Postulation of Seedlings Resistance Genes to Yellow Rust in Commercial Wheat Cultivars from Yunnan Province in China

Agricultural Sciences in China

November 2011

2011, 10(11): 1723-1731

Postulation of Seedlings Resistance Genes to Yellow Rust in Commercial Wheat Cultivars from Yunnan Province in China LI Ming-ju1, 2, FENG Jing1, CAO Shi-qin3, LIN Rui-ming1, CHENG Geng4, YU Ya-xiong4, CHEN Wan-quan1 and XU Shi-chang1 State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, P.R.China 2 Institute of Environment and Resources, Yunnan Academy of Agricultural Sciences, Kunming 650205, P.R.China 3 Institute of Plant Protection, Gansu Academy of Agricultural Sciences, Lanzhou 730070, P.R.China 4 Institute of Food Crops, Yunnan Academy of Agricultural Sciences, Kunming 650205, P.R.China 1

Abstract The objective of this study was to characterize yellow (stripe) rust resistance gene(s) in 52 commercial wheat cultivars from Yunnan Province in China, and to provide information for their rational deployment in field. Seedlings of wheat cultivars were inoculated with 25 differential isolates of Puccinia striiformis from foreign and home to postulate resistance genes to yellow rust, and then validated by pedigree. There were 10 probable resistance genes characterized in these cultivars, in which, Yr9 was most commonly postulated to be present in thirteen cultivars. Yr21, the second, was present in four cultivars. Yr8, the third, were present in three cultivars. Yr6, Yr17 and Yr26, the fourth, was present in two cultivars respectively. The other gene(s) such as, Yr2+YrA, Yr7 and Yr27, were only present in single cultivar(s); unknown gene(s) or gene(s) combination(s) were present in 22 cultivars. One cultivar (Yunmai 42) had no resistance gene tested in this study. Cultivars such as Yunmai 52, Mian 1971-98, Kunmai 4, and Yunmai 56 carried effective genes and can be popularized mainly; Yr9 should be planted with other Yr genes. In the meantime other effective genes should be introduced to realize gene diversity for controlling wheat yellow rust. Yunmai 42 should be reduced to avoid rust breakout. Unknown gene cultivars should be utilized and be researched deeply. Key words: wheat cultivars, yellow (stripe) rust, resistance genes, gene postulation

INTRODUCTION Wheat yellow (stripe) rust, caused by Puccinia striiformis Westend f. sp. tritici Eriksson, is a destructive worldwide wheat disease (Li and Zeng 2002; Zeng and Luo 2006). It distributes in 6 continents over 60 countries and causes yield losses 10-70%, even 100% (Chen 2005). China is the biggest epidemic zone of wheat yellow rust in the world and the disease often

Received 12 November, 2010

causes huge economic losses in years of outbreaks (Li 2004; Wan et al. 2007; Chen et al. 2007, 2009). Yunnan Province is one special region where the pathogen is very complex and can live through summer and winter easily (Wu and Niu 2000; Ma et al. 2005). It is deduced that Yunnan is the probable original pathogen base of wheat yellow rust in China (Zhou et al. 2006). As an important guarantee for food security of China to control the yellow rust, breeding and releasing resistance cultivars has been the most effective, economi-

Accepted 28 February, 2011

LI Ming-ju, Ph D candidate, Tel: +86-10-62815946, E-mail: [email protected]; Correspondence FENG Jing, Ph D, Associate Professor, Tel: +86-10-62816081, E-mail: [email protected]; CHEN Wan-quan, Professor, Tel: +86-10-62815903, E-mail: [email protected] © 2011, CAAS. All rights reserved. Published by Elsevier Ltd. doi:10.1016/S1671-2927(11)60171-5

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cal and environmentally friendly approach (Wu et al. 2000; Li and Zeng 2002; Li 2004; Chen et al. 2009). Characterizing yellow rust resistance gene(s) of commercial cultivars in Yunnan can guide on the breeding and gene deployment. Flor’s gene-for-gene theory (Flor 1971) provides base for resistance gene postulation, so it is widely used on gene analysis to yellow rust (Dubin et al. 1989; Wang et al. 1994; Sharma et al. 1995; Niu et al. 2000; Ochoa et al. 2007; Hovmøller et al. 2007; He et al. 2007; Amin et al. 2008; Feng et al. 2009; Ren et al. 2010), leaf rust (Yuan et al. 2007), stem rust (Qiu et al. 1999) and powdery mildew (Xue et al. 2009). Gene postulation has been studied in special yellow rust since the 1980s, Such as CIMMYT (Dubin et al. 1989), Nepal (Sharma et al. 1995), France and Holand (Hovmøller et al. 2007; Pathan et al. 2008), Ecuador (Ochoa et al. 2007) and China (Wang et al. 1994; Niu et al. 2000; He et al. 2007; Feng et al. 2009; Ren et al. 2010), etc. A lot of genetic information of cultivars can be got in a short time. Postulation of resistance genes to stripe rust in commercial wheat cultivars from Shanxi, Gansu, Sicuan, Henan, Shandong, and Anhui provinces in China have been done (Wang et al. 1994; Niu et al. 2000) except Yunnan cultivars. So in this study, we will postulate the presence of Yr genes in Yunnan commercial wheat cultivars in order to provide information for its national use.

