Good morning, my name is Iago Hale, from the University of New Hampshire in the United States, and it is my great honor to moderate this morning’s panel discussion: The barberry connection: Looking for the source of pathogen variability in stem and stripe rusts. Thank you all for being here, and thank you especially to our hosts for this opportunity. (Thank you for this opportunity to present and discuss this important topic.)
This morning, we would like to shift perspective a bit and focus our attention on what the stem and stripe rust pathogens are doing when they are not living on cereal hosts. To aid everyone in the shift in perspective, I’d like to show a short video on the life cycle of wheat stem rust, recently produced as an educational piece for the BGRI.
Just as our interest in breeding for resistance to the rusts is not new, our interest in the alternate host is not new either. But while efforts to discover and deploy new resistance genes have made great strides since the discovery of Ug99, rekindled interest in the alternate host has lagged behind. From a crisis management perspective, this is understandable; but in terms of looking ahead and working toward an increased durability of resistance to the wheat rusts, history suggests that we may benefit from trying to control the emergence of new virulent races in the first place, in addition to breeding for enhanced resistance.
Though the connection was not formally made until 1865, with the work of de Bary, the negative impact of barberries growing in proximity to wheat fields had been recognized for hundreds of years, as evidenced by the existence of barberry eradication laws as far back as the 1600’s in France. The 17 and 1800’s saw similar laws enacted in the New World and across Europe.
In the United States, following devastating epidemics in 1904 and 1916, a nearly 60-year barberry eradication program was carried out. During this program, an enormous amount of resources was invested not only in direct eradication efforts but also in educating the public, more generally, about the threat posed by barberries in wheat-producing regions.
In a paper summarizing the US eradication work in the 20th century, in which over 100 million bushes were destroyed throughout the north central plains, Dr. Alan Roelfs concluded that barberry eradication led to four measurable results. The first two relate to the fact that barberry can harbor local, early sources of inoculum. The second two relate to the fact that barberry provides a mechanism for increasing the diversity of the pathogen population. By both decreasing the quantity of early season inoculum (and therefore the likelihood of virulent mutations) stabilizing the pathogen’s races, barberry eradication led to measurable increases in the durability of deployed resistance genes, an important contributing factor to the decades of stem rust control now threatened by the emergence of the Ug99 race group.
With a lesson like this in mind, and knowing now that barberry can also serve as an alternate host to stripe rust, it is interesting to step back and take a more global perspective. Many of the known hot spots for novel race emergence, for both stem and stripe rust, such as East Africa, central and western Asia, southwestern China, and the Pacific NW of North America, are also areas for which there is no history of systematic surveillance or control of the alternate host.Given the highly diverse group of endemic barberry species found on every continent, except Australia, and given the rapid emergence of novel races of these historic pathogens from certain regions, several basic research questions present themselves.
First of all, what is the distribution of alternate hosts, relative to wheat production, around the world? And what role do these populations play, if any, in the emergence of new virulent races?We are very fortunate today to have with us a panel of seven scientists from around the world, whose research is at the forefront of answering these questions. While there were a few talks which touched on the alternate host during the previous meeting over the past few days, now we have an opportunity to really focus on this topic, and this essential question: Do alternate hosts undermine our efforts to achieve durable resistance?As a general structure to the presentations this morning, we’ll begin with Drs. Wanyera, Getaneh, and Skolotneva discussing their survey work on barberry, as it relates to wheat stem rust in their regions. Then Drs. Berlin and Kang will widen the discussion to other Puccinia species, including wheat stripe rust. Dr. Nazari will then discuss the potential role of barberry in central and western Asia, the center of diversity of the genus. And finally, Dr. Yue Jin will wrap up with a discussion of our current gaps in knowledge.After the panelists present, we will hopefully have 15-20 minutes remaining for questions and discussion. And with that, I would like to give the floor to Dr. Wanyera, from the Kenya Agricultural Research institute in Njoro.
Common ancestrySamples connected between barberry and grass hostsSeems to be a reproductive barrier, Johnson in the 40’sThis differences are also reflected in aecial morphology
The question: what is the virulence spectra?
The two questions are two sides of the same coin, one version for the pathologists and one for the breeders.
