JARQ 27, 71-80 (1993)

Methods and Strategy for Monitoring Race Distribution and Identification of Resistance Genes to Bacterial Leaf Blight (Xanthomonas campestris pv. oryzae) in Rice

Tsugufumi OGAWA Department of Lowland Fanning, Kyushu National Agricultural Experiment Station (Chikugo, Fukuoka, 833 Japan)

Abstract

For controlling bacterial leaf blight of rice, caused by Xanthomonas campestris pv. oryzae, the use of resistant cul ti vars is the most economical and effective method due to the scarcity of effective bactericidal agents and to the need for preserving the environment. Against this background, the resistance genes to this disease so far identified will be reviewed. Under the collaboration between the Tropical Agriculture Research Center, Japan and the International Rice Research Institute, Philippines, the genes identified were rearranged from Xa-1 to Xa-12 based on the numbering system of rice gene symbols and them near-isogenic lines with single resistance genes were developed. By using these near-isogenic lines, the strategy for monitor­ing the race distribution and the methods of identification of new resistance genes are reviewed.

Discipline: Pl an breeding Additional keywords: allelism test, differentials, near-isogenic line, plant disease

In troduct ion

Bacterial leaf blight caused by Xa111ho111onas ca111pes1ris pv. o,ywe is responsible for heavy clama.gc to rice in the rice-growing countries. For control ­ling the disease, the use of resistant cuhivars is the most economical and effective method clue 10 the scarcit)' of effect ive bactericidal agen ts and 10 the need for preserving the envi ronment.

Since the pathogenic specialization of the causal bacterium of rice bacterial leaf blight was fi rst rcpon­ecl in Japan, a number of reports have been pub­lished on the variabili ty of the pathogenicity of the bacterium and of the resistance of rice cuhivars.

Since the rice cult ivars and bacterial races used as differen tia ls in each country were different, the respect ive groups of scientists found it difficult 10 dist inguish the resistance gene(s). In order 10 con­tro l the disease, it was deemed important 10 set up a common base 10 define the relat ionship betwe,en the viru lence of the bacteri al races and the resistance of rice cuhivars 10 the races. Recent research on

bacterial leaf blight has been carried out mostly in Japan and at lRRI (Internat ional Rice Research Institu te, Philippines) and in both locations differ­ent differential cultivars and bacterial groups were used.

Against this background, the collaborative studies on the resistance to rice bacteria l leaf blight between Japan and I RR l were carried out fo r establ ishing a common base of research and for con1rolling the clisease.

This paper deals wi th the resu lts of the collabora­tion and the strategy for monitoring the race distri­but ion and for the ident ificat ion of resistance genes using the near-isogenic lines developed under the col­laboration.

Resistance genes to bacterial leaf blight of rice

/) Genes identified in various co1111tries The ident ificat ion of the resistance genes in each

country, except for Xa-kg, was based on analyses using local bacterial isolates. As a result of the genet­ic studies on the resistance 10 the disease conducted

72 JARQ 27(2) 1993

Gene ide111ified

x. X1, X.1

Xa-1

Xa- 2

X<1-3

Xa- 11'

XC1-kg 11

)(11-1/

Tublc I. Resistance genes 10 bacterial lcnf blight ori11inally identified in rice ui

Cuhivar analyzed

Kog)•oku Shi11101suki

Kogyoku Koganemaru Pi No. I Ra111ai Emas 2

Wasc Aikoku 3 Java 14 Koentoclan Nagomasari

IR28 IR29 IR30 IR28 IR29 IR30 IR944-102-2- 3-RP9-3

Isolate used

J a11anese isolates

Gikcn 44 Nara Himeji X - 17

X -17 X- 14 Q6808 (I) Q7102 (I) T 7174 (I) H5809 (1 1) T7147 (II) Q6809 (Ill ) T7133 (I ll) T7174 (I)

H75304 (V)

T7174 (I) T7147 (Ill T713J (I IIA) IVA7505 (IV)

Note

Compleme111ary gene for X,

Chromosome 11 (Nishimura 1961)

Linked with Xa- 1 (2-160/o)

Adu l1 resistance

Linked with X11- J h :

(2.0±0.65%)

Rerercncc

30) 30)

22}

22)

I)

32)

32)

9)

..... --·-. ··-. -~. -. __. .............................. ·-.. ·-. ----. -------- .. ---·· ..................... - -.. --.. ---.... --.. ~-- ............. ····· .... ---.............. ..

