全 文 ：Vol. 30 , No. 9
pp. 872 - 877 　Sept. , 2004
作 　物 　学 　报
ACTA AGRONOMICA SINICA
第 30 卷 第 9 期
2004 年 9 月 　872～877 页
Inheritance of Resistance in Rice Cultivars of USA to Pyricularia grisea Races IE2
1k , IB233 , IB249 , and IC217
YAN Zong2Bu
( Rice Research Institute , Guizhou Academy of Agricultural Sciences , Guiyang 550006 , Guizhou , China)
Abstract 　A complete set of diallel crosses were made among 5 USA rice cultivars of RA73 , Katy , Lemont , L202 and
Bond to identify the inheritance of rice blast ( Pyricularia grisea) resistance to the races of IE21k , I233 , IB249 and IC2171
Parents , F1 , F2 and some random selected F22derived lines from the F3 were tested in the greenhouse at Stuttgart , Arkansas
of USA during October 1994 to May 19951 The results showed that all parents were susceptible to race IB233 , all parents
except RA73 were susceptible to race IE21k , and all parents except Katy were susceptible to races IB249 and IC2171 The
inheritance of resistance to race IE21k was controlled by two dominate complementary genes in the crosses involving parent
RA73 , to race IB233 by two non2allelic susceptible genes in the cross between Lemont and L202 , showing two dominant
complementary resistance genes in their original wild2types and their progenies of the cross ; there were two independent and
dominant resistance gene loci to IB249 or IC217 in the crosses involving resistant parent Katy except one single resistant and
dominant gene locus inheritance in the crosses RA73/ Katy and Katy/ RA73 to IB249 ; and the F2 progenies were all suscep2
tible to race IE21k from the crosses among susceptible parents of Lemont , L202 , Katy and Bond ; to race IB233 from the
crosses among susceptible parents of RA73 , Katy and Bond , and to races IB249 and IC217 from the crosses among suscepti2
ble parents of RA73 , Lemont , L202 and Bond , indicating the absence of complementary resistance genes in these parents
to corresponding 4 races and probable allele of the susceptible genes in these parents1
Key words 　Rice ( Oryza sativa L1) ; Pyricularia grisea Race ;Resistance ; Inheritance
美国水稻品种对稻瘟病小种 IE21k、IB233、IB249 和 IC217 的抗性遗传
严宗卜
(贵州省农业科学院水稻研究所 ,贵州贵阳 550006)
摘 　要 　1994 年 10 月至 1995 年 5 月 ,在美国阿肯色大学水稻研究推广中心的温室 ,对 5 个美国水稻品种 Katy、Lemont、
L202、RA73 和Bond ,及其 F1 、F2 和部分组合的 F3 随机选系 ,用 4 个主要美国稻瘟病菌小种 IE21k、IB233、IB249 和 IC217 进行
接种鉴定 ,通过完全双列杂交进行遗传分析的研究。结果表明 :所有的亲本对 IB233 感病 ;除 RA73 外 ,其他亲本对 IE21k
感病 ;除 Katy外 ,其他亲本对 IB249 和 IC217 感病。对稻瘟病菌小种 IE21k ,抗病亲本 RA73 与其他感病亲本组配的组合的
F1 表现抗病 ,F2 呈 9R∶7S的比例 ,表明 RA73 的抗性由 2 对显性互补基因控制。对病菌小种 IB233 ,感病亲本 Lemont 与同
样感病的亲本L202 的 F1 表现抗病 ,F2 呈 9R∶7S的抗、感比例 ,表明这 2 个亲本感病基因不等位 ,它们的原始品种和部分
后代中存在 2 对显性互补抗病基因 ,各有 1 对抗性基因分别位于感病亲本 Lemont 和 L202 中 ,这 2 个显性互补抗病基因
同时存在时 ,才表现出抗病性。对病菌小种 IB249 和 IC217 ,除抗病品种 Katy与 RA73 组配的组合 F2 对 IB249 呈 3R∶1S 的
抗、感比例 ,表现为 1 对显性基因遗传外 ,抗病品种 Katy与其他亲本杂交 , F2 呈 15R∶1S的抗、感比例 ,表现为 2 对独立的
显性抗病基因遗传。感病亲本 Lemont、L202、Katy和 Bond 对小种 IE21k ,感病亲本 RA73、Katy和 Bond 对小种 IB233 ,以及感
病亲本 RA73、Lemont、L202 和 Bond 对小种 IB249 和 IC217 ,其 F2 的植株全为感病 ,说明这些亲本对相应的小种缺乏互补的
抗病基因 ,其感病基因是等位的。
关键词 　水稻 ;稻瘟病菌小种 ;抗性 ;遗传
中图分类号 : S51111 ; S4351111141
Foundation item :Research was supported by the China Foundation for International Personnel Exchange and the Arkansas State (USA) Foundation for
Rice Research and Promotion1