As Dr. Hodson said yesterday, Ug99 was a catalyst, a new virulent race that made us realize how complacent we had become to the threat of the wheat rusts in the latter half of the 20th century. Since its formal inception 7 years ago, the GRI, now the Borlaug Global Rust initiative has made tremendous progress toward its stated objectives, in terms of research, capacity building, and deployment of resistance, preparing nations for the arrival of Ug99 and its variants.As these races march onward to ever wider geographical reach, we look ahead to the next leap in virulence. How do we prepare for it?
As our panelists outlined for you this morning, there is reason to think that one prong in our strategy for achieving increased durability of resistance should entail a greater understanding of the role of the alternate host in wheat-growing regions around the world, particularly in historic hot-spots of novel race emergence. Though work on the alternate host has lagged somewhat, compared to work on the primary host, progress has been made in recent years.The discovery of new species of alternate hosts, the discovery of natural, sexual populations of stem rust in Africa and North America and stripe rust in Asia, direct evidence that the sexual stage on barberry can lead to increased variation in virulence of both stem and stripe rust. History has taught us to not be complacent with breeding for rust resistance. History has also taught us that we should not be complacent with regard to the alternate host, a message that gains even greater significance in light of the rebounding populations of common barberry in North America and Europe.
Much has been accomplished, but much work remains to be done, which is the reason we have recently produced a barberry surveillance training video, now available through the BGRI website, as well as on the CD in your conference registration packet. About 20 minutes long, this video provides some background regarding barberries and then demonstrates a method for isolating cereal rust species from infected barberry leaves. This training video dovetails with the BGRI’s earlier video on race identification and, we hope, will expand the scope of work of the rust research community.
And with that, I would like to thank our panelists, invite them to the stage, and open the floor for questions.
The Barberry Connection:Looking for the source of pathogenvariability in stem and stripe rustsPanel discussion, BGRI Technical WorkshopMonday, September 3, 2012 (9:00-10:30 AM)
Barberry eradication laws 1600’s Ronen, France 1726-1766 New England colonies CT, MA, RI 1800’s Many European countries Denmark, England, France, Germany, etc.Stakman EC (1918) “The Black Stem Rust and the Barberry.” Yearbook of USDA – 1918, pages 75-100.
>100,000,000 barberry bushes destroyed 1. Delayed onset of disease 2. Reduced virulent inoculum in the spring 3. Decreased number of pathogenic races 4. Stabilized pathogenic races (e.g. QCC) Durability of deployed genetic resistanceRoelfs AP (1982) Plant Disease 66:177-181
Known global hot-spots for the recent emergence of new races: Areas without a history of systematic alternate host surveillance and control Endemic barberries are found on every continent, except AustraliaNearly 500 barberry species, with high diversity in South America, Africa, and Asia
1. What is the distribution of alternate hosts, relative to wheat production? 2. What role, if any, do these species play in rust epidemiology today? A. Berlin, Sweden E. Skolotneva, Russian Fed. Y. Jin, USA K. Nazari, ICARDA ZS Kang, PR China W. Getaneh, Ethiopia R. Wanyera, Kenya Do alternate hosts undermine our efforts to achieve durable resistance?
THE BARBERRY STORY IN KENYA Ruth WanyeraKenya Agricultural Research Institute (KARI), Njoro Email:firstname.lastname@example.org
UG99 PRESENT STATUS The rapid emergence of Ug99 derivative races (a "stacking" of virulences first Sr31, then Sr24, then Sr36, etc.) suggests that sexual recombination may play a role in the evolution of Pgt virulence in East Africa TTKSF
1. Are there barberries in East Africa?2. Are they susceptible to cereal rusts?3. Do they function as alternate hosts under natural conditions? LLL Life cycle of stem rust
Records at the Kenya National museumshowed the presence of Berberis holstiiEngl., in East Africa
Barberry hunting and aecia collection since 2008
Barberry hunting… Njoro Area Mau-Narok Mt. Kenya Olkalau/Nyahururu Narok Meru (Chogoria Forest) Mt. Elgon (Kenya Side) Barberry surveyed sites• Aecia positively identified in the lab
The barberry plant ismedicinal, fruits areeaten by children Dug up barberry bushLocating barberry standsrequired coordination ofthe local communitiesand experts outside thewheat rust community
InoculationsInoculation process initiated in thegreenhouse at Njoro to determine if theaeciospores produced on the barberryleaves are wheat rusts, provedunsuccessful (environmental conditions?).KARI Muguga South (away from wheatgrowing areas and barberry sites), but nosporulation was observed ( unfavorableconditions?)