MATETIALS AND METHODS Experiment time and place This study has been done in the green house of the Institute of Plant Protection (IPP), Chinese Academy of Agricultural Sciences (CAAS) in 2009.

Wheat cultivars The cultivars used in this study included 52 cultivars, a set of differential hosts (contained 33 cultivars) from international, European and Chinese, and additional testers with known Yr genes, provided by IPP, CAAS. Seed samples of wheat for test were generally provided by the Institute of Food Crops (IFC), Yunnan

LI Ming-ju et al.

Academy of Agricultural Sciences, China (YAAS).

Pathogen materials Twenty-five P. striiformis f. sp. tritici isolates, including race 40E25 (Netherlands), 237E25 (Israel), 33E158 (Netherlands), 32E16 (Egypt), 105E177 (Germany), 40E154 (Netherlands), 32E17 (France), 41E185 (Kenya), 44E25 (Ecuador), 108E185 (Afghanistan), 109E24 (Pakistan), 35E182 (Ethiopia), 99E158 (Netherlands), 108E249 (Chile), 65E176 (Netherlands), 2E16 (Chile), 35E150 (unknown), 2E24 (unknown), 99E20 (unknown), 3E22 (China, CYR17), 12E89 (China, CYR26), 99E16 (China, CYR27), 171E191 (China, CYR29), 102E25 (China, CYR31), and 195E220 (China, CYR33) were chosen on the basis of their virulence spectrum to differentials. The race nomenclature was based on the proposal by Johnson et al. (1972) and depended on the selection of a standard set of differential cultivars. These races that possess a wide range of pathotype (virulence) were provided by IPP, CAAS, and were increased on Mingxian 169 which is highly susceptible to yellow rust races in greenhouse.

Inoculation and disease assessment Follow the method (Wang et al. 1994; Niu et al. 2000; Feng et al. 2009), the test cultivars seeds 8-10 per cultivar per hole were grown in standard peat soil in 35 cm×24 cm square box in all 40 cultivars according to some order. A set of cultivars including susceptible cultivar Mingxian 169, known gene lines and test cultivars had three boxes. There were 25 sets of it in total. When their first leaves were fully expanded, about 14d-old, they were inoculated by “sweep-dusting” method, with a very uniform deposit of spores. A set of cultivars was inoculated by an isolate. Plants were incubated for 24 h in darkness at 10°C and relative humidity at saturation which contribute to the fungal infection. They were then transferred to a growth chamber at 14/ 18°C (night/day), with 6 000 Lux of light intensity and a 14-h photoperiod. When the susceptible check, Mingxian 169 was heavily infected, about 14 d after inoculation, infection type (IT) on the seedlings was recorded using a 0-4 scale.

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Postulation of Seedlings Resistance Genes to Yellow Rust in Commercial Wheat Cultivars from Yunnan Province in China

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isolates 171E191 and 19E220, but immune to other isolates. There were 8 cultivars that their resistance spectrum was same to Avocet S*6/Yr9. So we thought they also carry Yr9 gene. These cultivars were Yunmai 53, Fengmai 37, Feng 05-394, Jing 06-4, Chumai 10, De 05-81, Liangmai 4, and Yimai 2003-13. There were 5 cultivars, such as, Yunza 7, Kunmai 5, Jingmai 11, Jing 0202, and Linmai 6, whose resistance spectrum was similar to Avocet S*6/Yr9 but IT much lower to isolate 171E191 or 19E220. We thought they carry Yr9 and other genes. Looking at pedigrees, it has been found that only Jinmai 11 has a parent Kavkaz with Yr9 (Wang et al. 1994; Niu et al. 2000), and the other cultivars cannot be verified by pedigree.

Effective Yr gene can’t be differentiated (Yr5, Yr10, YrMor, Yr15, and Yr26)

RESULTS Seedling ITs of known gene cultivars to 25 isolates were listed in Table 1. Test cultivars with probable gene and its ITs to 25 isolates were listed in Table 2. In this study, CK cultivar Mingxian 169 has high ITs to all test isolates, indicating that inoculation is successful. It is known that Mingxian 169 has no Yr gene. Ten probable resistance genes characterized in these cultivars, in which, Yr9 was most commonly postulated to be present in 13 cultivars. Yr21, the 2nd, was present in 4 cultivars. Yr8, the 3rd, were present in 3 cultivars, Yr6, Yr17, Yr26, the 4th, was present in 2 cultivars respectively. The other gene(s) such as, Yr2+YrA, Yr7 and Yr27, were only present in single cultivar(s); unknown gene(s) or gene(s) combinatio(s) were present in 22 cultivars. One cultivar (Yunmai 42) had no resistance gene tested in this study.

