Page 5 - Rice Genomics and Genetics

Rice Genomics and Genetics 2012, Vol.3, No.3, 13-18
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between SSR markers RM144 was 6.8 cM. While the
genetic distance between the rice SSR markers
RM224 and RM144 was 5.7 cM (Liu et al., 2003b).
By estimate, the physical distance between Pi1 gene
and SSR markers RM144 and RFLP markers RZ536
were 57 kb and 72 kb, respectively. The genetic distance
from SSR marker MRG4766 to Pil was 1.3 cM (Chen
et al., 2005). Using the above three of closely linked
SSR markers of rice blast resistance genes Pi1, the
identification of Pi1 had been detected among 49 rice
varieties (lines) collected from Heilongjiang Province,
and cleared the distribution of Pi1 in the major rice
cultivars in Heilongjiang Province (He et al., 2006).
SSR markers of Pi1 gene used as a tool in
molecular-assisted breeding, and found the results
have better accuracy (Yao et al., 2010).
Pi1 gene molecular marker assisted selection (MAS)
has been effectively applied in breeding program.
Three rice blast resistance genes (Pi1, Pi2, Pi4) has
polymerized via MAS technology by Yang et al (1994).
Hittalmani et al (2000) successfully polymerizatied three
blast resistance genes Pi1, Pi5, Pita by used of MAS
technology. Liu et al (2003a) polymerizated the Pi2,
Pi3 , Pil , Pi3 , the resistance was confirmed by
inoculation of rice blast fungus, and found that
polymerization genes can effectively enhance the rice
resistance to rice blast fungus.
There were collected and conserved about 6,000 rice
resources in Yunnan Province, among these ancient
landraces, some of them were continuous planted near
one century in the same area, and still showed
resistance to rice blast (Liang et al., 2001). In Yunnan
Province, topography, climate and cultivation methods
are various, as well as the physiological rice of rice
blast fungus is diverse. The rice varieties and the rice
diseases were co-evolution in fields, there may be
harboring the novel resistance genes and durable
resistance to rice blast fungus in landraces (Liang et
al., 2001).
In this paper, we will identify the Pi1 gene by using
the SSR markers MRG4766 linked with Pi1 gene of
landraces collected in Yunnan, to make clear the
distribution of Pi1 gene in Yunnan province of China,
and provide the useful information for mining and
utilization of Pi1 gene in rice blast resistance breeding
and production.
1 Result and Analysis
1.1 Genotype of Pi1 detected by molecule marker
and the confirmation of resistance
The genomic DNA of 173 landraces were PCR
amplified by using SSR markers MRG4766, the PCR
products were separated by 8% non-denaturing
polyacrylamide gel electrophoresis, and developed by
silver staining after electrophoresis. PCR validation
results showed that bands with different fragment size
can be distinguished by polyacrylamide gel electrophoresis
(Figure 1), the susceptible variety Lijiangxintuanheigu
without Pi1 gene can be amplified a small fragment
(Figure 1, lane 1). The results were the same with the
previous research by Chen et al (2005), the PCR
products of the landraces were the larger fragments
containing Pi1 gene, whereas, that of the landraces
were the small fragments without Pi1 gene.
Figure 1 Genotype profile of Pi1generated by primer MRG4766
among 30 rice landraces
Note: Lane 1 to 30 is the landrace of Lijiangxintuanheigu,
Changmaogu, Zinuo, Damaxiangu, Ermaxiangu, Huipizinuo,
Ximenggu, Hongmihanwodian, Qianxiangu, Dabainuo,
Banbianzhan, Xiaojiugu, Mabiangu, Shoutiangu, Heiguzi,
Fuerdiao, Jinboyin, Zhenbai 18, Hongmimazhan,
Honggu(Qiusi), Hongkelaoshuya, Haohuanlang, Haoganduo,
Haofengrao, Haomengnan, Haosuoxi, Haoanre, Haonuonao,
Yingnuo and Heiminuo, respectively
In order to confirm the accuracy of the results by SSR
markers detected, thirty landraces (17 with small
fragment, 13 with larger fragment) were selected for
artificial inoculated rice blast isolates 96-2-2b
(AVR-Pi1) at seedling stage in greenhouse, Lijiangxi-
ntuanheigu as susceptible varieties control. The results
showed that Lijiangxintuanheigu and the landraces
with a small fragment were all susceptible, whereas,
the landraces with large fragment were all resistant to
96-2-2b. The inoculation results were entirely consistent
with the results of PCR detection, which demonstrated
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