Barberry plays an important role in natural infection of stripe rust on wheat in China

Zhensheng KangState Key Laboratory of Crop Stress Biology for Arid Areas,

Northwest A & F University, Yangling, Shaanxi, China

Diseased area: between 3-6 million ha. Yield losses: 10-50%.

Years Losses

(million tonnes)

1950 6.0

1964 3.2

1990 2.6

2002 1.4

Wheat stripe rust is a destructive disease throughout all winter wheat regions and is considered the most important disease of wheat in China.

Virulence variation for rusts maybe due to sexual hybridizationmutations somatic hybridization

However, the mechanism of sexual hybridization for Pst has been neglected since the sexual stage was presumed to be absent.

Resistant wheat

cultivars

Rust virulence variation

Huge yield losses

In 2010, some Berberis spp. were shown to serve as alternate hosts for the wheat stripe rust pathogen. B. chinensis, B. holstii, B. koreana B. vulgaris.

Jin et al. Phytopathology, 2010

Question: Does the sexual stage of wheat stripe rust occur under natural conditions, particularly in China?

Field Surveys for Berberis spp. Susceptible test of Berberis to stripe rust Isolation of stripe rust from nature-infected

Berberis Virulence test for recovered isolates Mock-inoculation on Berberis in fields

Surveys for Berberis spp.in China

215 of the ~500 described Berberis spp. in the world are endemic to China;

Many of China's Berberis spp. distribute in the western over-summering areas (hot-spot).

Western China: Sichuan ： 81; Chongqin ： 30; Yunnan ： 78; Tibet: 55; Guansu ： 26; Shaanxi: 20; Guizhou ： 19; Qinghai ： 13; Xinjiang ： 5; Ningxia ： 3;

Central China: Hubei ： 24; Henan ： 7; Shanxi ： 10; Hunan ： 9; Anhui ： 2; Eastern China: Hebei ： 6; Jiangxi ： 5; Guandong ： 4; Guanxi ： 4; Hujian ： 5;

Distribution of Berberis species in different regions of China

Surveys for Berberis spp.in China

No barberry plant Barberry plants distributedBarberry plants with rusts

35 barberry species were surveyed and identified.

Over-summering area

Are these Berberis spp. susceptible to wheat stripe rust ?

Identification of Berberis spp. as alternate hosts of wheat stripe rust in green house

Dew chamber

We collected seeds and seedlings of Berberis spp. from the fields and inoculated using telia of Pst in the greenhouse.

Normally, we see pycnia on the leaves of susceptible Berberis spp. 10-13 days after inoculation.

Infection of basidiospore and development of pycnia

Pycnia on Berberis

Identification of Berberis spp. as alternate hosts of wheat stripe rust in green house

About 20 days after inoculation, we see aecia develop on the leaves. Aeciospores can infect wheat through the stoma and produce typical rust symptoms (uredinia).

Identification of Berberis spp. as alternate hosts of wheat stripe rust in green house

23 Berberis species: alternate host for Pst Successful production of pycnia, and aecia on upper and back sides of barberry leaf after inoculation

Zhao, J., et al. Phytopathology, 2013, 103(9):927-934

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G H I J K L

M N O P Q R

Zhao, J., et al. Phytopathology, 2013, 103(9):927-934

No. Berberis spp. Orgin Distribution1 B. aggregata Gansu, China Gansu, Sichuan, Hubei, Qinghai, Shanxi 2 B. brachypoda Gansu, China Gansu, Sichuan, Hubei, Qinghai, Shanxi,Henan, Shanxi3 B. potaninii Gansu, China Gansu, Shaanxi, Sichuan4 B. soulieana Gansu, China Gansu, Shaanxi, Sichuan,Hubei5 B. dasystachya Shaanxi, China Gansu, Shaanxi,Hubei,Shanxi6 B. shensiana Shaanxi, China Shaanxi,Gansu7 B. atrocarpa Sichuan, China Sichuan, Yunnan, Hunan8 B． ferdinandi-coburgii Yunnan, China Yunnan9 B. phanera Yunnan, China Yunna, Sichuan10 B. aggregate var. integrifolia Yunnan, China Gansu, Sichuan,Qinghai,Hubei,Shanxi11 B. davidii Yunnan, China Yunnan12 B. stenostachya Gansu, China Gansu, Shaanxi, Shanxi13 B. wangii Yunnan, China Yunnan14 B. circumserrata Shaanxi, China Shaanxi, Hubei, Gansu, Qinghai,Henan 15 B. poiretii Beijing, China Shaanxi, Qinghai, shanxi, Hebei, Jilin, Liaoning, 16 B. guizhouensis Guizhou, China Guizhou17 B. wilsonae Yunnan, China Yunnan, Tibet, Shaanxi, Qinghai, Hubei, Guizhou18 B. sp. (unidentified) Tibet, China Tibet19 B. jamesiana Yunnan, China Yunnan， Qinghai, Chongqing, Tibet, Sichuan20 B. coryi Yunnan, China Yunnan21 B. wilsonae Yunnan, China Yunnan, Sichuan, Tibet, Gansu22 B. sp. Tibet, China Tibet23 B. sp. Tibet, China Tibet