X11-4

.m-5

Xa- 4•

Xu- 7

xo-8 .w,-9

X11-IO

IR20 IR22 IR1 529-680- 3 IR1545- 339 RP291 - 7 IR.22 Sigadis TKM6, CIC.

Sernora Mangga Malagki1 Sungsong Zenith , ere. DZ78 DV85 OV86 Pl23 I 129 Khao Lay Nhay Satcng Cas209

Philippine isolates

PXO 25 (I)

PXO 25 (I)

PXO 61 ( I )

rxo 61 (IJ PXO 61 (I)

PXO 61 (1)

PXO 61 (I) PXO 61 (I)

PXO 61 ( I ) PXO 86 (2) PXO 79 (3) PXO 71 (4)

Adull rcsisrance

Ad ull resistance

Linked with Xo- 6 (5.9%)

Linked with X11- 4 (27 .6 ± 0.2)

Chromosome 5 (Shamy er al. 1960}

21)

21)

4)

4)

23)

24)

24} 26)

34)

--·--. . .. ..... u ••••••• • • •• ••• •• _. ... . ......... . ... ... - • •••• .• ••••••• ___,. .... ... .. · -· ••••• --• - --·- ••• -- · - ·· . · ·-· ........ . · · ·-- -- • • --. . .................. . . .

73

(Table I, ,ontinued)

GeM Cul1ivar analyzed idcn1ificd

[sola1c used Note Reference

Sri L,inlrnn isol:llcs

Xa- a, \Vase Aikoku 3 CAR I Multiple genes 31)

Xfl- k X/1-i Pl209938 Multi1ilc i:cncs 31)

Zenilh RL Go1>hcr

Xa- JJ Pl209938 Multiple genes 31)

Zenith Xa-b ll111ebon 11c1/ Rcx;irk lncomple1c 31)

............ ----. - ........................... -..... -. -----·-__ _. ................... -.... ---· ----. ---- .. -- ---· ......... ····----.-- .. -.. --... -.... --.... -... . lndoncsiun isola1cs

Xa-kg Kog)'oku Java 14

Xo-7306 (V)

Linked wi1h Xn-1 (2 0/o)

8)

................... -· .......... ---.. --·. --......................... -. -.. ---. ---- .. --- . -- ---··· . ._ ....... - .. ---- . --- ---- -----------. --... -- ......... -----.----lndi:10 isolalc,

X , OJ I Hl4 2)

Xi H89 XJ H 146 1- X, IRS H 14, 1189, H146 lnhibi1or 10 X,, Xi 2)

and XJ

A MalagkiL, Sungsong XOIO 5)

l1 X032 P, Lacros~c/ Zcnith-Nira I? IRRI 69/ 469

IRR I 70/470

I fl IR8 Inhibitor to P1 ............. --------.............................. ·-.. ·-·---·~---..................... ·--·----. --··- •.... ·-·. ·-· .......... ...................... --·-Chinese isoln1es

IR28 Xa-n Xa-11 Li nkcd wi1h X"-"

(170/o)

36) 35)

mainly in Japan and al IRRI, Xa- 1, Xa-2, and X/1- 3 were iden1ified using Japanese isola tes in Japan"rn, while Xa- kg was identified using an I ndoncsian isolate in JapanK>. Furthermore, two al­leles of Xa-1 and Xa-kg were recognized using Japanese isola1es in Japan and they were designated as Xa-/h and Xa-kgh, respectivelym. On 1he other hand, Xa-4, xa-5, Xa-6, Xa-7, xa-8, xa-9, and Xa-10 were identified using Philippine isolates a1 IRR 11.io.i i •23.iuo.J·•>. Xa- 4 b was recognized as

an allele of Xa-4 4•25

'.