Biography :YAN Zong2Bu(1948 - ) , Male , Associate Professor , Born in Jinhua County of Zhejiang Province , P1 R1 China1 Tel : (0851) 3762727
Received(收稿日期) :2003212224 , Accepted (接受日期) :20042042011

　　Rice blast disease caused by Pyricularia grisea is
the most devastating rice disease1 Resistance of rice to
rice blast is generally governed by few major genes and
resistant cultivars are recognized as the most economical
way to control rice blast1 Some resistant cultivars have
been released in past years1 However , the blast pathogen
is highly variable in rice production and new blast patho2
types have evolved , while other pathotypes have shifted
from minor to major importance1 Races IB249 and IC217
are major pathotypes in the southern USA1 Katy , Kaybon2
net and some other cultivars could control these two blast
races1 Blast race IE21k which was derived from an isolate
collected on Katy , has caused susceptibility on Katy and
Kaybonnet , and a new race IB233 may also become into
major pathotype1 The knowledge of the inheritance of re2
sistance and finding new resistant sources to rice blast
races IE21k , IB233 , IB249 and IC217 will be beneficial
to rice researchers in the breeding and pathology[1 ]1
1 　Materials and Methods
Five parents RA73(Bonnet 73 treated with fast2neu2
trons at rate of 1 800 Rads in Oak Ridge , Tennessee of
USA) , Lemont , L202 , Katy and Bond were selected and
a complete set of diallel crosses were made1 The parents
(P) , F1 , F2 , some F3 and two susceptible checks
(M201 , NP125) were tested with four rice blast pathogen
races in the plastic flats (each 54 by 38 by 10 cm) under
the high N fertility and drought stress to induce the sus2
ceptible plants to severe symptom of rice blast1 The re2
search was conducted in the greenhouse at the Stuttgart ,
Arkansas of USA from October 1994 to May 19951
Seedling was inoculated at the four2leaf stage by
spraying with 16 ×104 to 22 ×104 spores·mL - 11 The
inoculated plants were kept in the moist chambers with
over 90 % humidity at about 25 ℃ for a day and then
moved to the greenhouse at 28 to 35 ℃1 Disease reactions
were read 6 to 8 days after inoculation , when typical le2
sions appeared on the leaves of susceptible checks[2 ]1
The Arkansas RREC Blast Leaf Rating Scale System
(0 to 9 scale) was used to evaluate the lesion develop2
ment and determine resistance or susceptibility1 On this
scale , 0 = no symptoms evident to indicate the plant was
challenged ; 1 = small pin point flecks ; 2 = larger in2
fection sites indicating infection had begun but develop2
ment was quickly limited by plant response ; 3 = lesions
larger than 2 but with the lesion center still closed and of2
ten starting to elongate , sometimes as much as 3 - 4 mm ;
4 = elongated to or had opened slightly and the phy2
toalexin response very evident ; 5 = usually elongated and
spindle shaped with a well opened center , and develop2
ment between veins was inhibited and there was definite
discoloration indicating phytoalexin response ; 6 = still
tended to be spindle shaped but with less indication of
lateral inhibition and with much less indication of discolo2
ration at the border1 7 = a definite susceptible reaction
with very little indication of discoloration near the lesion
of border ; 8 = between 7 and 9 , but the plant was not