Inoculations Efforts made trying to get aeciospores from Kenya to the CDL for analysis, proved unsuccessful because of viability issues
Way forward Need resources to conduct molecular diagnostics locally In country capacity building to isolate and identify Pgt from alternate hosts, due to fragility of aeciospores relative to urediniospores
Aecial Infections on Barberry Plants (Zinkila) in Ethiopia W. Getaneh, EIAR - Ambo Beijing, China September 2012
Introduction• Around 1958, barberry (B. holstii) plant surveys were conducted by the Biology Department of Addis Ababa University in the northern part of Ethiopia.• In 1978, the Plant Protection Research Center (PRCC) conducted barberry surveys in the north Shewa zone; collected aeciospores were inoculated on wheat seedlings, but no infection was observed.
IntroductionIn 2009, the pathology section of the PPRCconducted B. holstii surveys to investigatewhether the plant functions as an alternate hostto stem rust in Ethiopia.These surveys were carried out in the northernpart of Ethiopia (Shewa zone).
Surveys• In the north Shewa zone, 5 locations were identified where B. holstii grows• These locations range in altitude from 2781- 2895 m• Abundant aeciospores were found on barberry leaves from September to January.
Inoculation results From 6 inoculations, we obtained: Infection Genotype Species (# pustules) McNair 701 Wheat 0 Line E Wheat 1 Morocco Wheat 0 Lemhi Wheat 0 Sr31/6*LMPG Wheat few * Prolific Winter rye Rye Rye many many Hiproly Barley many Hypana Barley many Otana Oat 0* Confirmed in US lab by both inoculation and DNA analysis
ConclusionOur results suggest that B. holstii functions as analternate host to stem rusts of cereals inEthiopia, but this result is preliminary and willrequire confirmation and further study.
AcknowledgementsI wish to acknowledge BGRI/DRRW project for financingthis activity and giving me the opportunity to participatein this Technical Workshop.Inoculation materials and research support weregenerously provided by CDL.
Surveying aecial infections on Berberis spp. in Central RussiaEkaterina S. SkolotnevaMoscow Lomonosov State UniversityAll-Russian Research Institute ofPhytopathology
Barberry survey in the Central Region of Russia (2000-2009) . Sampling locations ... . ... .. .. .. .
• Are there any Berberis spp. in the region?• Yes. B. vulgaris B. purpurea
Barberry bushesField of wheat crops Golicyno-city Barberry bushes B. vulgaris B. purpurea
Dates of disease development in Central Russia May Other months June August July B. vulgarisAugust, 2012: winter wheatNemchinovskaya 24 Agropyron repens
Sampling strategy from barberries Location of bushes = • We consider a location of bushes as a sample Collect fresh aeciospores sample. It may be single bush or Inoculate suscep ble lines group of bushes which are the same species and next to each other oat rye wheat • Only fresh aeciospores are collected Score infected plants for evidence of infection for inoculation • From aecial samples we isolate Susceptible Susceptible Susceptible different formae specialis of Puccinia graminis:Oat stem rust Wheat stem rust is present Rye stem rust is present is present P. graminis f. sp. secalis P. graminis f. sp. avenae P. graminis f. sp. tritici Susceptible alternate hosts to stem rust: B. vulgaris and B. purpurea.
Identification of Pgt races • The International Set of 20 wheat differential lines was used (upgraded in 2006, Prof. Yue Jin, USDA-ARS Cereal Disease Laboratory, University of Minnesota, USA) • From 2000 to 2009 twenty different Pgt races were isolated from barberryB. vulgaris Year Barberry 2000 MKBT, MKLT, MKBP, TKNT, TKLT, RKNT 2001 MKBT, RKDT, PKJG, FKNL, TKNP, TKNT, TKFT 2002 MKBT, MKLT, MKBP, TKNT, 2003 MKNS, TTNT, TKNT, PKNT 2004 TKNT, TTNT,TKST, PKST 2005 TKNT, TTNT, TKST 2006 TKNT, TKPT, TKST, KJNT, RKNT, RKNS 2007 TKNTF, TKSTF 2008 TKNTF, TKNTC, TKSTF 2009 TKNTF, TKNTC, TKSTF
The frequencies of Pgt races isolated from barberry 120 MKBT MKLT TKNP TKFT MKBP TKNT(F/C) TTNT TKST 100 TKPT TKNS TTNS PKST PKNT 80 Race frequency 60 40 20 0 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 Years
SummaryBarberry species distributed in the Central region of Russia wereshown to serve as alternate hosts for stem rust pathogens undernatural conditionsA diversity of stem rust races was isolated from these species.