Species of barberry identified as alternate hosts for Pst by artificial inoculation using germinated teliospores in China

Some species are evergreen, distributed in southwest regions. Others are deciduous, distributed in northwest regions. Some susceptible species (e.g., Berberis soulieana, B. brachypoda, and B. shensiana) are widely distributed in the western over- summering areas.

Berberis soulieana

B. shensiana

Can barberry species be infected by the stripe rust fungus (Pst) in nature?

It is very common to see pycnia and aecia on infected Berberis leaves in fields in May.

Obtaining of Pst isolates from rust-infected barberry growing in nature

20 Pst isolates recovered from the infected barberry 4 Pst isolated from 3 barberry species in 2011 16 Pst isolates from 3 barberry species in 2013

collected the infected Berberis leaves

Single aecium (SA) was used for inoculation

Recovered SA isolateon wheat leaf

Berberis spp. No. of aeciaNo. of isolate Rate (%)

IT0 IT1-2 Pst Pgt Pst Pgt

B. brachypoda 1519 479 1032 2 6 0.13 0.39

B. shensiana 410 35 374 1 0 0.24 0.00

B. soulieana 384 367 16 1 0 0.26 0.00

B. potaninii 742 711 28 0 3 0.00 0.40

B. aggregata 648 633 13 0 2 0.00 0.31

Total 3703 2225 1463 4 11 0.11 0.30

Pst isolates recovered from rust-infected Berberis spp. in Gansu, and Shaanxi in 2011

*I T0 indicates no any necrosis, or/ and chlorosis on wheat after inoculation, I T1- 2 indicates necrosis, or/ and chlorosis; Pst =Puccinia st r iif ormis f . sp. t r it ici; Pgt =Puccinia graminis f . sp. t r it ici

Comparison of infection types on Chinese differential hosts of eight major races of Pst and the four Pst

isolates recovered from three barberry species in 2011

Virulence tests demonstrated that the infection types of the four barberry-recovered cultures are different compared to the major Chinese races.

Cultures and

racesOrigin of cultures

Differential hosts

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

B2011-1 Berberis brachypoda A V A V V V A V A VA V A A V A A A A A

B2011-2 B. brachypoda A V A V V A A V A A V A A A A A A A A

B2011-3 B. shensiana A V A V V A V V A AV V A A AV A A A A A

B2011-4 B. soulieana A V A A V V A V A A A A A V A V A A A

CYA33 Triticum aestivum V V V V V V V V V V V V V V A V A A A

CYA32 T. aestivum V V V V V V V V V V V V V V A V V A A

CYA31 T. aestivum V V V V V V V V V A V V A V A V V A A

CYA30 T. aestivum V V V V V V V V V A V V A A A V V A A

CYA29 T. aestivum V V V V V V V V V A V V A A A V A A A

CYA28 T. aestivum V V V V V V V V V A V A A A A V A A A

CYA23 T. aestivum V V V V A V V V V A V A A A A A A A A

CYA17 T. aestivum VA V A VA A VA V A A A AV A A A A A A A A

Zhao, J., et al. Phytopathology, 2013

Berberis spp. No. of aeciaNumber of isolate* Rate (%)

IT 0 IT 1-2 Pst Pgt Pst Pgt

B. shensiana 3677 3630 40 4 3 0.11 0.08

B. brachypoda 4477 4406 59 8 4 0.17 0.15

B. sp. (Tibet) 1163 1150 6 4 3 0.34 0.26

Total 9317 9174 105 16 12 0.17 0.13

*I T 0 indicates no any necrosis, or/ and chlorosis on wheat after inoculation, I T1- 2 indicates necrosis, or/ and chlorosis; Pst =Puccinia st r iif ormis f . sp. t r it ici; Pgt =Puccinia graminis f . sp. t r it ici

Pst isolates obtained from the infected Berberis spp. in Shaanxi, Gansu and Tibet in 2013

Berberis(origin)

Isolate No.