Genetic studies on the resisiance 10 the disease have also been concluc1cd in Sri Lanka, India and China using isolates obtained in the respec1ive countries. Xa-a and Xa-k in Wase Aikoku 3, and Xa-p and Xa- i in Pl209938 were identified using Sri Lankan

isolatesJ 11 • The incompletely dominant gene, Xa-b was also identified in Bluebonnet/ Rexark using Sri Lankan isolates3 1>. The th ree complcrne111ary genes. Xa1 , Xai, and XaJ, and the inhibitor o f Xa1, 1-X,, were detected in JR8 using Indian isolates2>. The rresence of two complementary dominant genes, A and 8, in Malagki1 Sungsong, one dominant gene, R, in IRRl69/ 469 and one dominan, gene, P1 , in Lacrosse/Zenith-Nira, was suggested using 1wo Indian isolaies5'. Furthermore, 1wo dominant genes, Xa-a (differe111 from the Xa-<1 described earlier) and Xa-h, were identified using Chinese st rainsJS,J~>. Genetic studies on 1he resistance of rice cultivars to the disease have also been carried out in Korea, Bangladesh, and Indonesia. However, the genes have no, been designated. The iden1ified resistance genes

74

10 bacterial leaf bligh1 are summarized in Table I.

2) Rearrangement of ide111ified genes The rcsuhs of iclent i fica1ion of resisiance genes to

1he disease obiained from each coumry can not be compared because each researcher used isola1es col­lec1ed in 1he rcspec1ivc countries. However, 1he genes. identified in Japan and a1 IRR! were compared wi1h each other using Japanese and Philippine isola1cs during 1he collabora1ive s1udies. As a result , the rcsis1ance genes, Xa-1, Xa-2, Xa-3, Xa-4, xa-5, Xa-7, xa-8, Xa-/0, and Xa-kg were confirmed to be cl irferem from each 01her13

·"'1• In addition, a new resisiance gene to the Japanese isola1es, Xa-1 /

JARQ 27(2) 1993

was iden ti fied in J RS, 1he susceptible clifferc111ial 10 Philippine isola1es9• 181 • However, Xa-6, xa-9 and Xa-4b iden1ified at IRR! were allelic to Xa-3 iden­tified in Japan•;-171• Based on these results, gene symbols for the resistance genes to bac1erial leaf bligh1 were rearranged fol lowing the numbering sys­tem of the rice gene symbols indicated in Table 210>. Therefore, the Xa-kg symbol was rearranged as Xa- 12101

•

The rearrangement of the genes has crca1cd problems which should be solved in future. It is generally recognized that Xa-1, Xa-2, and Xa-12 are very closely linked. his also possible that Xa-1 . Xa-2 and Xa-12 are al leles at 1he same locus. In

Table 2. Reurrnnged genes for resis1ance 10 bacterial leaf blighl

Rearranged gene

Xa- 1 Xa-J h X11-2 Xa-3

Xa-4

.\'{t- 5

Xa- 7 .wi-8 Xa- 10 Xa-/1 Xa- /2 X"-12 11

Dominance

Dominant Dominant D0minan1 D0minan1

D0rni11an1

Recessive Dominan1 Recessive l)ominant D0mlnan1 Dominanl Domi11an1

Original dcsig11a1io11

Xa-1 Xa- Jh

Xa- 2 X(l-w Xa-if b

X"-6 ,\'11-9 X11-4 Xu-4' .vu-5 Xa-7 xa-8 XCl-/0 Xa-/1 Xa-kg Xa- kgh

Reprcse111ativc culliva,·

Kogyoku IR28, IR29, IR30 Ranrni Emas 2, Te-tep Wasc Aikoku 3 Sc111ora Mangga Zenilh Satcng TKM6, IR20, IR22

DZl92, IR1545-339 OV85 1>1231129 Cas209 RP9-3 . IR8 Kogyoku, Java 14 IR28, IR29. IRJO

Table 3. New genes for resistance 10 bacterial leaf blight reccnlly identified

ldcmificd gene

xa-lJ Xa-14 xa-/S• Xa-16 Xa- 17 Xa-18 :m-19 X(l-20 Xa-21

• Nol approved ye1.

