L'accès à la plateforme Érudit connaît actuellement un ralentissement, dû à un incident chez notre prestataire technique. Nous sommes désolés de ce désagrément et collaborons activement à rétablir le service. L'information sera mise à jour sur notre pageTwitter

Communications brèvesShort Communications

Assessment of powdery mildew (Blumeria graminis f. sp. hordei) resistance genes in Turkish barley varieties

  • Ahmet Zeybek,
  • Şahin Dere,
  • Gülay Gök,
  • Asude Çallak et
  • Mahinur S. Akkaya

…plus d’informations

  • Ahmet Zeybek
    Middle East Technical University,
    Department of Chemistry,
    Plant Functional Genomics Laboratory,
    Ankara,
    TR-06531,
    Turkey
    and Mugla University,
    Fethiye Technical Agricultural College,
    Mugla,
    TR-48300,
    Turkey

  • Şahin Dere
    Middle East Technical University,
    Department of Chemistry,
    Plant Functional Genomics Laboratory,
    Ankara,
    TR-06531,
    Turkey
    and Ordu University,
    Agricultural Faculty,
    Department of Field Crops,
    Ordu,
    TR-52200,
    Turkey

  • Gülay Gök
    Middle East Technical University,
    Department of Chemistry,
    Plant Functional Genomics Laboratory,
    Ankara,
    TR-06531,
    Turkey

  • Asude Çallak
    Middle East Technical University,
    Department of Chemistry,
    Plant Functional Genomics Laboratory,
    Ankara,
    TR-06531,
    Turkey

  • Mahinur S. Akkaya
    Middle East Technical University,
    Department of Chemistry,
    Plant Functional Genomics Laboratory,
    Ankara,
    TR-06531,
    Turkey
    akkayams@metu.edu.tr

Logo de Phytoprotection

Corps de l’article

Dedicated to the memory of Dr. Şahin Dere.

Barley (Hordeum vulgare L.) is the fourth most important cereal crop in the world, after wheat, maize and rice. Turkey is among the main barley producing countries, ranking ninth in the world (Anonymous 2005). Powdery mildew caused by the fungal pathogen Blumeria graminis (DC.) Golovin ex Speer f. sp. hordei Em. Marchal (synamorph Erysiphe graminis DC. f. sp. hordei Em. Marchal) is one of the most destructive leaf diseases of this crop in regions with coastal climatic conditions, including the western and southern parts of Turkey. This disease lowers product quality and causes grain yield losses of up to 25-30%. Yield losses due to powdery mildew have been estimated at ~1 M ha yr‑1 in Europe (Czembor and Czembor 2001).

In Turkey, powdery mildew epidemics usually occur in the western and southern parts of the country, especially when the spring season is cool and rainy. In recent years, epidemics have also become a problem under dry and hot climatic conditions due to the increased use of irrigation set-ups and nitrogen fertilizers. The control of powdery mildew in Turkey relies on fungicides - in some areas - and breeding for host resistance. The development of resistant cultivars, however, has not been pursued extensively as of yet, even though this control approach is generally considered cost effective and environmentally safe (Wolfe 1984; Wolfe and McDermott 1994).

Race-specific resistance to powdery mildew is governed by major resistance genes (or R-genes) that can be introgressed from resistant varieties into susceptible cultivars of agronomic interest. The best potential sources of new resistance genes for cultivated barley most likely are landraces from the centre of origin (Ceccarelli et al. 1987, 1995). The Fertile Crescent area, covering the southeastern part of Turkey, is considered as the centre of origin for barley and wheat (Czembor 1996; Willcox 1995; Zohary 1999), which suggests that barley varieties, landraces and wild relatives from Turkey might represent an interesting source of R-genes for powdery mildew (Jahoor and Fishbeck 1987). Until now, nearly all European barley cultivars have been assessed for the presence and identity of R-genes to powdery mildew, making it possible to conclude to the presence of one or two R-genes in most varieties. Although the interaction between powdery mildew and barley is often regarded as one of the best characterized host-pathogen systems, and although many resistance alleles have already been identified (Kolster et al. 1986), the identification of R-genes for this disease in Turkish barley varieties and landraces still remains incomplete.

As a first step towards the effective use of powdery mildew R-genes in breeding programs, it is essential to test for the presence of those genes in registered cultivars and for the virulence of the pathogen through periodical surveys (Czembor and Bladeno-poulos 2001; Czembor and Czembor 1998, 2000a; Czembor and Gacek 1990; Czembor and Johnston 1999). In practice, such surveys are conducted based on the gene-for-gene hypothesis, i.e. by inoculating plants with pathogen isolates that present a defined virulence spectrum (Flor 1942, 1955; Moseman 1959). The infection spectra observed make it possible to determine a ’reaction spectrum’ for each interaction, which then makes it possible to identify the resistance phenotype of the tested plant (Czembor and Czembor 1998, 1999, 2001; Dreiseitl and Jørgensen 2000). Although Turkish varieties probably possess a number of unidentified and/or still uncharacterized R-genes for powdery mildew, monitoring has not yet been done on a systematic basis. As an attempt to provide useful information for future breeding efforts, the objective of this study was to identify major powdery mildew R-genes in barley varieties grown in Turkey.

Seed samples from 34 barley cultivars were provided by the Aegean Agricultural Research Institute of Turkey. A list of the varieties tested and their origin is presented in Table 1. All barley cultivars in this study were of the spring type, with six- and two-row heads, covered kernels, and an intermediate heading date. These cultivars are grown in the Aegean and Mediterranean coastal regions. In this experiment, the plants were grown at 20-22°C in a growth room under a 14h:10h light/dark photoperiod, until they reached the second leaf stage. The leaves of these seedlings were used for the “leaf segment test” (Lutz et al. 1992) (see below).