Chinese differential hosts for Pst

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1920(ck)

Race /race group

　 U1 AV

V V V V V V V A V V A V VA A AV A A A V SuG

　 U2 A V V V V V V V A V AV

A A V A A A A A V SuG

　　B.aggregata

(Gansu)　

U3 A V A AV V V V V A V AV

A A V A A A A A V SuG

U4 AV

A V V AV

V V V A V V V A V A V A A A V SuG

U5 V V V V V V V V V V V V V V A V V A A V CYR32

U6 A V AV

V V V V V A V V V A V A A A A A V SuG

　 U7 V V V V V V V V A V V AV

A V A A A A A V SuG

　 U8 V V V V V V V V V V V V V V A V V A A V CYR32

B.shensiana (Shaanxi)

　　　

U 9 V V V V V V V V V V V V V V A V V A A V CYR32

U10 V V V V V V V V V V V V V V V V A A A V SuG

U11 A V A V V V V V A AV

AV

A A V A A A A A V SuG

U12 A V A AV V V V V A V AV

A A V A A A A A V SuG

B.sp. 　　（ Tibet)

U13 AV

V V V A V V V A V V A A V A A A A A V SuG

U14 A V V V V V VA

V A V V A A V A A A A A V SuG

U15 AV

V V AV A V V A A V A A V V A A A A A V SuG

U16 A V A AV A V V V A A AV

A A V A A A A A V SuG

3 recovered isolates were identified as race CYR 32. Other 13 isolates have different virulence patterns as compared

to the major Chinese races , and can be considered as new races.

Chinese differential hosts for Pst

A=avirulent ; V=virulent; AV/VA =segeration of resistant and susceptible; ck=Mingxian 169 susceptible to Pst.SuG=race group virulence for Suwon 11(YrSu); HyG=race group virulence for Hyrbrid 46 (Yr3b,Yr4b)

CYR= chinese yellow rust

Virulence patterns of 16 recovered isolates on Chinese differential host sets in 2013

Single Aecia from barberry

Recovered isolate from single aecium

Single uredium (Su) isolates

Virulence test on NILs

Does the sexual reproduction under natural conditions contribute to virulence variation for Pst ?

• 120 single-uredium (SU) isolates were make from 16 recovered

isolates from infected barberry.• Virulence test for each SU isolates on near-isogenic lines. • Remarkable variation in virulence patterns among the SU isolates.

Virulence patterns of single-uredium isolates from recovered Pst isolate on near-isogenic lines

SU isolate

Yr NILs

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Yr2 Yr5 Yr6 Yr7 Yr8 Yr9 Yr10 Yr15 Yr17 Yr24 Yr26 Yr27 Yr44 YrSp YrTr1 YrExp2 Yr25 Yr28 CK

U10* VA A V A A A A A A A AV A V A A A V V VU10-1 A A V A A V A A A A A A V A A A V V VU10-2 A A V A A A A A A A A A V A A A V V VU10-3 A A V A A A A A A A A A V A A A V V VU10-4 A A V A A V A A A A A A V V A A V V VU10-5 A A V A A V A A V A A A V V A A V V VU10-6 V A V AV A A A A V A A A V V A A V V V U10-7 A A V A A V A A V A A V V V A A V V VU10-8 A A V A A V A A A A A A V A A A V V VU10-9 A A V AV A V A A A A A A V A A A V V V

• SU isolates U10-2 and U10-3 share the same virulence patterns,

• Other 7 SU isolates have different virulence patterns.

