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Molecular Plant Breeding 2011, Vol.2, No.1, 1
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(Zhang et al., 1996). Shuhui527 which is a key restorer
line, was bred between 1318 and 88R3360 (Wang et
al., 2004). Both of them are Indica restorer lines with
good combining ability and strong restoring ability. In
present study, an average of 5.04 allelic genes were
detected in each pair and the diversity index was 0.624,
which were generally higher than others. The similarity
coefficients between two recurrent parents and Japonic
rices were low and that with Indica rices were relatively
high. The similarity coefficients between Shuhui527
and Indica rices were generally higher than that
between Minghui86 and Indica rices. This result could
be verified with breeding pedigree of two recurrent
parents. The similarity coefficients in this study are
relatively high, which is consist with recent reports
(Duan et al., 2001; Huang et al., 2006).
Using SSR molecular markers, the result obtained
from UPGMA clustering indicated test materials
could be divided into japonic and indica rices. Pusa,
Domsiah, Milagrosa and BJ1 differed a lot from other
cultivars. Genetic diversity and relationship could be
tested through similarity coefficients at molecular
level. SSR polymorphism detection could be used as
one of efficient and accurate method for genetic
diversity study. It will provide important information
for identification of cultivars and construction of core
germplasm. In addition, this research will provide
important theoretical basis for the future study of rice
genetic evaluation and parents’ selection.
Genetic diversity and relationship analysis makes
efficient references for large-scale exploration of
favorable gene/QTL. The objective of this research
comprise of enlarged genetic basis for recurrent
parents, efficiently resistance to all kinds of biotic and
abiotic stresses and development of newly-bred
cultivars with desirable characters. Nevertheless,
genetic relationship is not the only criterion for
selection of parent plants due to the difference in the
types of population and breeding targets. Hybridization,
between dwarfing plants with good performance and
another elite with the same or similar ecotype but
different relationship, usually perform well, which is a
basic experience for selection of parents in indica
dwarfing breeding in China. (Pang et al., 1994) In
general, it can be more fast to develop a promising
variety using elite parents with close relationship due
to good characters and more favorable genes. However,
agriculture productivity demands comprehensive
varieties, which push on enlarged genetic basis with
more favorable genes. Obviously, combination
between cultivars from distant relationship will easily
get seperation, thus less individuals with good
characters will be obtained, hereby the conventional
hybridization can’t work well. Forturately, the conflict
could be solved with advanced backcross introgression,
proposed in the program of global rice molecular
breeding in 1998, by introducing favorable genes into
the same genetic background from closely related
varieties, distant subspecies or even wild varieties.
Subsequently, the promising varieties can be developed
by pyramiding sister lines with favorable targeted
genes from different donors but similar genetic
background (Li et al., 2005). This research demonstrated
desirable cultivars with similar relationship could be
used for improving recurrent parents, which will
contribute to hybridaztion success in a short period. On
the other hand, those with bad characters and distant
relationship could be used for backcrosses for several
times to explore specific favorable genes. Furthermore,
the ingrossed lines with different favorable genes can
be pyramid to an elite genetic background of recurrent
parents to develop novel restorer lines with great
improvement in several targets traits.
Reference
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