dead ; 9 = leaves were usually dead by the time the other
plots were ready for evaluation 7 - 9 days , and plants
were hypersensitive with little1 The reactions of the two
parents in each plate were also considered when the pro2
genies were evaluated1
The ratings of 0 - 4 were considered to be resistant
and 5 - 9 to be susceptible1 The chi2square test for good2
ness of fit to expected ratios was applied to the observed
ratios for the F2 and F3 generations[3 ]1
2 　Results
Tentative tests showed the following results1 All pa2
rents and checks were susceptible to all races , except that
RA73 , Katy and check NP125 were resistant reactions to
race IE21k , races IB249 , IC217 and race IB233 , IB249
respectively (Table 1) 1
Table 1 Reaction of parents and checks to rice
blast( Pyricularia grisea) races IE21 K, IB233 ,
IB249 and IC217 at Stuttgart , Arkansas( 1994)
Parent or
check(CK)
Leaf reaction in the greenhouse
IE21k IB233 IB249 IC217
RA73 R(211) S(517) S(612) S(516)
Lemont S(518) S(512) S(516) S(514)
L202 S(511) S(513) S(519) S(518)
Katy S(612) S(617) R(014) R(018)
Bond S(710) S(711) S(619) S (618)
M201(CK1) S(711) S(712) S(617) S(619)
NP125 (CK2) S(518) R(216) R(213) S(614)
　　Notes : 3 R = Resistant (1 - 4 scale) ; S = Susceptible (5 - 9 scale) 13 3 Race designation according to the Arkansas RREC Blast Leaf Rating Scale
System1
　　The reactions of the F1 hybrids from crosses among
susceptible parents to IB233 , except for Lemont/ L202 and
L202/ Lemont , were susceptible and from those crosses a2
mong resistant parents / susceptible parents were resistant
378　9 期 YAN Zong2Bu : Inheritance of Resistance in Rice Cultivars of USA to Pyricularia grisea Races IE21k ,. . . 　　　

(Table 2) 1
There were 4 types of segregations of resistance and
susceptibility in the 20 F2 progenies derived from a com2
plete diallel among 5 parents ( Tables 3 , 4 , 6 ,7) : (1)
Two genes were involved independently and dominantly in
the inheritance of blast resistance1 Plants were resistant
when any dominant allele or more from the 2 independent
genes was at present1 Plants were susceptible when the 2
independent genes were homogeneously recessive1 Then ,
F2 population segregated in accordance with 15 resistant∶1
susceptible ; (2) however , when two genes worked domi2
nantly and complementarily to result in the resistant , the
segregation of F2 progeny became 9 resistance∶7 suscepti2
ble ; (3) single dominantly gene ruled the resistance , and
F2 population showed 3 resistant∶1 susceptible segrega2
tion ; and (4) plants in F2 population were uniformly sus2
ceptible when the F2 progeny was derived from 2 suscepti2
ble parents except for Lemont/ L202 to race IB2331
The segregation ratios of the F2 progenies were 9R∶
7S to race IE21k in the crosses between resistant parent
RA73 and the susceptible parents Lemont , L202 , Katy
and Bond (including their reciprocals) 1 It indicated that
inheritance to race IE21k was controlled by two dominant
complementary genes in RA73 (Table 3) 1
Table 2 Disease reaction of F1 generations from 5 rice parental combinations to 4 blast ( Pyricularia grisea)
races in the greenhouse at Stuttgart , Arkansas , USA( 1994 - 1995)
Cross IE21k IB233 IB249 IC217
P F1 P F1 P F1 P F1
1 RA73/ Lemont R/ S R(215) S/ S S(516) S/ S S(611) S/ S S(516)
2 Lemont/ RA73 S/ R R(214) S/ S S(519) S/ S S(517) S/ S S(511)
