全 文 ： ACTA AGRONOMICA SINICA 2008, 34(1): 100−105 http://www.chinacrops.org/zwxb/
ISSN 0496-3490; CODEN TSHPA9 E-mail: xbzw@chinajournal.net.cn

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 (2006GB2C300117); (06003010B)
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%&(Corresponding author):

()*#E-mail: yjianbo@263.net
Received(+,-.): 2007-04-23; Accepted(/0-.): 2007-07-31.
DOI: 10.3724/SP.J.1006.2008.00100
  
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Developing Rice Lines Resistant to Bacterial Blight and Blast with
Molecular Marker-Assisted Selection
NI Da-Hu1, YI Cheng-Xin1, LI Li1, WANG Xiu-Feng1, ZHANG Yi1, ZHAO Kai-Jun2, WANG
Chun-Lian2, ZHANG Qi2, WANG Wen-Xiang3, and YANG Jian-Bo 1,*
(1 Rice Research Institute, Anhui Academy of Agricultural Sciences, Hefei 230031, Anhui; 2 Institute of Crop Sciences, Chinese Academy of Agricultural
Sciences/National Key Facility for Gene Resources and Genetic Improvement, Beijing 100081; 3 Plant Protection Institute, Anhui Academy of Agricultural
Sciences, Hefei 230031, Anhui, China)
Abstract: The bacterial blight (BB) and blast are two major diseases of rice. Through Molecular Marker-assisted Selection
(MAS) and traditional breeding methods, hybridization and selfcross, blast resistance gene Pi9(t), BB resistant genes Xa21 and
Xa23 were put together. Four stable lines L17–L20 which conferred 3 homozygous resistance genes and good agronomic charac-
teristics were obtained through consecutive inoculation in the field or/and greenhouse, MAS and selection from agricultural as-
pects. By artificial inoculation of 20 blast isolates which came from different countries and areas, 7 Chinese epidemic bacterial
blight races and an Anhui epidemic BB race in the field or/and greenhouse, 4 lines expressed resistance to blast and BB. L17–L20
had high resistance to all 20 blast isolates and showed similar resistant level to and same resistant spectrum as donor variety
75-1-127. At the same time, lines L17–L20 had similar resistance and spectrum to Xa23 gene both in seedling and heading stages.
In the adult stage, the lines had better BB resistance than donor parents M12 with Xa21 gene and CBB23 with Xa23 gene. Using
multi-PCR, gene Pi9(t) and Xa21 can be selected at the same time so that improves the selection efficiency.
Keywords: Bacterial blight; Blast; Gene Pi9(t); Gene Xa21; Gene Xa23; molecular market-assisted selection; Multi-PCR
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Table 1 Resistance of the parents and elite lines to isolates
 Variety


Isolate

Origin 75-1-127 M12 CBB23 L17 (9,21,23)
L18
(9,21,23)
L19
(9,21,23)
L20
(9,21,23)
GUY11  France R(2) S(5) S(7) R(1) R(1) R(3) R(2)
05-032  China R(1) S(6) S(7) R(0) R(1) R(1) R(0)
78334ZA27  China R(0) S(7) S(5) R(1) R(0) R(2) R(2)
Zhao tan  China R(1) S(7) S(7) R(1) R(1) R(1) R(1)
108ZC  China R(2) R(3) R(3) R(1) R(1) R(1) R(1)
Qian shan  China R(2) R(3) S(7) R(2) R(1) R(2) R(1)
ZC13  China R(1) R(2) S(5) R(2) R(2) R(0) R(0)
 1018-14-1 Zhong1018-14-1  China R(1) S(5) S(7) R(1) R(2) R(2) R(0)
B13001-44-1  China R(2) R(3) R(3) R(1) R(1) R(0) R(0)
97102-2  China R(1) S(5) S(4) R(2) R(2) R(1) R(1)
108ZB  China R(1) S(5) S(5) R(2) R(1) R(2) R(1)
ML-8  Mali R(1) S(5) S(7) R(0) R(1) R(1) R(1)
G1001-27-2-2  China R(2) S(5) R(3) R(0) R(1) R(2) R(0)
E1001-33-1-3  China R(0) R(2) R(2) R(1) R(1) R(1) R(1)
D303-010-4  China R(1) S(5) S(5) R(1) R(2) R(2) R(0)
ML-25  Mali R(1) S(5) R(3) R(2) R(0) R(3) R(1)
IRRI101  Philippines R(1) S(5) S(7) R(1) R(2) R(0) R(1)
KI-1117  South Korea R(1) R(2) S(7) R(0) R(1) R(1) R(1)
Y34  China R(0) R(2) R(2) R(0) R(1) R(1) R(1)
F1001-7-2-1  China R(1) S(7) R(3) R(2) R(1) R(1) R(1)
R: ; S: ; ( ):  ; (9,21,23): Pi9(t) + Xa21 + Xa23!
R: resistance, S: susceptible, ( ): resistance level; (9,21,23): Pi9(t) + Xa21 + Xa23.