*U10 isolate recovered from Berberis shensiana in Shaanxi

SU isolate

Yr NILs1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

Yr2 Yr5 Yr6 Yr7 Yr8 Yr9 Yr10 Yr15 Yr17 Yr24 Yr26 Yr27 Yr44 YrSp YrTr1 YrExp2 Yr25 Yr28 CK

U2* A A A AV V A A A A A V A A A A V A A VU2-1 A A A AV V A A A A A V A A A A V A A VU2-2 A A A A V A A A AV A V A V A A V A A VU2-3 A A VA AV V A A A A A V A A A A A A A VU2-4 A A A A V A A A V A V A V A A V A A VU2-5 A A AV A V A A A A A V A A A A V A V VU2-6 A/V A V V V A A A A A V A V A A V A A VU2-7 A A A A V A A A A A V A A A A V A A V

U2-8 VA A V A/VA

V A A A V A V A VA A A V A A V

U2-9 A A AV A V A A A A A V A V A A V A A VU2-10 A A A A V A A A A A V A A A A V A A VU2-11 A A AV VA V A A A A A V A A A A V A A VU2-12 A A AV A V A A A A A V A A A A V A A V

U2-13 A/VA

A A/V A V A A A V A V A A A A V A A V

U2-14 A/V A A/V A/VA

V A A A A A V A A/V A A V V VA V

“/” indicates various infection type on first and second leaf of genotype wheat cultivar. AV, VA= segregation of resistant and susceptible.*U2 isolate recovered form Berberis aggregata in Gansu.

• U2-7 and U2-10, share the same virulence patterns,

• Other 12 SU isolates have different virulence patterns.

Virulence patterns of single-uredium isolates from recovered Pst isolate on near-isogenic lines

Single Aecia from barberry

Recovered isolate from single aecium

Single uredium (Su) isolates

Virulence test on NILs

Does the sexual reproduction under natural conditions contribute to virulence variation for Pst?

• The single-uredium isolates originally from aecia on naturally

infected barberry plants consisted of diverse of virulence

patterns, which should be due to sexual reproduction on the

barberry plants.

Does infection of stripe rust on Barberry cause the disease in adjacent wheat?

Does infection of stripe rust on Barberry cause the disease in adjacent wheat?

Mock infection were performed in Gansu, China, by putting wheat tissues bearing telia on the top of barberry plants in Middle of April, 2013.

The inoculated barberry plants showed symptom in early May, 2013, and 70 Pst isolates were obtained from mock-inoculated barberry.

Stripe rust appeared on wheat adjacent to the mock-inoculated barberry plants before the end of May, 2013.

No stripe rust on wheat in the same field far off mock-inoculated barberry plants, and in other fields at this time.

70 Pst isolates were obtained from nearby wheat.

Does infection of stripe rust on Barberry cause the disease in adjacent wheat?

Comparison of pathotypes on Chinese differential hosts for Pst isolates from mock-inoculated barberry and

from nearby wheat

Origin Number of race

Race type CYR32 CYR31 Guinong 22 Hy46-7 Other racesa

Mock-inoculated barberry

70 11 1 20 1 37

Nearby wheat 70 8 0 19 8 35a Infection type of other races were not matched with those of known Pst races.

The results showed that the races derived from mock-inoculated barberry matched with those isolated from nearby wheat.

23 of the 30 tested barberry species show susceptibility to Pst, indicating that there is a great diversity of potential alternate hosts for Pst in China.

20 Pst isolates obtained from different barberry species in the fields indicated that the sexual stage of Pst occurs under natural conditions.

Virulence tests for single-uredium isolates recovered from a single aecium demonstrate that the sexual reproduction contributes to virulence variation for Pst.

Summary

Pst must now be considered a macrocyclic fungal pathogen.

The earmarked fund for Modern Agro-industry Technology Research System in China

National Basic Research Program of China (973)

Nature Science Foundation of China

The 111 Project from the Chinese Ministry of Education

AcknowledgementDr. Jie Zhao Prof. Lili Huang Dr. Hongchang Zhang Dr. Gangming Zhan Dr. Qingmei Han Dr. Yonghong ZhangDr. Dejun Han Dr. Xiaojie WangDr. Jun Guo Dr. Xueling Huang Dr. Wenming zheng Mrs. Guorong Wei All PhD and Master students in My Lab.

Dr. X M. Chen, Dr. H. Buchenauer, Dr. Robert McIntosh , Dr. Colin Wellings, Dr. Scot H. Hulbert, Dr. Jin-Rong Xu, Dr. Shiping Wang, Dr. Hei Leung, Dr. J. ChongDr. Yue Jin, Dr. Ravi Singh, Dr. Zacharias Pretorius

Thanks for your attention!