Dominance

Recessive Dominant Recessive D0111inan1 D0111inan1 D0minan1 Re<:cssivc Recessive Dominant

Original donor

Harebarc

IR24 IR 24 0. longis·

w111i11a1a

Reprcscmativc cuhivar

8.11. Chinsurah Boro II Taichung Na1ivc I M41 Tc-1cp Asominori I R24, Mil yang 23. Toyonishiki XM5 XM6 IR- DB 21

75

Table 4. Near-isogcnic lines for resistance to bacterial leaf blighl of rice de,·clo11ed under TARC-IRRI collaboralion 191

R- gene designation Generation Line no. Cross

XII- I (Xll-12) 01

IR-BB I BC.F. IS63(l I R24 • 5/Kogyoku IR- BB IOI BC.F, IS638 Toyonishi ki • 5/Kogyoku IR- BB 201 BC.,F. IS634 Milyang 23*5/Kogyoku

Xt,-2 ( Xtr- l) "l IR-lll3 2 BC.,Fs 8 174 I R24. 5/Te-1ep IR-1313 102 13C.,Fs B205 Toyonishiki • 5/Tc-lep IR-Bll 202 BG.Fs 8221 Milyang 23 • 5/Tc-tcp

Xa-3 IR- BB 3 BC.,Fo IS 22 I R24 • 5/Chugoku 45 IR- 813 103 BC.,F0 IS103 Toyonishiki • 5/Chugoku 45 lR-BB 203 BC,Fo IS 13 Mil yang 23 • 5/Chugoku 45

IR-BB JJ BC,Fo IS 40 IR24•5/Java 14 lR-BB 103J BC,,Fo IS 27 Toyonishiki • 5/ Java 14 IR- 1311 203.1 BC,Fo rs 37 Milyang 23*5/ Java 14

!R- BU 3Z BC..!':• IS 74 l R24 .S/Zcni1h IR- 80 103Z BC,F• IS283 Toyonishiki • 5/Zcniih IR- BLI 203Z BC,F,. IS 68 Mil yang 23 • 5/Zcniih

IR- BB JS BC,F• IS 91 I R24 • S/Sa1cng !R-BB IOJS BC,F• 1$ 79 Toyonishiki • 5/Satcng IR-138 203S BC,F• IS341 Mi lyang 23 • 5/Sateng

Xo-4 IR-BB 4 sc,r:. IS i 10 IR24 • 5/1 R20 IR-BD 104 BC,F., IS 98 Toyonishiki • 5/1 R20 IR- BO 204 Bc.r. IS104 Mil yang 23 • 5/1 R20

xa-5 IR-BB 5 BC,,Fs IS133 I R24 • 5/IR 1545-339 IR- BB 105 BC,F, ISi 18 Toyonishiki • 51i'IR 1545-339 !R-88 205 BC,F; !S299 Milyang 23 • 5/lR1545-339

Xa-7 IR-BB 7 BC,F, !Sl6S l R24 • 5/DV85 !R-BB 107 BC,F, IS499 Toyonishiki • 5/ DV85 IR-88 207 BC,F, 1$491 Milyang 23t 5/DV85

Xlf-8

IR-B8 8 BC.Fs IS513 !R24,5/Pl231!29 !R- BB 108 BC.F, IS831 Toyonishiki, S/Pl23 I I 29 IR-1313 208 BC,F; !S8 18 Milyang 2J.S/Pl23 1129

Xa-10 lR-BB 10 BC,F,. lS154 r R24 • 5/Cas209 IR-BB 110 BC.F; !S 140 Toyonishiki • 5/Cas209 IR-88 210 BC,Fo rs,so Mil yang 23, 5/Cas209

Xa-11 !R-88 I I BC,F, !S618 IR24 • 5/lRS IR-BB 11 l BC.F, !S627 TO)'Onishiki • 5/!R8 IR-BB 211 BC,F, !S624 Milyang 23 • 5/ !RS

a): No1 scgrcga1cd.

76

2

2

JARQ 27(2) 1993

3 4

I fl 24

3 4

5 6

5 6

2 3 4

IR-BB 3

2 3, 4

5 6 2 3 4

I R-8 B 4

5 6 2 3 4

I R-8 B 5 IR-BB 7 Pl 231129

l'la1r I. Rcac1 ion or ncar-isogcnic line~ and rcprescma1ivc cuh ivars 10 Philippine and Japnncs,c rncc~

5 6

5 6

continued)

2 3 4

I R24/AUS274

T N

Nore: The numbers on 1op indicate 1hc rcspCCli"c races from !he Philippines (except for Japanese race I R- 13B 11 ). IR24/ AUS274 FJ indicates the reaction of 1hc segregant from 1hc cross between IR24 (susceptible) and i\US274 (xa-5, .m - 13 ). The plant carries only 1hc .,·a-I J gene.