Cultivars carry Yr9 Avocet S*6/Yr9 (carry Yr9) was highly susceptible to

Yr5, Yr10, YrMor, Yr15, and Yr26 were resistant to all isolates, so the test isolates cannot differentiate these Yr genes. Yunmai 52, Kunmai 4 and Yunmai 56 were immune to all test isolates, so we could not differentiate what gene they carried. Mian 1971-98 was immune to all isolates except to 32E16 (IT was 1). Tracimg their pedigree, we found Yunmai 52 was 92R149/963-11185, and Mian 1971-98 was 96-18-6/ 92R178. 92R149 and 92R178 were from WheatHaynaldia villosa 6AL/6VS chromosome translocation lines breeded by Nanjing Agriculture, and carried Yr26 (from cone wheat γ80-1) (Ma et al. 2001). Parents of Yunmai 52 and Mian 1971-98 carried Yr26, so they might also carried Yr26. Kunmai 4 and Yunmai 56 can not be verified by pedigree, so we could not know what gene it carried, but it is effective Yr gene by now.

Cultivars carry Yr21 or other gene(s) The resistance spectrum of Fengmai 39, Yimai 10, Yunmai 48, and Jingmai 12 was similar to that of Lemhi (Yr21), but the former ITs were lower than Lemhi to some of isolates. We thought the four cultivars carried Yr21 and other gene(s). Fengmai 34, Fengmai 38 and E33, their resistance spectrum is similar to Avocet S*6/Yr8 (Yr8), but some isolates ITs were lower than Avocet S*6/Yr8, we though

© 2011, CAAS. All rights reserved. Published by Elsevier Ltd.

Chinese 166 Sonalika Heines Kolben Heines VII Virmorin23 Nord Desprez Mega Hybrid 46 Avocet S*6/Yr6 Avocet S*6/Yr7 Lee Avocet S*6/Yr8 Compair Avocet S*6/Yr9 Clement VPM1 Lemhi K733 Tp981 Strubes Dickkopf Selkirk T. tauschii W-219 Carstens V Suwon 92/Omar Spalding Prolific Jubilejina II Kangyin 655 T. spelta album Avocet S*6/Yr5 Avocet S*6/Yr10 Moro Avocet S*6/Yr15 Line R55 MX 169

1 3 5 7 8 9 11 12 13 14 15 17 18 19 20 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40

1 2, A 2, 6 2, HVII 3, 23 3, + 3, 4 4, + 6 7 7, 22, 23 8 8, 19 9 9, Cle 17 21 24 25 25, SD 27 28 32 Su SpP Jul-4 Ky1-2 5 5 10 10, Mor 15 26 no

