the mean of five panicles, (3) grain number per plant
(GNP) -the number of filled grain per panicle by
productive panicle number, (4) spikelet number per
panicle (SN) – the number of spikelets (including both
filled and empty ones) averaged from five panicles in
each plant, (5) spikelet number per plant (SNP)-total
number of spikelets (including filled and empty ones)
in each plant calculated as the average number of
spikelets per panicle by the number of productive
tillers, (6) seed setting percentage (SSP)- ratio of grain
number per plant to spikelet number per plant, (7)
productive panicle number (PPN)-total number of