3! L17~L20#$% 
Fig. 3 Resistance of parents and pyramided lines to BB at seedling stage

4& L17~L20#$% 
Fig. 4 Resistance of parents and pyramided lines to BB at heading stage
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References
[1] Xiong Z-M($%&), Cai H-F((), Min S-K()*+).
Rice in China (,-). Beijing: Chinese Agricultural Sci-
entech Press, 1992. pp 118−121 (in Chinese)
[2] Zhai W-X(./0), Zhu L-H(123). Rice bacterial blight
resistance genes and their utilization in molecular breeding.
Prog Biotechnol (456789), 1999, 19(6): 9−15 (in Chi-
nese with English abstract)
[3] Zhang Q(:;). Highlights in identification and application of
resistance genes to bacterial blight. Chin J Rice Sci (,-<
0), 2005, 19(5): 453−459 (in Chinese with English abstract)
[4] Khush G S, Bacalangco E, Ogawa T. A new gene for resis-
tance to bacterial blight from O. longistaminata. Rice Genet
Newsl, 1990, 7: 121−122
[5] Zhang Q(:;), Zhao B-Y(=>?), Wang C-L(@AB), Lin
S-C(CDE), Que G-S(FG4), Yang W-C(H/I), Xing
Q-D(JKL), Zhou Y-L(MNO), Li D-Y(PQR), Chen
C-B(SET), Zhu L-H(123). Identifying and tag a new
gene for resistance to bacterial blight (Xanthomonas oryzae
pv. oryzae) from O. rufipogon. Sci Agric Sin (UV<0),
1999, 32(3): 109 (in Chicese with English abstract)
[6] Song W Y, Wang G L, Chen L L, Kim H S, Pi L Y, Holsten T,
Gandner J, Wang B, Zhai W X, Zhu L H, Fauquet C, Ronald P.
A receptor kinase-like protein encoded. Science, 1995, 270:
1804−1806
[7] Zhang Q(:;), Zhao B-Y(=>?), Zhao K-J(=WX), Wang
C-L(@AB), Yang W-C(H/I), Lin S-C(CDE), Que
G-S(FG4), Zhou Y-L(MNO), Li D-Y(PQR), Chen
C-B(SET), Zhu L-H(123). Identifying and mapping a
new gene Xa-23(t) for resistance to bacterial blight (Xantho-
monas oryzae pv. oryzae) from O. rufipogon. Acta Agron Sin
(Y50Z), 2000, 26(5): 536−542 (in Chinese with English
abstract)
[8] Pan H-J([\X), Wang C-L(@AB), Zhao K-J(=WX),
Zhang Q(:;), Fan Y-L(]^_), Zhou S-C(M`a), Zhu
L-H(123). Molecular mapping by PCR-based markers and
marker-assisted selection of Xa23, a bacterial blight resistance
gene in rice. Acta Agron Sin (Y50Z ), 2003, 29(4):
501−507 (in Chicese with English abstract)
[9] Chen X-J(SbX). Genetic Diversity of Rice Varieties Resis-
trant to Rice Blast and Molecular marker of the Resistance
Genes. MS Dissertation of Yangzhou University, 2003. pp 7−8
(in Chicese with English abstract)
[10] Zheng Y(cd). Screening and Application of an SSR Marker
Closely Linked to Pi-2(t), a Gene Resistant to Rice Blast. MS
Dissertation of. Fujian Agricultural & Forestry University,
 1 :    105