77

78

addition, X{l-/" and X{l-/2h were reponed to be al lelic genes of X{l- 1 and Xa-12. Analysis using IR28, IR29, and lR30 showed 1ha1 these cul1ivars harbor Xa-4, which is also effective against the Japanese isolates. Therefore, Xu-I h and Xa-12 11

should be compared with Xa- 1 and Xa- 12 based on !he resistance gene Xa-4 of IR28, IR29, and IR30 10 Japanese isolates.

3) Resistance genes recently identified During 1he research collaboration between Japan

and IRRI, two new genes, xa-13 and Xa-14, were identified using Phi lippine races11·29>. xa-13 in BJ!, ACI9- 1- I, AUS274, Chinsurah Boro II, and Kalimakri77-5 is resisian1 only to race 6 of the Philippines1 •>. Xa- 14 in Taichung Native I is resis­lalll only 10 race 5 of the Philippines29>. However, ii. has 1101 been determined whether the two genes arc resistant to the Japanese isolates. Allhough 1hc presence of a recessive gene, xa-15 (a mucant from Harebare), was reported, ii has 1101 been confirmed ycl because no allelic 1cs1 with known recessive genes&> was conducted.

Xa-16 in Tc-1ep, and Xa-17 in Asominori were identified using Japanese isolates7•121 , whi le Xa-18 in Toyonishiki, Milyang 23, and IR24 was identi­fied using a Myanmar isolatcJJ>.

Two recessive genes, xa-19 and xa-20, were induced in I R24 by N-methyl-N-ni1roso-mea (MNU)27

•28>. The two genes were resistant to all 1he Philippine races.

The latest resistance gene identified is Xa-21, which was introduced inco I R24 by backcrossing from a wild rice variety, 0. /011gista111ill(lltr>. The resistance genes 10 bacterial leaf blight recently iden­tified are summarized in Table 3.

Breeding of near-isogenic lines

Near-isogenic lines with various genes for resistance to major diseases and insects can be useful for iden­tifying races and biotypcs of diseases and insects as well as new genes fo r resistance. Moreover, isogen­ic lines can serve as donors of resistance in breeding programs and be excellent materials for smdying the mechanism of resistance. In !he case of rice diseases and insects, no near-isogenic lines can be used as common differentials internationally due to the difficulty in exchanging materials among rice-growing

JARQ 27(2) 1993

countries. To establish a common basis of research on

resistance to bacterial leaf blight, attempts were made to develop near-isogenic lines with diverse genes for the re.sistance 10 1he disease under the above collabo­raiion. As a result, the initial se1 of near-isogenic lines (more advanced generation than BC.F.) was ceveloped using IR24, Milyang 23, and Toyonishiki as recurrelll pare111s (Table 4)19>

Slrategy for moniloring race distribution and identification of new genes

I) Proposed intemationaf differentials for bacterial leaf blight pathogen.

The near-isogenic lines were developed with I R24 for use as international differentials 10 1he bacterial kaf blight pathogen and as testers to identify new resistance genes 10 !he disease. However, the genes recc111ly identified are 1101 related 10 these lines be­cause the breeding of near-isogenic lines carrying the new resistance genes is currently underway.

Therefore, il is recommended to use the lines and

Table 5. Pro11osed in lcrnalionnl diffcrenlials f'or monitor­ing !he race clislribution of !he bacterial lc,1f bllghl pathogen

Diffcrcncials Ecotypc

l ' roposcd i111crnational differentials : Toyonishiki Japonica IR24 lndica JR - Bil I lndica IR- BB 2 lndica IR- BB 3 lndica IR- 138 4 lndica TR- Bil 5 l ndica IR-B8 7 lndica IR-B8 8 l ndica IR-B8 10 lndica IR-B8 11 lndica IR- 138 21 •l lndica BJ ! lndica Taichung Na1ivc lndica /\sorninori Japonica

Op1ional differentials: M4lb> Japonica XM.5 '> XM6 '>

a): Newly dcvclopcdJ>. ~): Muiam from Harebare. c): Mumm from IR24.