Yr gene

0 3 2 0; 3 3 3 3 0; 0; 0; 0; 4 0 0 2 3 0 3 4 3 0; 2 0 0 0 0 0 0 0 0 0 0; 4

40E 25

0 3 3 0; 3 3 3 3 0; 0; 0; 1 3 0 3 0; 0 0 4 3 0; 0; 3 0 0; 0 0 0 0 0 0 0; 4

237E 25

4 3 0; 3 2 4 0; 0; 3 3 0 4 4 0 0 0; 3 0; 3 4 2 3 0; 0; 0 0 0 0; 0 0 0; 0 0; 4

33E 158 0; 4 1 2 1 0; 0; 2 3 4 0 4 4 0 0 0; 3 3 0; 3 3 0; 0; 0 0; 0 0 0; 0 0 0; 0 0; 4

32E 16 4 3 2 3 3 1 1 3 2 2 0; 3 3 0 0; 3 3 3 0; 4 3 0; 4 4 0; 0; 0 0; 0; 0 0; 0 0; 4

105E 177 0; 4 0; 3 3 3 3 0; 0; 0; 0; 0 4 0 0 2 4 0 3 4 3 0 0 0; 0; 3 0 0 0 0 0 0 0; 4

40E 154 0 4 0 0 0 0 4 4 0; 0; 0 0 4 0 0 0 0 1 0 4 0 0 0 0 0 2 0 0 0 0 0 0 0 4

32E 17 3 4 2 3 3 3 2 3 2 0; 0; 0; 3 0 0 2 3 3 2 4 3 0; 4 0; 0; 0; 0 0; 0; 0 0; 0; 0; 4

41E 185 0; 3 3 2 3 4 3 3 3 1 0; 0; 4 0 0; 3 4 0; 3 4 3 0; 2 0 0; 0; 0 0; 0; 0 0 0 0; 4

44E 25 0; 3 3 3 3 3 3 3 0; 0; 2 0; 4 0 0 3 4 3 0; 3 2 0; 3 3 0; 0; 0; 0; 0 0 0; 0 0; 4

108E 185 3 3 3 2 3 3 3 2 3 3 0; 3 4 0 0 2 4 3 0; 4 3 0; 0; 4 0 0 0 0 0 0 0 0 0; 4

109E 24

-, no data available; +, unknown gene or gene(s) combination(s). T., Triticum; MX 169, Mngxiang 169. The same as below.

Cultivars

No. 4 3 2 4 0; 2 3 2 0 3 2 0; 4 0 0 0; 4 4 0; 4 3 0; 4 0; 0; 4 0 0; 0 0 0 0 0 4

33E 182

Table 1 Seedling ITs of cultivars with known genes inoculated with 25 isolates of P. striiformis f. sp. tritici

3 4 2 4 2 3 3 2 4 4 3 0; 4 0 0; 3 4 3 0; 4 4 0; 2 3 0; 3 0; 0; 0; 0 0 0 0; 4

99E 158 0 0 3 3 3 4 0 4 4 0; 0; 0; 4 0 0 0; 4 3 0 3 3 0; 3 4 3 0; 0 0 0 0 0 0 0; 4

108E 249 4 3 1 3 2 2 3 1 1 1 2 2 4 0 0; 3 4 0; 2 0 3 0; 4 4 0; 0; 0 0; 0 0 0 0 0; 4

65E 176 0 0; 0 0; 1 0; 0; 0; 1 2 3 3 3 0 0 0; 0; 0; 2 2 2 0 0; 0; 0 0 0 0 0 0 0; 0 0; 4

2E 16 3 3 1 3 0; 0; 0; 0; 3 3 3 4 4 0 0 2 3 3 0; 4 3 0; 0; 0 0; 3 0 0 0 0 0; 0 0; 4

35E 150 0; 3 0; 0; 0; 0; 0; 0; 3 1 3 4 4 0 0 0; 3 0 1 0; 3 2 0; 2 0 0 0 0 0 0 0; 0 0 4

2E 24 3 3 0; 1 0; 0; 0; 0; 3 3 3 4 4 0 0; 0; 3 3 1 3 2 0; 0; 4 0 0 0 0; 0 0; 0 0; 4

99E 20 3 4 0; 1 1 1 1 0; 3 3 3 3 4 0 0 4 4 0; 1 0 3 0; 0; 0 0 0 0 0; 0 0 0 0 0; 4

3E 22 0 4 4 0; 4 4 0; 4 0; 1 0; 0; 3 0; 0 4 4 0; 3 2 2 0; 1 0 3 0 0 0; 0 0; 0 0 0; 4

12E 89 0 3 0; 0; 0; 0; 0; 0; 1 0 3 3 3 0 0 2 1 1 0 3 3 0 0 4 0 0 0 0 0 0 0; 0 0; 4

99E 16 4 4 2 4 4 4 4 3 4 4 3 4 4 4 4 4 4 3 4 4 4 0; 4 0 0 2 0 0 0 0 0 0 0 4

171E 191 0; 4 3 2 0; 3 0; 3 3 3 3 3 4 0 0; 3 3 0 1 4 3 0; 0; 4 0; 0 0 0 0 0; 0; 0 0; 4

4 4 1 4 2 4 0; 0; 4 3 3 0 3 4 4 4 4 4 0 2 3 0; 0; 4 4 4 4 0 0 0 0 0 0 4

102E 195E 25 220

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Cultivars

Yunmai 53 Fengmai 37 Feng 05-394 Jing 06-4 Chumai 10 De 05-81 Liangmai 4 Yimai 2003-13 Yunza 7 Kunmai 5 Jingmai 11 Jing 0202 Linmai 6 Fengmai 39 Yimai 10 Yunmai 48 Jingmai 12 Fengmai 34 Fengmai 38 E33 Yunxuan 3 06D6-6 Yunmai 54 017-10 R101 Wenmai 12 Linmai 15 Yunmai 42 Yunmai 52 Mian 1971-98 Kunmai 4 Yunmai 56 Yunmai 43 Yunmai 47 Yunmai 51 Yunmai 57 Yunmai 101 Yunxuan 11-12 Kun 022-222-1 Fengmai 35 Fengmai 36 Fengyin 03-2 Feng 1124 Jingmai 14 Demai 3 Demai 7 Chumai 12 Yimai 2003-27 Wenmai 11 02D2-282 91E001 R57