Alternate hosts paneldiscussion-P. graminis in the presence ofbarberryAnna Berlin
Reported barberryBackground & 2000- 2012law of barberryeradication • The Swedish law of barberry eradication was repealed in 1994 Stockholm • There is no formal survey regarding presence of barberry 100km www.artportalen.se
Harvest planting fall-sown cereals Harvest planting spring cerealsJan Feb Mar Apr May Jun Jul Aug Sept Oct Nov Dec
Markers enable connectingpopulations from the two hostsK=6 data from one structure run Berlin et al. 2012 Phytopathology
X X X X X X Diversity X X X X X X• 30 samples = 30 genotypes X X X• 30 genotypes = ? Races 100 m X X X X X X X X X X X X X X X 30 m
Why no stem rust on wheat?• Barberry present• Severe epidemics on oats and natural grasses• Some rust on rye• Large genotypic variation within and between fields• P. graminis clearly completing its sexual cycle• Does the population identified as P. graminis f. sp. tritici/secalis lack the virulence necessary to infect wheat?• Does wheat grown in Sweden have effective resistance genes?
Research progress on alternate hostand sexual stage of wheat stripe rust in China Zhensheng Kang State Key Laboratory of Crop Stress Biology for Arid Areas, Northwest A & F University,Yangling, Shaanxi, China
Wheat stripe rust (Pst) is a destructive disease throughout all winter wheat regions in China and is considered the most important disease of wheat. Diseased area: between 3-6 million ha. Yield losses: 10-50%.Years Losses (million tonnes)1950 6.01964 3.21990 2.62002 1.4
Based on historical epidemiological data for stripe rust,the wheat-growing regions in China can be divided intothree areas: Western over-summering areas Over-wintering areas Eastern epidemic areas Over-summering areas Over-wintering areas Eastern epidemic areas
In the mountainous western areas, stripe rust can over-summer on volunteer wheat and late-maturing spring wheat.Over-summering areas in south Guansu Volunteer wheat in south Guansu
Hebei Shanxi Shandong Gansu Henan Jiansu Shaanxi Anhui Hubei Sichuan Chongqing oversummerThe migration pathway of P. striiformis in China. movement
The western over-summering areas areconsidered a “hot-spot” for the emergence ofnew races of wheat stripe rust in China. Most new races were first detected in these regions in recent history; A high genetic diversity within the regions’ Pst populations has been reported by different research groups (Lu et al., 2011; Duan et al., 2010; Mboup et al., 2009); The genetic recombination was found to occur for Pst in these regions (Lu et al.,2011; Duan et al., 2010; Mboup et al., 2009).
Why does the western over-summering areas become the “hot-spot” for wheat stripe rust in China? Virulence variation for rusts maybe due to sexual hybridization mutations somatic hybridizationHowever, the mechanism of sexual hybridizationfor wheat stripe rust has been neglected sincethe sexual stage was presumed to be absent.
In 2010, some Berberis spp. were shown to serve asalternate hosts for the wheat stripe rust pathogen. B. chinensis, B. holstii, B. koreana B. vulgaris.
Questions: Does the sexual stage of wheat stripe rust occur under natural conditions, particularly in China? Do any susceptible barberry species coexist with wheat in China? Can wheat stripe rust be isolated from infected Berberis spp. in China? Does the sexual stage of wheat stripe rust contribute to variation in virulence?
Surveys for Berberis spp.in China 215 of the ~500 described Berberis spp. in the world are endemic to China; Many of Chinas Berberis spp. are distributed in the western over-summering areas (hot-spot). Distribution of Berberis species in different regions of ChinaWestern 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;
B. shensiana B. brachypodaBerberis soulieana B. potaninii
Are these Berberis spp.susceptible to wheatstripe rust ?
Identification of Berberis spp. as alternate hosts of wheat stripe rust Dew chamberWe collected seeds and seedlings of Berberis spp. from the fieldand inoculated using telia of Pst in the greenhouse.
