Molecular Plant Breeding 2016, Vol.7, No.33, 1
-
15
9
already converted to the RP genome except for chromosomes 1, 6, 8, and 11. Parallel to the results reported by
Suh et al. ( Suh et al., 2009) donor-derived segments were also prevalent in chromosome 6 and can be attributed to
the foreground genotyping analysis for
Pi40
. These results clearly indicate the applicability of these new
technologies in rice molecular breeding.
The main agronomic traits of selected ABLs were mostly similar to Osmancık-97 and Halilbey. However, some of
the selected plants showed increase in plant height which may be either due to the transfer of some QTLs from the
donor causing increase of plant height or the soil and other climatic conditions in the Philippines. The ABLs
possess strong resistance to blast with similar phenotype of the recurrent parents. Our results indicate the
advantage of using genotype and phenotype selections in early backcross generations such as BC
3
or BC
4
to
produce ABLs having desirable agronomic traits and resistance to blast. Breeding lines were also selected with
BPH resistance gene,
Bph18
,
at early backcross generation (BC
2
/BC
3
) using marker-assisted backcross breeding
without linkage drag (Suh et al., 2011).
The incorporation of a novel broad-spectrum blast resistance gene,
Pi40
into elite rice cultivars is considered as an
effective, economical and environment friendly breeding strategy to control the disease for stable rice production.
This is the first study on the introduction of a new blast resistance gene,
Pi40
, into the elite japonica cultivars,
Osmancık-97 and Halilbey, using DNA marker-assisted backcross breeding methods. Based on agronomic traits
analysis, our results showed that advanced backcross progenies had desirable phenotypes of the recurrent parents,
Osmancık-97 and Halilbey. Foreground selection using the
Pi40
gene specific markers could isolate early
generation selected backcross progeny lines with strong resistance to blast disease. Therefore, the transfer of
Pi40
gene into Turkish cultivars is an effective strategy to improve the elite cultivars of Turkey. Further studies on
hotspot locations screening of selected backcross lines will identify promising genotypes with blast resistance to
develop new cultivars for Turkey.
3 Conclusion
Revealing the presence of the durable broad-spectrum resistance gene,
Pi40
, for blast in elite Turkish cultivars
showed that marker-assisted backcrossing is an effective tool to develop and improve the cultivars, Osmancik-97
and Halilbey. Advanced genomics technology such as 6K SNP genotyping and automated capillary
electrophoresis analysis of the promising lines were used to carry out genotyping of selected breeding lines
possessing blast resistance, high yield potential and desirable grain quality. The
Pi40
blast
resistance gene will
enhance rice production and productivity in the temperate regions of the world and will be highly useful in other
breeding programs.
4 Materials and Methods
4.1 Plant materials
Two elite cultivars of Turkey, Osmancık-97 and Halilbey, were used as RP, and IR83260-1-1-1-5-B-3-1-2-B
carrying the
Pi40
gene was used as DP. Eleven ABLs of BC
3
F
5.6
and BC
4
F
5.6
generations were also used in this study.
The development of F
1
and production of early backcross generation progenies (Figure 3) were conducted in Rural
Development Administration (RDA) in South Korea in 2011 and the rest of the crosses and advancement of the
progenies were continued at the Plant Breeding (PB) Division of the International Rice Research Institute (IRRI),
Los Baños, Laguna, Philippines. The seeds of Turkish cultivars were obtained from Trakya Agricultural Research
Institute (TARI), Edirne, Turkey. Seeds of the varieties CO39, IR42, IR50, IR72, IR65482-4-136-2-2 (
Pi40
) and
Lijiangxintuanheigu (LTH) used as checks and spreader rows in the blast nursery test were obtained from PB
division of IRRI.
4.2 Molecular Analysis
4.2.1 DNA extraction
Young leaves collected from 14 day-old seedlings were lyophilized in Alpha 1-4 LD-2 Freeze dryer (Martin Christ,
Germany) for 72 hours at -80ºC. Leaf samples were finely cut and ground in Geno-Grinder 2010 (SPEX Sample