3 RA73/ Katy R/ S R(210) S/ S S(510) S/ R R(111) S/ R R(113)
4 Katy/ RA73 S/ R R(117) S/ S S(610) R/ S R(019) R/ S R(113)
5 RA73/ Bond R/ S R(216) S/ S S(517) S/ S S(619) S/ S S(517)
6 Bond/ RA73 S/ R R(217) S/ S S(619) S/ S S(716) S/ S S(517)
7 RA73/ L202 R/ S R(313) S/ S S(611) S/ S S(614) S/ S S(515)
8 L202/ RA73 S/ R R(216) S/ S S(612) S/ S S(617) S/ S S (512)
9 Katy/ Lemont S/ S S(618) S/ S S(514) R/ S R(018) R/ S R(113)
10 Lemont/ Katy S/ S S(616) S/ S S(513) S/ R R(016) S/ R R(110)
11 Katy/ L202 S/ S S(616) S/ S S(512) R/ S R(019) R/ S R(111)
12 L202/ Katy S/ S S(516) S/ S S(517) S/ R R(110) S/ R R(113)
13 Katy/ Bond S/ S S(610) S/ S S(510) R/ S R(016) R/ S R(019)
14 Bond/ Katy S/ S S(619) S/ S S(510) S/ R R(016) S/ R R(112)
15 Lemont/ L202 S/ S S(617) S/ S R(318) S/ S S(516) S/ S S(513)
16 L202/ Lemont S/ S S(612) S/ S R(410) S/ S S(513) S/ S S(511)
17 L202/ Bond S/ S S(616) S/ S S(512) S/ S S(617) S/ S S(616)
18 Bond/ L202 S/ S S(711) S/ S S(519) S/ S S(619) S/ S S(619)
19 Lemont/ Bond S/ S S(519) S/ S S(510) S/ S S(519) S/ S S(610)
20 Bond/ Lemont S/ S S(618) S/ S S(519) S/ S S(518) S/ S S(613)
　　Notes : R : 1 - 4 scale ; S : 5 - 6 scale1 The numbers in the parentheses are disease scales1
Table 3 Segregation ratios of resistant( R)∶susceptible( S) in F2 progenies of rice crosses and reciprocals among five parents to race IE21k
Parent RA73R
Lemont
S
L202
S
Katy
S
Bond
S
RA73 R 9∶7 3 9∶7 9∶7 9∶7
131∶112 3 3 75∶56 151∶104 75∶56
χ2 = 0154 χ2 = 0142 χ2 = 0192 χ2 = 0152
P = 015 - 0125 P = 0175 - 015 P = 015 - 0125 P = 015 - 0125
Lemont 9∶7 S 0∶1 0∶1 0∶1
113∶80 0∶161 0∶172 0∶125
χ2 = 0141
P = 0175 - 015
L202 9∶7 0∶1 S 0∶1 0∶1
89∶81 0∶125 0∶124 0∶127
χ2 = 1104
P = 015 - 0125
Katy 9∶7 0∶1 0∶1 S 0∶1
101∶86 0∶132 0∶123 0∶119
χ2 = 0138
P = 0175 - 0150
Bond 9∶7 0∶1 0∶1 0∶1 S
107∶88 0∶171 0∶158 0∶182
χ2 = 0115
P = 0175 - 0150
　　Notes : 3 Expected ratio R∶S; 3 3 Observed ratio R∶S1
478 　　　作 　　物 　　学 　　报 30 卷 　

　　The segregation ratio of the F2 progeny was 9R∶7S to
race IB233 in the crosses between two susceptible parents
Lemont and L202 , although their F1 hybrid was moderate2
ly resistant to IB233 , showing the two susceptible parents
had two non2allelic complementary genes ( Table 4) 1 It
implied that these two parents might have two resistant
genes background in their original wild2types and each
parent just had one dominant resistant complementary
gene showing susceptible phenotype1
The F3 progenies from the cross Lemont/ L202 and its
reciprocal L202/ Lemont fited the ratio of 1R∶8Sg∶7S , in
which two complementary genes controled the inheritance
(Table 5) 1
Two types of F2 progeny distributions occurred in the
resistant ×susceptible crosses to races IB2491 For exam2
ple , in the crosses of Katy/ RA73 and RA73/ Katy , IB249
the segregation ratios were 3R∶1S , indicating that the re2
sistance was dominant and controlled completely by one
single major gene ; in F2 populations from the crosses of
Katy with the other parents , the ratios were 15R∶1S1
There were possibly two dominant and independent genes
in Katy controlling resistance (Table 6) 1
Table 4 Segregation ratios of resistant( R)∶susceptible( S) in F2 progenies of rice crosses and reciprocals among five parents to race IB233
Parent RA73S
Lemont
S
L202
S
Katy
S
Bond
S