Rcsis1ancc gc.nc

X(l-/8 X«- 16 Xo- J, Xa- 12 X11-2

X"-3 Xfl-4 x«-5 Xo-7 xa-8 Xa- 10 Xa-11 Xa-21 xn- 5, xo- lJ Xu-14 Xa- 17

(xo-/5) xa-19 Xll-20

cultivars shown in Table 5 ror monitoring I he race distribution or the baccerial lcar bligl11 pathogen.

By using the 18 cull ivars listed above, ic is likely , hat mosc races could be identified and effcccive resistance genes could be recognized in each country.

2) Me1hods for fdentificatio11 of a new resis1auce

gene f'or the idcn1irication of a new resistance gene LO

bacterial leaf blight, che following seeps arc recom­mended:

Step I: Comparison of reaction pattern; the above 18 differentia ls should be subjected co inoculation ccscs cogct her wich che rcsis1an1 cult ivar where the resistance gene is expected 10 be idcnti J'ied. If the reaccion of the resistant cultivar is clearly differen t from that of the differentials and if it is confirmed that the resistant cullivar carries only one resistance gene in Stc1, 3, the resistan t cull ivar can be consi­dered Lo carry a new resiscancc gene.

Step 2: Hybridization; it is always necessary to obtain the F1 hybrids between resistant and suscept­ible cullivars.

Stc1> 3: Determination of the number or resistance genes; by breeding the F2 population between sus­ceptible and resistant cultivars, the number of rcsisiance genes in the resistant cuhivar should be estimated from the ratio of segrega tion in the popu­lation.

S1e1> 4: Allelic test with domina111 genes; when the FI hybrids obtained in SteJ> 2 are resistant to the isolates, it is necessary to develop F2 hybrids between the resistant cuhivar and the above differentials wll'ich carry dominant genes and show a similar reaction to that of 1hc tested resistant cu l1ivar. If suscepti­ble plants arc clc1ec1ed in every F2 populacion, 1he resisca111 cull ivar can be considered to carry a new resistance gene.

Step 5: Allelic test with recessive genes; when the F, hybrids obta ined in S1e1> 2 arc susceptible, the resismnl cult ivar should be crossed with differentials, which carry a recessive gene and show a similar reac­tion 10 that of che resistan t cultivar. to obtain the F1 hybrids. If every F1 hybrid is susceptible co the isolates, it is assumed that the resistant cultivar car­ries new resistance gene.

If there is more than one resistance gene in the tested resistant cultivar in Step 3, a similar proce­dure should be adopted from Step l onward except

79

for Stc11 3 arcer obrnining segregan,s carrying only one resistance gene from the hybridization between ~usccptiblc and resistant cultivars.

Resisrnnce reactions o f cull ivars

There are various kinds or resistance reactions to 1hc bacterial leaf blight pathogen in rice cult ivars. Usually, it is recommended 10 observe rice plants dur­ing 2 10 4 weeks after inoculation by applying the clipping method. Sui table concentracion of bacter­ia for inoculation may be 108 cells/ml. The resis-1ant plants show a lesion length below about 6 cm at 3 weeks after inoculation. However. the reactions vary depending on the virulence of the inoculum, wea1her conditions. planl age, etc.

The resistance reactions of cultivars can be classi-1 ied into the following categories. I . Highly resistant; no or minimal lesion deve lop­ment after inoculation (reaction of cultivar with Xa-10 gene to Phi lippine race 2). 2. Resistant; lesion length below about 6 cm at 3 weeks after inoculation (reaction of cultivar wich Xa-4 gene to Philippine race I) . 3. Resistant with lesions showing a brown margin; lesions arc less than abouc 6 cm long ac 3 weeks af­cer inoculation and thcy are characterized by a brown margin or spots around the lesions (reaction of cul­civar wiih Xa-3 gene to Philippine races I to 4).

4. Moderately resistan t or susceptible, i.e. variable; lesions continue 10 develop af1er inoculation, but more slowly than in che case or the susceptible cuhi­\ars (reaction of cult ivars with Xa-4 and :<a- 5 genes 10 Philippine race 4).