No.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52

9 9 9 9 9 9 9 9 9, + 9, + 9, + 9, + 9, + 21, + 21, + 21, + 21, + 8, + 8, + 8, + 6, + 6, + 17, + 17, + 2, A, + 7, + 27, + no 26 26 + + + + + + + + + + + + + + + + + + + + + +

Yr gene

40E 25 0 0; 0; 0 0 0 0; 0 0; 0 0 0 0 0 0; 0 3 0 0 0 0 0 0 0 3 0 0 4 0; 0; 0; 0 3 4 3 0; 0; 0; 2 0 4 3 0 0; 0 0 0; 4 3 2 0

237E 25 0 0 0; 0; 0 0 0 0 0; 0 0 0; 0 0; 0; 3 3 0 0; 0 0; 0 0 0 0; 0 0; 4 0; 0; 0; 0 3 3 0 0 0 0 0; 3 0; 4 3 0 0; 0 0 0; 0 3 3 0

33E 158 0 0 0; 0 0; 0; 0 0; 0 0 0; 0 0 0; 0; 0 0 0; 1 0 0 3 0 0 2 0 2 4 0; 0; 0; 0 3 4 0; 0 0 0; 3 3 0 4 3 0 4 0 0 2 0 3 2 0

32E 16 0 0 0; 0; 0; 0; 0; 0 0; 0; 0; 0 0 3 2 0; 0 4 0 0 0; 0 0 0 0 0 3 4 0; 1 0; 0 4 4 3 0 0 0 0 4 3 3 3 0; 4 0 0 4 0 4 4 0

105E 177 0 0; 0; 0; 0; 0; 0; 0; 0; 0; 0 0; 0 0; 0; 3 0; 0; 3 0 0; 0; 0; 0; 0 2 0; 4 0; 0; 0; 0; 3 4 0 4 0; 0 0; 3 0; 4 3 0; 3 0 0; 2 0 3 2 0;

40E 154 0 0 0 0 0 0; 0 0 0; 0 0 0 0 0; 0; 0 0 0 0; 0 0; 0 0 0 4 0 0 4 0; 0; 0 0 4 4 4 0; 0 0 0 4 4 4 3 4 3 0 0; 0; 0 3 0; 0;

32E 17 0 0; 0 0 0 0; 0 0 0 0 0; 0 0 0; 0; 0; 0 0 0; 0 0 0 0; 0 3 0 0 4 0 0; 0 0 3 3 0 0; 0; 0; 0; 3 3 4 1 0; 3 0 0 0; 0 3 2 0;

41E 185 0; 0; 0; 0; 0; 0; 0; 0; 0; 0 0; 0; 0; 0; 0; 0 3 0; 0; 0; 0 0 0; 0 0 0 0; 4 0; 0; 0; 0; 3 4 3 0 0 0 0; 2 0; 4 3 0; 3 0 0 2 0 2 2 0;

44E 25 0 0; 0; 0; 0; 0 0; 0; 0; 0 0; 0; 0; 0; 0; 0; 0 0; 0; 0; 0 0; 0; 0 0; 0 0; 4 0; 0; 0; 0 3 4 3 0; 0; 0; 3 3 0; 4 3 4 3 0 0 3 0 3 2 0;

108E 185 0 0; 0 0 0; 0 0 0 0; 0 0 0 0 4 0; 4 0 0 0 0 0 0 0 0; 0 0 0; 4 0; 0; 0; 0 4 4 4 4 0 0; 0; 4 0; 4 0; 0 3 0 0 0; 0 4 2 0;

109E 24 0 0 0; 0 0 0 0 0 0; 0 0 0 0 0; 0; 0; 0 0 0; 0 0 0 0 0 2 3 0; 4 0; 0; 0; 0 4 4 4 0; 0; 0; 0; 3 3 4 4 0 3 0 0 1 0 3 3 0;

Table 2 Seedling ITs of wheat cultivars tested to 25 isolates of P. striiformis and their postulated Yr genes 33E 182 0 0 0 0 0 0 0 0 0; 0 0 0 0 0 0; 0 0 0 0; 0 0 0 0 0 3 0 0; 4 0 0; 0; 0 2 4 0 4 0 0 0 3 0; 4 3 0 2 0 0 2 0 2 1 0;

99E 158 0 0; 0; 0; 0; 0 0; 0; 0; 0 0; 0; 0; 1 2 4 3 0; 0; 0; 4 0; 0; 0; 3 4 1 4 0; 0; 0; 0 3 4 3 0; 0 0 0; 3 2 0 3 0; 4 2 0; 3 4 0; 0; 0;

108E 249 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0 3 0 0 0; 0 0; 0 0 0 0 0 0; 4 0; 0 0 0 3 4 4 0; 0 0; 0 4 4 4 3 0 3 0 0 4 0 3 2 0