RA73 S 0∶1 3 0∶1 0∶1 0∶1
0∶146 3 3 0∶135 0∶145 0∶139
Lemont 0∶1 S 9∶7 0∶1 0∶1
0∶126 79∶75 0∶132 0∶172
χ2 = 0153
P = 015 - 0125
L202 0∶1 9∶7 S 0∶1 0∶1
0∶155 86∶75 0∶131 0∶128
χ2 = 1153
P = 0125 - 011
Katy 0∶1 0∶1 0∶1 S 0∶1
0∶123 0∶119 0∶127 0∶126
Bond 0∶1 0∶1 0∶1 0∶1 S
0∶119 0∶223 0∶195 0∶124
　　Notes : 3 Expected ratio R∶S; 3 3 Observed ratio R∶S1
Table 5 Reaction No1 of F32lines for rice blast race IB233
Cross R Sg1 S Total Expected ratio χ2 P
Lemont/ L202 7 72 60 137 1∶8∶7 0148 0190 - 0175
L202/ Lemont 5 69 62 136 1∶8∶7 1156 0150 - 0175
　　Notes : 3 R = Resistant , Sg = Segregating , and S = Susceptible1
Table 6 Segregation ratios of resistant( R)∶susceptible( S) in F2 progenies of rice crosses and reciprocals among five parents to race IB249
Parent RA73S
Lemont
S
L202
S
Katy
R
Bond
S
RA73 S 0∶1 3 0∶1 3∶1 0∶1
0∶148 3 3 0∶173 109∶32 0∶121
χ2 = 0141
P = 0175 - 0150
Lemont 0∶1 S 0∶1 15∶1 0∶1
0∶139 0∶128 122∶12 5∶238
χ2 = 1165
P = 0125 - 011
L202 0∶1 0∶1 S 15∶1 0∶1
0∶173 0∶155 132∶7 0∶231
χ2 = 01354
P = 0175 - 015
Katy 3∶1 15∶1 15∶1 R 15∶1
115∶30 134∶11 127∶10 139∶12
χ2 = 1146 χ2 = 01423 χ2 = 01243 χ2 = 01767
P = 0125 - 011 P = 0175 - 015 P = 0175 - 015 P = 015 - 0125
Bond 0∶1 0∶1 0∶1 15∶1 S
0∶146 0∶211 0∶233 116∶13
χ2 = 3116
P = 011 - 0105
　　Notes : 3 Expected ratio R∶S; 3 3 Observed ratio R∶S1
578　9 期 YAN Zong2Bu : Inheritance of Resistance in Rice Cultivars of USA to Pyricularia grisea Races IE21k ,. . . 　　　

　　One type of F2 progeny distribution occurred in the
crosses of resistant parent Katy with the other 4 suscepti2
ble parents RA73 , Lemont , L202 and Bond to race IC2 17 , i1e1 with a segregation ratio 15R∶1S , indicating thatthere were two independent and dominant genes in Katy torace IC217 (Table 7) 1
Table 7 Segregation ratios of resistant( R)∶susceptible( S) in population F2
progenies of rice crosses and reciprocals among five parents to race IC217
Parent RA73S
Lemont
S
L202
S
Katy
R
Bond
S
RA73 S 0∶1 3 0∶1 15∶1 0∶1
0∶136 3 0∶175 241∶23 0∶195
χ2 = 2173
P = 011 - 0105
Lemont 0∶1 S 0∶1 15∶1 0∶1
0∶124 0∶128 124∶8 0∶211
χ2 = 01012
P = 0195 - 019
L202 0∶1 0∶1 S 15∶1 0∶1
0∶164 0∶129 206∶19 0∶231
χ2 = 1182
P = 0125 - 011
Katy 15∶1 15∶1 15∶1 R 15∶1
309∶22 117∶8 123∶10 119∶9
χ2 = 01087 χ2 = 01006 χ2 = 0137 χ2 = 0113
P = 0190 - 0175 P = 0195 - 019 P = 0175 - 015 P = 0175 - 015
Bond 0∶1 0∶1 0∶1 15∶1 S
0∶198 0∶238 0∶233 131∶14
χ2 = 2182
P = 011 - 0105
　　Notes : 3 Expected ratio R∶S; 3 3 Observed ratio R∶S1
3 　Discussion
It has been known that there are 6 resistance genes
Pi2i , Pi2d , Pi2kh , Pi2ks , Pi2ta2 and Pi2z in the rice
cultivars of USA[4 ]1 Katy has the Pi2ta2 gene or both the
Pi2a and Pi2ta2 genes[1 ]1 It was unclear what resistance
gene (s) to IE21k existed in RA73 , and what complemen2
tary resistance gene (s) to IB233 in Lemont or L2021 This
research showed NP125 is a resistant cultivar to race IB2
33 and IB249 and could be used to improve rice resistance
in breeding program1 Unfortunately , its has quality makes
the process of breeding complicated1 Lemont and L202
are popular cultivars in the production of USA1 It would
be easier to use their resistance genes to IB233 in rice re2
sistance breeding program1
The segregation ratios of the F2 progenies were 9R∶
7S to race IB233 in the crosses between two susceptible
parents Lemont and L2021 Their F1 hybrids were moder2