5. Susceptible; lesions continue to develop after in­oculation. These reaccions are illustrated in Plate I.

References

I) fauka, A. c1 al. (1975): lnhcri1ance of resistance. or rice varic1y Wasc /\ikoku 3 10 Xan1ho11101ws oryr.ae. Bull. TOk(li-Ki11ki N(I(. llgr. E.1·11. S((J., 28, 124-130.

2) Jayaraj, D. cl al. (1972): Genetics of rcsis1ancc 10 bac· aerial leaf bligt11 in rice. Indian J. Genet. Plam Breed., 32, 77-89.

3) Khush. G. S. Cl al. (1990) : A new gene for resisrnncc 10 bac1crial bligl11 from 0. /011gista111i11at/l . Rkc Gene/. Nell's/., 1, 121-122.

4) Librojo, v. c1 al. (1976): Genetic analysis of bac1crial blight resistance in four varieties of rice. SIIBRIIO J., 8, 105- 110.

80

5) Moses. C. J. e1 al. (1974): lnhcrilance or resistance 10 bac1erial bligh1 in rice. Indian J. Ge11e1. P/1J111 IJreed .. 34 . 27 1-279.

6) Nakai, H. Cl a l. (1988): S1udics on murntion breedi ng or rice for bac1crial leaf blight resistance. 6. Dciermi -11atio11 of gene of the resista111 M4 1 111uta11110 the 111ul -1iple races. Jpn. J. /Jreed., JS (suppl. I), 290- 291 ! In Japa,1escJ.

7) Noda, T. & Ohuchi, A. (1989): A new pa1hogcnic race o r Xa111homo11as c,1111pes1ris pv. ory:u,e and inheri1ancc or resistance w 11. 111111. Phy1opa1lt. Soc·. Jpn. , 55, 201-207.

8) Ogawa. T . ct al. ( 1978): Inheritance or resisiance 10 rice varic1ies Kogyoku a nd Java 14 10 bacterial group V or X"111homonas orywe. Ann. Phy1ov<1th. Soc. Jpn., 44 , 137- 141.

9) Ogawa, T . & Yama mo to, T. ( 1986): Inheritance of resistance of bac1erial bligh1 in rice. /11 Rice genetics. IRR I, Manila, 47 1-479.

10) Ogawa, T. (1987): Gene symbols for resistance 10 bac-1crial lcar bligh1. Rice Genet. News/. , 4, 4 1- 43.

II) Ogawa, T. Cl al. (1987): A new recessive gene for resistance 10 bac1cl'ial blight or rice. Ric'e Ge11e1. News/ .. 4 , 98- 100.

12) Ogawa. T . ct al. (1989): Rcsis1ancc gene or rice cu hi­var, l\sominori 10 bacterial blighc o r rice. Jp11. J. IJreed .. 39 (suppl. I), 196- 197 (1 11 Japanese].

13) Ogawa, T . & Khush, G. S. (1989): Major genes for resistance to bacterial blight in rice. /11 Oacccria l blight of rice . IRRI, Manila, 177- 192.

14) Ogaw.i, T . ct al . (1990) : Genetics or resista nce in rkc cuh ivars, Chugoku 45 a nd Java 14 10 Philippine a nd Japanese races or bac1erial blight pathogen. Jp11. J. Breed .. 40. 77- 90.

15) Ogawa, T. Cl a l. ( 1990) : Genetics of resisiance in rice cul1ivars. Zenith and Cern po Selak 10 Phi li11pine and Japanese races or bac1crial blight pat hogcn. Jpn. J. IJreetl., 40 , 183- 192.

16) Ogawa, T. c1 a l. (1990): Ocnc1ics or resistance in rice cultivars Salcng 10 Philippine and Japanese races or bacterial blight pachogen. Jpn. J. Breed., 40, 329-338.

17) Ogawa, T. CL al. (1990): Genetics of resista nce in rice cultivars, I R20 and Scmora Mannga 10 Philippine a nd Japanese races or baccerial bligh1 pa1hogcn. Jpn. J. Breed. , 40 , 435-447.

18) Ogawa, T . Cl al. (199 1): Resistance and its inheritance 10 bacterial blight or I R8 rice cuhivar grou1>. Jpn. J. Bri!ed., 4 1, 211- 221.