65E 176 0 0; 0; 0 0 0 0 0; 0 0 0; 0 0 2 2 0; 4 0 2 0; 0 0 0 0 0 0 2 4 0; 0; 0; 0 3 4 3 0; 0; 0 0; 1 0; 0 3 0 3 0 0 3 0 0; 2 0;

2E 16 0 0 0 0 0; 0 0 0 0 0; 0; 0 0 0 0; 0; 0 0 0; 2 0 0 0; 0 0 0 1 4 0; 0; 0; 0 3 4 0 2 0 2 3 0; 3 2 0 3 4 0 3 0 1 0; 0;

35E 150 0 0 0; 0; 0 0 0 0 0 0 0 0 0 2 3 0 0 0; 3 4 0 0 0 0 0 0 0; 4 0; 0 0; 0 4 4 0 4 0 0; 3 3 3 4 4 4 0 0 4 0 4 4 4

2E 24 0 0; 0; 0 0 0; 0; 0; 0; 0; 0; 0 0 0; 2 0; 0; 3 2 0 0 0 0 0; 3 0 2 4 0; 0; 0; 0; 3 4 4 3 0 0; 3 0; 3 3 0 4 3 0 3 0 1 2 0;

99E 20 0 0 0 0 0 0 0 0 0 0 0; 0 0 0; 3 0; 0 0 0; 0 0 0 0; 0 2 0 1 4 0; 0; 0; 0 3 4 3 4 0; 0; 2 0; 4 2 0 4 0 0 3 0 3 1 0

3E 22 0 0 0; 0 0; 0 0 0 0; 0; 0; 0 0; 0; 0; 1 0 3 2 0 0 0 0, 0 0 0; 2 4 0; 0; 0; 0 1 4 0 4 0; 0; 3 2 2 0; 3 0 4 4 0 3 0 3 3 0;

12E 89 0 0 0 0 0 0 0 0 0; 0 0 0 0; 0 0 0; 0; 0 0; 0 0; 0 3 0 0 0 0; 4 0; 0 0; 0 4 4 4 0; 0; 0 2 0 0; 0 0 0; 0; 0; 0; 0; 3 4 0

99E 16 0 0 0 0 0 0 0 0 0 0 0; 0 0 0; 0; 0 0 0 1 0 0; 0 0; 2 3 0 1 4 0; 0 0; 0 3 0 0 0 0 0; 3 1 4 3 0 3 0 0 3 0 1 1 0;

171E 191 4 4 4 4 4 4 4 4 4 3 2 3 3 1 4 4 3 4 3 4 4 4 4 4 3 4 3 4 0; 0 0 0; 3 3 4 4 0; 4 2 4 1 4 4 4 3 4 4 4 4 4 3 4

102E 25 0 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 0; 3 3 3 3 0 3 0; 3 0; 0; 3 0 3 3 4 0; 0; 0; 0; 3 4 1 3 2 4 0; 4 3 4 3 0; 3 3 4 3 3 3 2 0;

195E 220 4 4 4 4 4 4 4 4 3 4 4 0; 4 4 4 4 0; 0; 0; 0; 4 4 3 4 4 1 0; 4 0; 0; 0; 0; 4 4 4 2 0; 4 4 4 0; 4 4 4 4 0; 3 4 4 4 1 4

Postulation of Seedlings Resistance Genes to Yellow Rust in Commercial Wheat Cultivars from Yunnan Province in China 1727

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these cultivars carried Yr8, and other gene(s). According to same method, we knew Yunxuan 3 and 06D6-6 carried Yr6 and other gene(s). Yunmai 54 and 017-10 carried Yr17 and other gene(s). R101 carried Yr2+YrA and other gene(s). Wenmai 12 carried Yr7 and other gene(s). Linmai 15 carried Yr27 and other gene(s). Except Kunmai 4 and Yunmai 56, there were 19 cultivars whose spectrum were different to any of differential cultivars, so we could not characterized what gene they carried. They were Yunmai 43, Yunmai 47, Yunmai 51, Yunmai 57, Yunxuan11-12, Kun 022-222-1, Fengmai 35, Fengmai 36, Feng03-2, Feng 1124, Jingmai 14, Demai 3, Demai 7, Chumai 12, Yimai 2003-27, Wenmai 11, 02D2-282, 91E001, and R101. Another cultivar Yunmai 101 had no data on 7 isolates, so we could not well and truly characterize which gene(s) it carried. Yunmai 42 was susceptible to all test isolates, so it had no test known resistance gene.