Identification of Berberis spp. as alternate hosts of wheat stripe rust Pycnia on BerberisInfection of basidiospore and development of pycnia Normally, we see pycnia on the leaves of susceptible Berberis spp. 11-14 days after inoculation.
Identification of Berberis spp. as alternate hosts of wheat stripe rustAbout 20 days after inoculation, we see aecia develop on the leaves.Aeciospores can infect wheat through the stoma and produce typicalrust symptoms (uredinia).
Species of barberry identified as alternate hosts of Pst by artificial inoculation, using germinating teliospores in ChinaNo. Berberis spp. Orgin Distribution1 B. aggregata Gansu, China Gansu, Sichuan, Hubei, Qinghai, Shanxi2 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. Yunnan, China Gansu, Sichuan,Qinghai,Hubei,Shanxi integrifolia11 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,Henan15 B. poiretii Beijing, China Shaanxi, Qinghai, shanxi, Hebei, Jilin, Liaoning,16 B. guizhouensis Guizhou, China Guizhou
Berberis soulieana B. shensiana 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.
Are any Berberis spp. infected by wheat stripe rust under natural conditions in China? Aecia produced on barberry leaves in natureWe collected 3703 infected- barberry leaves in the fieldsand inoculated wheat with aeciospores in the greenhouse.
Are any Berberis spp. infected by wheat stripe rust under natural conditions in China? Berberis brachypoda B2011-1 B2011-2 B. Shensiana B2011-3 B. Soulieana B2011-4 Four stripe rust cultures (B2011-1, B2011-2, B2011-3, and B2011-4) from three barberry (Berberis spp.) species including B. brachypoda , B. soulieana , and B. shensiana collected from Gansu and Shaanxi Provinces in 2011, respectively. Berberis species Origin Number of Number of uredium-culture aecium-isolate produced on wheat Mingxian 169 Berberis Gansu 1519 2 brachypoda B. shensiana Shaanxi 410 1 B. soulieana Gansu 384 1 B. potaninii Shaanxi 742 0 B. aggregate Gansu 648 0
Can any Berberis spp. be infected by wheat stripe rust under natural conditions in China? A B M M M Ethidium bromide(EB) stained agarose gel showing that four isolates B2011-1, 2011-2,2011-3, and 2011-4 from naturally rust-infected barberry species produced uniform single band amplified using primers ITS-puccinia (5-ACATCGATGAAGAACACAGT-3 )/ITS4( 5- TCCTCCGCTTATTG-ATATGC-3)(left, part A), and specific-primers PSF(5-GGATGTTGAGT-GCTGCTGTAA-3 )/PSR (5‘- TTGAGGTCTTAAGGTTAAAA-TTG-3 ) (right, part B) in accord with race CYR 32 of Puccinia striiformis f. sp. tritici as positive control in size. Sterile water used as negative control (NC). M= 100bp DNA marker DL2000.PCR tests using two Pst-specific primer pairs demonstratethe recovery of four cultures of Pst from Berberis spp.
Comparison of infection types on Chinese differential hosts ofeight major races of Pst and the four Pst cultures recovered from three barberry speciesCultures Differential hosts and Origin of cultures races 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19B2011-1 Berberis brachypoda R S R S S S R S R SR S R R S R R R R RB2011-2 B. brachypoda R S R S S R R S R R S R R R R R R R RB2011-3 B. shensiana R S R S S R S S R RS S R R RS R R R R RB2011-4 B. soulieana R S R R S S R S R R R R R S R S R R RCYR33 Triticum aestivum S S S S S S S S S S S S S S R S R R RCYR32 T. aestivum S S S S S S S S S S S S S S R S S R RCYR31 T. aestivum S S S S S S S S S R S S R S R S S R RCYR30 T. aestivum S S S S S S S S S R S S R R R S S R RCYR29 T. aestivum S S S S S S S S S R S S R R R S R R RCYR28 T. aestivum S S S S S S S S S R S R R R R S R R RCYR23 T. aestivum S S S S R S S S S R S R R R R R R R RCYR17 T. aestivum SR S R SR R SR S R R R RS R R R R R R R R Virulence tests demonstrated that the infection types of the four barberry-derived cultures are different compared to the major Chinese races.