ately resistant to IB2331 It showed that these two suscepti2
ble parents had two non2allelic complementary genes
(Table 4) 1 Lemont or L202 might have one resistance
gene to IB233 , respectively , implying that the susceptible rice cultivars contained resistant genes1 Two different sus2ceptible genes to race IB233 were probably on the differentchromosome of rice1 It could be supposed that a originalrice wild2type had two resistance genes LL MM to IB233 ,Lemont just had MM nn genes and the nn genes re2pressed MM genes , and the phenotype was susceptible ,L202 had mm NN genes and the mm genes repressed NNgenes , and the phenotype was susceptible1 When Lemontcrossed with L202 , F1 ( Mm Nn) showed resistant , andF2 might be segregated as the resistant wild2types( M2N2)and the susceptible new types ( mm nn) besides the typesof susceptible parents( M2 nn , mm N2) 1 The segregationratios could be 9R∶7S in F2 generations and genetic modeshould follow the postulate in Figure 11RA73 also could have two complementary resistancegenes to IE21k and it could complement resistance weakto IE21k in Katy , Lemont , L202 and Bond1 Also thereare resistance genes in Katy to races IB49 and IC17 , re2spectively1 The resistance genes which were more thanone locus could be used to rice breeding to reduce the riskbeing inherent in a single , vulnerable genetic back2ground1
678 　　　作 　　物 　　学 　　报 30 卷 　

Fig11 The segregation ratio , genetic mode , phenotype and
resistance to race IB233 of the cross between Lemont and L202
　　To race IB249 : Parent Katy might have two resis2
tance genes KK TT and its phenotype be resistant1 Parent
L202 , Lemont or Bond might have kk tt genes and its
phenotype be susceptible1 The segregation ratios could be
15R∶1S in F2 generations of Katy/ L202 , Katy/ Lemont ,
Katy/ Bond and their reciprocals1 But parent RA73 might
have kk RR genes and the kk genes could repress RR
genes and its phenotype be susceptible1 The segregation
ratios could be 3R∶1S in F2 generations of Katy/ RA73
and RA73/ Katy1 Acknowledgment 　I wish to thank the China Asso2ciation for International Personnel , the Guizhou Academyof Agricultural Sciences in P1 R1 China , the ArkansasRice Research and Promotion Board , the Rice Research& Extension Center (RREC) of University of Arkansas inthe United States of America for financial support1 I alsowish to thank Drs K1 A1 K1 Moldenhauer and F1N1 Lee ,Professors of the RREC in the University of Arkansas fortheir technical guidance1References[1 ] 　Marchetti M A , Lai Xinghua , Bollich C N1 Inheritance of resistance toPyricularia oryzae in rice cultivars grown in the United States1 Phy2topathology , 1987 , 77 :799 - 804[2 ] 　Moldenhauer KA K, Bastawisi A O , Lee F N1 Inheritance of resistancein rice to races IB249 and IC217 of Pyricularia grisea rice blast1 CropScience , 1992 , 32 :584 - 588[3 ] 　Ling K C , Ou S H1 Standardization of the international race numbers ofPyricularia oryzae1 Phytopathology , 1969 , 59 :339 - 342[4 ] 　Marchetti M A1 Race2specific and rate2reducing resistance to rice blastin US rice cultivars1 In : Rice Blast Disease1 IRRI , PO Box 933 ,Manila , The Philippines , 19941231 - 244
778　9 期 YAN Zong2Bu : Inheritance of Resistance in Rice Cultivars of USA to Pyricularia grisea Races IE21k ,. . .