DISCUSSION Suggestion on deployment of wheat cultivars in Yunnan Province The results indicated that the resistance gene to yellow rust is not abundance and balance in Yunnan cultivars. Only Yr9 has very high frequency, the other gene is lower frequency. Some genes are only present in single cultivars. Many genes could not be characterized. We can not provide a perfect gene deployment scheme because the cultivars we analyzed is limited, and characterized gene is also limited in this study. But the research results will guide on cultivars rational use and provide information for gene deployment scheme in the future. Environment is very complex in Yunnan Province. There are 5 yellow rust prevalence regions in it, which are Center of Yunnan altiplano basin, West Yunnan hill basin, Northwest Yunnan alp gorge, Southwest Yunnan hill dale, and Northeast Yunnan Mountain. The pathogen can live through winter and summer in these regions. But the epidemic time and rule of yellow rust is different. We suggest the different Yr genes in dif-

LI Ming-ju et al.

ferent epidemic regions were planted to cut off the intercommunication of the virulence gene and achieve gene diversity deployment and gene segregation. Thus we can avoid rust breakout and delay the resistance life of cultivars. Yunnan is comparatively independent and special in Chinese wheat yellow rust epidemic system. It is deduced that Yunnan is the probable original pathogen base of wheat yellow rust in China. So Yr gene in Yunnan should be different from other rust epidemic regions. The intercommunion of pathogen virulence gene can be cut off to realize the headstream management and the spread route.

About Yr9 genes Yr9 is a major gene to yellow rust in the wheat cultivars for test. It is postulated to be present in 13 cultivars. Yr9 was from IB/IR wheat-rye chromosome translocation lines (Zeller 1973; Wang et al. 1994; Niu et al. 2000), present in cultivars such as Neuzucht, Kavkaz, Predgornaja from Russia and Lovrin10, Lovrin 13 from Romania (Wang et al. 1994; Niu et al. 2000). It has been taken efficacy in many areas over the world (Rajaram et al. 1983), had been introduced in China in the 1970s because of its excellent agriculture character and resistance to wheat rust and powdery mildew, and has been widely used as parent materials by breeding scientists. So it caused many commercial cultivars with Yr9 in China (Wang et al. 1994; Niu et al. 2000; Chen et al. 2009). Yunnan is a region where wheat yellow rust and powdery mildew often break out. Wheat yellow rust had broken out for 4 times during the 1970s to 1980s (Li 2004). There are so many commercial cultivars carring Yr9 that scientists used those resistance resources as breeding parent materials. The result is accordance with the former scientists (Wang et al. 1994; Niu et al. 2000). We suggest to screen some high quality of cultivars from which carring Yr9 in consideration of agriculture character to reduce the amount of Yr9 cultivars, avoiding it is planted in a large area at the same place in the meantime, and with other gene cultivars in order to realize gene diversity deployment and delay the resistance life of cultivars.

© 2011, CAAS. All rights reserved. Published by Elsevier Ltd.

Postulation of Seedlings Resistance Genes to Yellow Rust in Commercial Wheat Cultivars from Yunnan Province in China

About other gene cultivars Yunmai 52 and Mian 1971-98 carry Yr26, Kunmai 4 and Yunmai 56 carry unknown effective gene(s). The four cultivars are effective resistance resources and can be popularized mainly in Yunnan at present. Yr21 gene is the same situation as Yr9 gene. Cultivars carried other single gene(s), could be planted with Yr9, Yr21 or Yunmai 52, Mian 1971-98, Kunmai 4, and Yunmai 56, etc. Introducing effective resistance genes such as Yr5, Yr10, Yr11, Yr12, Yr13, Yr14, Yr15, Yr16, Yr17, Yr18, Yr26, Yr27, YrSpp, YrGaby, and Zhong 4 translocation lines are urgent at present. Yunmai 42 susceptible to all test isolates carried no test Yr gene. Yunmai 42 has 1.7×104 ha acreage and hold 5.4% of all wheat acreage by the statistics of Yunnan seed management station in 2010. It is the second large acreage of all commercial cultivars (internal data). Maybe the acreage of Yunmai 42 is much larger than the number because some was not taken statistics. So the plant acreage of high susceptible cultivar should be deduced to avoid the outbreak of yellow rust. There were 22 cultivars which can not be characterized their resistance genes. We have known that parents of breeding are wheat landrace in Yunnan and resistance materials from CIMMYT besides main resistance resources in China. These parents gene information are unknown special in landrace. So introduced gene information can not be traced. The cultivars with unknown gene(s) should be further studied so as to be utilized in the wheat breeding program well.