Does the sexual stage under naturalconditions contribute to variation invirulence for wheat stripe rust in China → → → Aecia from Berberry Recovered culture from aecium Single-uredium Virulence test isolates on differentials
Virulence difference among single-uredium isolates fromsingle-aecium-derived culture (B2011-2) on differentials Infection type of single-uredium isolates on differential hosts No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 B2011-2 -1 R S R S R R R S R R S R R R R R R R R B2011-2 -2 R S R R R R R S R R R R R S R R R R R B2011-2 -3 R S R S R R R S R R S R R R R R R R R B2011-2 -4 R S R S R R R S R R S R R S R R R R R B2011-2 -5 R S R R R R R S R R S R R R R R R R R B2011-2 -6 R S R S R R R S R R R R R R R R R R R B2011-2 -7 R S R S S R R S R R S R R R R R R R RThe virulence tests showed high diversity in virulenceamong the single-uredium isolates.
Virulence difference among single-uredium isolates from single- aecium-derived culture (B2011-1) on differentialsNo. Infection type of single-uredium isolates on differential hosts 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19B2011-1-1 RS S R S R S RS S R R R R R S R S R R RB2011-1-2 R S R S S S R S R R R R R S R R R R RB2011-1-3 R R R S S S RS S R RS RS R R S R R R R RB2011-1-4 R S R S S R R S R S R R R S R R R R RB2011-1-5 R S R R R S SR SR R R SR R R S R R R R RB2011-1-6 R S S S R S R S R R S R R S R R R R RB2011-1-7 R S S S S R R S R S S R R R R R R R RB2011-1-8 R S R SR SR S RS S R R RS SR R S R R R RS RB2011-1-9 R S S S S S R S R R RS R R S R R R R RB2011-1-10 R S R S SR S R S R SR SR R R S R R R R RSB2011-1-11 R S S S R S R S R S R R R S R R R R RB2011-1-12 R S R S SR SR R S R R S R R RS R R R R RB2011-1-13 R S S S S S R S R S R R R S R R R R RB2011-1-14 R S R R R S RS S R RS R R R R R R R R RB2011-1-15 R S R S SR S R S R R RS RS R S R R R R RB2011-1-16 R S R S R S R S R RS RS RS R S R RS R R RB2011-1-17 R S S S S S R S R S R R R S R R R R RB2011-1-18 R S R S S S RS S R SR R R R S R R RS R RB2011-1-19 R S R R RS S R S R R RS R R R R R R R RB2011-1-20 R S R S S S R S R SR RS R R RS R R R R RB2011-1-21 R S R S S S R S R SR S R R S R R R R RB2011-1-22 R S R S S S R S R SR S R R S R R R R R
Summary So far, 16 of the 22 tested barberry species from over- summering areas show susceptibility to wheat stripe rust, indicating that there is a great diversity of potential alternate hosts for stripe rust in China. Four cultures of wheat stripe rust were obtained from three barberry species in the field, indicating that the sexual stage of wheat stripe rust occurs under natural conditions in China. Virulence tests for single-uredium isolates recovered from a single aecium demonstrate that the sexual stage contributes to variation in virulence for the wheat stripe rust pathogen in China.
Future Work More barberry species need to be tested for their susceptibility to Pst in China; More field Surveys need to be conducted; More evidence is needed to elucidate the relationship between genetic diversity and the sexual stage of Pst,
Acknowledgement The earmarked fund for Dr. Jie Zhao, Prof. Lili Huang, Modern Agro-industry Dr. Hongchang Zhang, Dr. Dejun Han, Dr. Xiaojie Wang, Dr. Chunfang Wang, Technology Research System in Dr. Qingmei Han, Dr. Jun Gou, China Mrs. Guorong Wei, Dr. Xueling Huang, National Basic Research Dr. Gang Zhang, Dr. Yonghong Zhang, Program of China (973) Dr. Xiumei Yu, Dr. Changqing Chen, Nature Science Foundation of Dr. Liangsheng Xu, Dr. Ninghai Lu, China Dr. Bo Liu, Dr. Jingbiao Ma, The 111 Project from the Mr. Gangming Zhan, Dr. Wenming zheng Chinese Ministry of Education All Ph D and Master studendts in My Lab.Dr. X M. Chen, Dr. H. Buchenauer,Dr. Robert McIntosh , Dr. ColinWellings, 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