2004. pp 17−18 (in Chinese with English abstract)
[11] Deng Y-W(ef/ ). Genetic analysis and mapping of a
broad-spectrum resistancegene to rice blast (Magnaporthe
grisea). MS Dissertation of Chinese Academy of Agricultural
Sciences, 2004. pp 9−11 (in Chicese with English abstract)
[12] Liu G, Lu G, Zeng L, Wang G L. Two broad-spectrum blast resis-
tance genes, Pi9(t) and Pi2(t), are physically linked on rice
chromosome 6. Mol Genet Genomics, 2002, 267: 472−480
[13] Qu S H, Liu G F, Zhou B, Bellizzi M, Zeng L R, Dai L Y, Han
B, Wang G L. The broad-spectrum blast resistance gene Pi9
encodes an NBS-LRR protein and is a member of a multigene
family in rice. Genetices, 2006, 172: 1901−1914
[14] Huang S-W(gD/). Advances in Xanthomonas campestris
pv. oryzae in China. Plant Prot (h5ij), 1994, (1): 29−31
(in Chinese)
[15] China Bureau of Quality and Technical Supervision (kl
mnop). Rules for Investigation and Forecast of Main Crop
Diseases and Insect Pests (Part 1) [qrUY5stZuv
wx (f )]. Beijing: Standards Press of China, 1996. pp
197−215 (in Chinese)
[16] Lu Y-J(yz{), Zheng K-L(c|}). A simple method for
isolation of rice DNA. Chin J Rice Sci (,-<0), 1992,
6(1): 47−48 (in Chinese with English abstract)
[17] Wang G L, Song W Y, Ruan D L, Sideris S, Ronald P C. The
cloned gene, Xa21, confers resistance to multiple Xanthomo-
nas oryzae pv. isolates in transgenic plants. Mol Plant-Mirobe
Int, 1996, 9: 850−855
[18] Ni D-H(~€), Yi C-X(E‚), Li L (Pƒ), Wang X-F(„
…†), Wang W-X(@/‡), Yang J-B(Hˆ‰). Pyramiding
Xa21 and Pi9(t) in rice by marker-assisted selection. Mol
Plant Breed(h5Š), 2005, 3(3): 329−334 (in Chicese
with English abstract)




















[19] Zheng K-L(c|}), Zhuang J-Y(‹Œ), Wang H-R(@Ž
). Performance of resistance gene pyramids to races of rice
bacterial blight in Zhejiang province. Hereditas (‘), 1998,
20(4): 4−6 (in Chicese with English abstract)
[20] Xu J-L(’“”), Lin Y-Z(C•–), Weng J-P(—˜™), Zhao
L-X(=2‚). Convergence of resistance genes to bacterial
blight in rice and its genetic effect. Acta Agron Sin (Y50
Z), 1996, 22(2): 129−134 (in Chicese with English abstract)
[21] Sanchez A C, Brar D S, Huang N, Li Z K, Khush G S. Sequence
tagged site marker-assisted selection for three bacterial blight re-
sistance genes in rice. Crop Sci, 2000, 40: 792−797
[22] Yoshimura S, Yoshimura A, Iwata N, McCouch S R. Tagging
and combining bacterial blight resistance gene in rice using
RAPD and RFLP markers. Mol Breed, 1995, 1: 375−387
[23] Huang N, Angeles E R, Domingo J, Magpantay G, Singh S,
Zhang G, Kumaravadivel N, Bennett J, Khush G S. Pyramid-
ing of bacterial blight resistance genes in rice:
marker-assisted selection using RFLP and PCR. Theor Appl
Genet, 1997, 95: 313−320
[24] Deng Q-M(eš›), Zhou Y-J(M?œ), Jiang Z-X(žŸ),
Wan Y-X( ¡…), Zhao B(=T), Yang L(Hƒ), Li P(P¢).
Pyramiding bacterial blight (BB) resistance genes (Xa21, Xa4
and Xa23) into rice and its effect analysis. Acta Agron Sin (Y
50Z), 2005, 31(9): 1241−1246
[25] Domingo J P, New T W, Kumaravaclivel N G, Magpantay G B,
Hittalmani S, Parco A S, Huang N, Angeles E R, Khush G S. Rice
resistant breeding to bacterial blight and blast by Molecular
Marker-assisted Selection. Philippine J Crop Sci, 1995, 20: 3
[26] Narayanar N N, Baisakh N, Vera Cruz C M, Gnanamanickam
S S, Datta K, Datta S K. Improvement rice resistance to bac-
terial blight and blast through molecular breeding. Crop Sci,
2002, 42: 2072−2079