The accuracy of gene postulation Postulation of resistance gene is a fast and simple method of all gene analysis. It can get much genetic information about host and pathogen in a short time. But the accuracy is restricted by known gene cultivars and test isolates. In general, single gene line or near-isogenic lines (NILs) is good choice. But for cultivars carried multigene or gene combination, NILs could not exactly characterize its gene(s), known gene cultivars with multigene or gene combination can recognize effectively. We can know this by seeing Avocet S*6/ Yr7 (Yr7) and Lee (Yr7, Yr22, Yr23), Avocet S*6/Yr8 (Yr8) and Compair (Yr8, Yr19), Avocet S*6/Yr9 (Yr9)

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and Clement (Yr9, YrCle) in Table 1. The innovation of this study was to use 7 NILs from Australia, which are Avocet S*6/Yr5, Avocet S*6/Yr6, Avocet S*6/Yr7, Avocet S*6/Yr8, Avocet S*6/Yr9, Avocet S*6/Yr10, Avocet S*6/Yr15, and plus some representative known gene cultivars as differential hosts, enriching the genes information and making the postulation more perfect and accurate. Nowadays, there are 2 set of NILs differential host in the world, one bred by Australia and the other by IPPCAAS. The results of test indicated that Australian NILs is not adequately suitable for China. China has bred 8 NILs successfully, which were Taichung 29*6/Yr1, Taichung 29*6/Yr2, Taichung 29*6/ Yr5, Taichung 29*6/Yr7, Taichung 29*6/Yr9, Taichung 29*6/Yr10, Taichung 29*6/YrSpP, and Taichung 29*6/ YrKy2 (Xu et al. 2004). These NILs are being tested its effectiveness nowadays, and it will be used for the genetic analysis of either host or pathogen in the coming days. In addition, the more diversity of avirulence/virulence isolates was selected, the better identification is obtained. In China, many researchers, such as Wang et al. (1994) and Niu et al. (2000), have postulated resistance genes to yellow rust. The former used 20 isolates for postulation, and the later used 26 isolates. It included some Chinese dominance races and representative isolates over the world and its virulence spectrum is diversity and has a good identification effect. Based on the former research, in this study, we adjusted the isolates according to the virulence and joined Chinese new prevalent races 195E220 (CYR33) to make the postulation more accurate and perfect. That is to say, our innovation is the improvement on test isolates and differential hosts, and postulated commercial wheat cultivars from Yunnan the first time. In spite of this, none of the isolates can infect Yr5, Yr10, YrMor, Yr15, and Yr26 in this study, so we can not differentiate these 5 genes. It indicated that isolates should be adjusted constantly to meet the research need, and also indicated Yr5, Yr10, YrMor, Yr15, and Yr26 genes are effective genes in the meantime nowadays. Yellow rust pathogen is sensitive to environment and host background. It displayed that ITs could be changeable under different conditions or different genetic backgrounds though the cultivars probably carried same gene (s).

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So gene postulation is very complex. To make postulation accurate it is necessary to develop a set of known gene cultivars as differential hosts suitable to China and consider pedigree of test cultivars. Moreover, molecular marker, allele hybrid, gene linkage, or monosomic analysis can be used as an assistant.

CONCLUSION We have known the present of Yr gene of commercial wheat cultivars from Yunnan in this study. There are 10 named Yr resistance genes were characterized from 52 test cultivars. In which, Yr9 had the highest frequency, was present in 13 cultivars; Yr21, the 2nd, was present in 4 cultivars; Yr8, the 3rd, was present in 3 cultivars; Yr6, Yr17 and Yr26, the 4th, were present in 2 cultivars, respectively. The other genes, such as, Yr2+YrA, Yr7 and Yr27, were only present in single cultivar, unknown gene(s) or gene(s) combination(s) were present in 22 cultivars. One cultivar (Yunmai 42) had no resistance gene tested in this study. Yunmai 52, Mian 1971-98, Kunmai 4, and Yunmai 56 were considered as effective resistance resource and should be popularized mainly. Cultivars carrying Yr9 should be restricted to use alone in wheat production, and be planted match with other genes. Yr21 is the same situation. It is urgent to introduce effective resistance genes such as Yr5, Yr10, Yr11, Yr12, Yr13, Yr14, Yr15, Yr16, Yr17, Yr18, Yr26, Yr27, YrSpp, YrGaby, and Zhong 4 translocation lines in wheat breeding program to realize gene diversity for controlling of yellow rust. The predominant cultivar Yunmai 42 should be cut down the acreage to avoid the breakout of yellow rust in Yunnan Province. The cultivars with unknown gene(s) could be further studied so as to utilize in the wheat breeding program well.

Acknowledgements The financial support by the Ministry of Science and Technology, China (2011CB100403), the Ministry of Agriculture, China (200903035), and the Special Project from State Key Laboratory for Biology of Plant Diseases and Insect Pests, Chinese Academy of Agricltural

LI Ming-ju et al.

Sciences (SKL2009OP09) are gratefully acknowledged. The authors are grateful to various cooperators for supplying cultivars and pedigrees.

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