Berberis rust survey in the Ug99 pathway in CWANAKumarse Nazari ICARDAAnnemarie F. Justesen GRRC, Aarhus UniversityJens Grønbech Hansen GRRC, Aarhus UniversityDave Hodson CIMMYTMehran Patpour, Farzad Afshari, Seed and Plant Improvement Institute, Karaj IranHojjatollah Rabbani Nasab North Khorassan Agricultural and Natural ResourceZoia Sikharulidze Institute of Plant Immunity from GeorgiaAmir Amanov, Zafar Ziyaev Kashkadarya Grain Breeding and Seed Production Institute, UzbekistanAtiq ur Rehman Rattu National Agricultural Research Centre, PakistanHukmatullo Ahmadov, Mahbubjon Rahmatovm, Bahiram Tajik Academy of Agricultural SciencesKonul Aslanova Agrarian and Animal Husbandry Research Institute, Azerbaijan
Methodology•Berberis survey and biological assays•Photo documentation of the Berberis host•Leaf sample collection of Berberis spp.•DNA-extraction from single aecial pustules,several pustules from each barberry plant•PCR amplification of EF1α- and/or β-tub-gene•Species identification by sequence comparisons tosequences in GenBank and reference sequencesfrom grass and cereal hosts
DNA sequence data obtained so far:•Iran: 12 sequences (2010), 4 (2012)•Tajikistan : 24 sequences (2011)•Uzbekistan: 7 sequences (2012)•Azerbaijan : 6 sequences (2012)
Preliminary results• Two main clusters: P. graminis and P. striiformis•Within the P. graminis cluster, sequences show 94-95%identity to Pgt sequences in GenBank•All sequences within the P. striiformis cluster are fromTajikistan and show 99-100% identity to P. striiformisf.sp. dactylis (P. striiformoides), none are identical to P.striiformis f.sp. tritici
Future workContinue sequencing of more aeciaSequence β-tubulin or ITS in order to be able to identify hostorigin based on sequences in GenBankObtain more reference sequences from grasses??
Looking for the Source of Pathogen Variability in Stem andStripe Rusts—the Barberry Connection --- Knowledge Gaps and Challenges Yue Jin USDA-ARS Cereal Disease Laboratory University of Minnesota, St Paul, Minnesota, USA
“Cereal rusts are the most-researched plant diseases” “A large body of literature exists”
“Cereal rusts are the most-researched plant diseases” “A large body of literature exists”Interpretation: there are no more mysteries!
“Does barberry play a role in pathogen variation and diseaseepidemiology in stem rust and stripe rust?”e.g. the Kenya example: Are there barberries? ----- Yes (B. holstii) Is B. holstii susceptible to stem rust? ----- Yes Does B. holstii function as an alternate host in Kenya? ----- Do not know
“What is the species?”Is there any taxonomic support when we encounter unknown species? Can we develop a robust assay to identify Berberis spp.?
The Barberry Connection:Looking for the source of pathogenvariability in stem and stripe rusts
Sr31 virulence Sr31 + Sr24 (Kenya) detected in Uganda (Ug99) Sr31 + Sr36 (Kenya) 2000 2004 2008 2012 Ethiopia Iran S. Africa Eritrea Ug99Uganda Kenya Sudan Tanzania Yemen Zimbabwe races Sounding the Alarm Global Rust Initiative (GRI) 1. Race surveillance 2. Resistance screening 3. Breeding 4. Chemical control 5. Seed production 6. Impact assessment 7. Training 8. Infrastructure (E. Africa) 9. Reporting and communication 10. Resources for IARCs
Sr31 virulence Sr31 + Sr24 (Kenya) detected in Uganda (Ug99) Sr31 + Sr36 (Kenya) 2000 2004 2008 2012 Ethiopia Iran S. Africa Eritrea Ug99Uganda Kenya Sudan Tanzania Yemen Zimbabwe races Sounding the Alarm Sexual populations of wheat stripe rust found in China East African native barberry (B. holstii) Barberry spp. shown shown to be susceptible to function as alternate to stem rust hosts to wheat stripe rust Aecial infections on B. holstii shown to be B. holstii found in susceptible to stripe rust East Africa Sexual populations of wheat stem rust found on Mahonia spp. in PNW Sexual populations of oat stem rust found in Sweden
The Barberry Connection:Looking for the source of pathogenvariability in stem and stripe rusts A Berlin, Sweden Y Jin, USA ZS Kang, China K Nazari, ICARDA, Syria E Skolotneva, Russian Federation R Wanyera, KARI, Kenya G Woldeab, EIAR, Ethiopia