19) Ogawa, T . Cl al. ( 1991): Breed ing ncar-isogcnie lines or rice with single gene$ for resistance to bacterial blight pathogen ( X11111ho11101111s c11111pe.s1ris pv. orywe) . Jpn. J. Breed .. 41, 523-529.

20) 0111rowo1c. J . O. ct al. ( 1977) : h1heri1ance or bac1cri­al bliglu resis1ance in rice. Phy101>111h1/l<>gy, 67,

J A RQ 27(2) 1993

772- 775. 21) Pc1pisil , V. ct a l. ( 1977): Inheritance of resistance or

bac1eri.1I blight in rice. Crop Sci .. 17, 551 - 554. 22) Sakaguchi. S. (1967): Linkage studies 011 1he resistance

to bac1eria l lea f bliglu, Xa111ho111011as orywe. 8111/. N/l(. / 11s1. Agr. Sci., Jpn., Ser. 016. 1- 18 lln Ja11ancsc with English summary].

23) Sidhu , G. S. & Khush, G. D. ( 1978): Dominance rever­sal for a bacterial blight resistance gene in some rice cuh ivars. Phy1op1,1hology. 68, 461-463.

24) Sidhu, G. S. c1 al. (1978): Genetics analysis or bac­teria l blight resistance in scvcmy-four cuhivars or rice, Ory7.a satiM L. Theor. Appl. Ge11e1., 53, 105- 111.

25) Sidhu, 0. S. c1 al. ( 1979) : Genetics analysis of bac­teria l blight in seventy cuh ivars or rice, Oryw sa1i11a L .. from Indonesia. Crop. /111pro11., 6, 19-25.

26) Singh, R. J. c1 al. (1983): A new gene for resista nce 10 bacterial blight [n rice. Crop Sci., 23, 558-560.

27) Taura, S. ct al. (199 1): ldcn1irica1ion of a recessive gene in ind uced mu1a111 line XM5 or rice 10 bacterial blighL. Jpn. J. B,·ee<I. , 4 1, 427-432.

28) Taura. S. ct al. (1992): ldcn1 ifica1 io n of a recessive gene 10 rice bacterial blight of mutant line XM6, Ory;:.11 s<11iw, L. Jpn. J. IJreed. , 42 , 7-13.

29) Taura, S. c1 al. ( 1992): Resis1ance gene of rice cuhi­var, Taichung Native I 10 Philip1)inc races or bacterial blight pathogens. Jpn. J. Br<!<:d., 42, 195-201.

30) Washio , 0. e1 al. (1966): S1udics on breed ing rice var­ielies for resistance co bacterial leaf blight. /J11//. Ch11gok11 Agr. Ew. Sw. Ser. I\ 13, 5S-85 [In Japanese with English summary].

31) Watanabe, S. ( 1976): Studies on the breeding of rice variecics rcsis1a111 10 baeccrial leaf blight in Sri Lanka. Tohoku N(I/. Agr. Exp. Sw .. 54 l ln Japanese with English su mmary!.

32) Yamada, T . (1984): Mulliplc a lleles a1 the Xa- 1 a nd Xa-kg loci for resistance lo bacterial lcar b light. Rice Genet. News! .. I, 97-98.

33) Yamamoto, T . & Ogawa, T. (1990): Inheritance of resistance in rice culc ivars, Toyonishiki, Milyang 23 a nd I R24 10 Myanmar isolates or baccerial lcar blighc pa1ho­gcn . JARQ. 24, 74-77.

34) Yoshimu ra , A. Cl al. ( 1983): Inheritance of resistance lO bacterial bligh1 in rice cuhivar Cas209. Phylopathol­ogy, 73, 1409- 1412.

35) Yu. G. X. ct al. (1986): Locacion or genes for resistance 10 Chinese strains of bacterial blight. Xa11-lhomonas campestds pv. orywe in I R28. Rice Gene,. News/., 3, 86-87.

36) Zhao, X. P. c1 al. (1985) : Studies on the inheritance or rice 10 bacteria l blight . J. f fl({ld1011g Agr. Coll., 3, 11-22 [I n Chinese wi th English summary].

(Received for publ ica1ion, Dec. 7, 1992)