Table 1

Registration number (RN), variety name, and botanical name of the 34 Turkish barley varieties assessed in this study

Number

RN

Variety name

Botanical name

1

TR41009

Zafer 160

Hordeum vulgare vulgare

2

TR41010

Yesilköy 387

Hordeum vulgare vulgare

3

TR41011

Gemici 7243

Hordeum vulgare vulgare

4

TR41012

Kaya 7794

Hordeum vulgare distichon

5

TR45288

Tokak 157/37

Hordeum vulgare distichon

6

TR45289

Cumhuriyet 50

Hordeum vulgare distichon

7

TR45290

Yerçil 147

Hordeum vulgare distichon

8

TR50882

Hamidiye 85

Hordeum vulgare distichon

9

TR50883

Obruk 86

Hordeum vulgare distichon

10

TR50884

Anadolu 86

Hordeum vulgare distichon

11

TR50885

Bülbül 89

Hordeum vulgare distichon

12

TR57795

Efes-1

Hordeum vulgare distichon

13

TR57796

Efes-2

Hordeum vulgare distichon

14

TR57797

Efes-3

Hordeum vulgare distichon

15

TR57786

Sahin 91

Hordeum vulgare distichon

16

TR57790

Yea. 793.12

Hordeum vulgare distichon

17

TR68592

Bornova 92

Hordeum vulgare nutans

18

TR68593

Serife hanım 98

Hordeum vulgare

19

TR69697

Vamık hoca 98

Hordeumvulgare agriacrithom

20

TR69698

Akhisar 98

Hordeum vulgare agriacrithom

21

TR69699

Süleyman bey 98

Hordeum vulgare nutans

22

TR69700

Bilgi 91

Hordeum vulgare

23

TR72333

Beysehir 98

Hordeum vulgare

24

TR72334

Konevi 98

Hordeum vulgare

25

TR72338

Basgöl

Hordeum vulgare

26

TR72340

Çıldır-02

Hordeum vulgare

27

TR72342

Avcı-2002

Hordeum vulgare

28

TR72343

Yesevi-93

Hordeum vulgare

29

TR72344

Orza-96

Hordeum vulgare

30

TR72345

Aydan hanım

Hordeum vulgare

31

TR76583

Özdemir 05

Hordeum vulgare

32

TR76584

Ince 04

Hordeum vulgare

33

TR76585

Kalaycı 97

Hordeum vulgare

34

TR76586

Erginel 90

Hordeum vulgare

-> Voir la liste des tableaux

Nine isolates of Blumeria graminis were used as differentiating races for resistance tests (Table 2). These isolates were obtained from collections of the Riso National Laboratory of Denmark, and chosen based on their virulence spectrum as observed on the Pallas isogenic differential line set (Kolster et al. 1986). The fungi were provided by Dr. M.S. Hovmøller (Royal Agricultural and Veterinary University, Denmark) as purified single spore isolates, maintained and propagated on young seedlings of the powdery mildew-susceptible cultivar Cartegana.

Table 2

Isolates of Blumeria graminis f. sp. hordei and their infection types on ’Pallas’ differential near-isogenic lines (Kølster et al. 1986) and 12 additional cultivars

No

Differential lines1

R‑genes

Differential test isolates2

B4(C15)

B95(53/01)

B100(60/01)

B121(26/04)

B120(20/04)

B97(57/01)

B91(98AF066)

B21(R86/01)

B103(64/01)

0

Pallas

Mla8

4

4

4

4

4

4

4

4

4

1

P01

Mla1,ML (A12)

0

4

4

4

0

0

0

0

0

2

P02

Mla3,

4

0‑1n

0

0

4

4

0‑1n

4

0‑1n

3

P03

Mla6, Mla14

0

0

0‑1n

3n‑4

4

4

0

4

4

4

P04B

Mla7, Ml(NO3)

0

4

4

3‑4

1‑2n

3n

4

1n

4

5

P08B

Mla9

0

0

4

4

4

0

4

0

0

6

P09

Mla10, Ml (Du2)

0

4

3n

0

4

0

4

0

0

7

P10

Mla12, Ml (Em2)

0

4

0‑1n

1n

3n‑4

4

1n

0‑1n

3n‑4

8

P11

Mla13, Ml (Ru3)

0

0

0

4

0

4

4

0

4

9

P12

Mla22 Mic)

4

0

0

3n‑4

0

4

0

4

0

10

P14

Mlra

4

4

4

0

4

4

4

4

4

11

P16

Mlk

2cn

2cn

4

1‑2cn

4

1‑2cn

3n‑4

1‑2cn

3n‑4

12

P20

Ml

2n

2n

2n

2‑3n

2n

4

1‑2n

1‑2cn

2n

13

P21

Mlg,Ml (CP)

2‑3n

4

4

4

4

4

4

0

4

14

P23

Mlla

1‑2n

4

4

4

4

2n

4

4

2n

15

P24

Mlh

4

4

0

0

4

4

4

4

4

16

ISO2R

Mlg

4

4

4

4

4

4

4

1‑2n

4

17

SI‑1

Sl 1

0

1‑2n

3n

0

0

0

0

0

0

18

GUNNAR

Mla3, Ml (Tu2)

1‑2n

0

0

0

2n

4

2‑3n

4

0

19

SV83380

Mlab

2n

3n

2‑3n

3n

4

4

3n‑4

2n

4

20

MELTAN

Mla13, Mlı 8lm9),+

0

0

0

4

0

4

0

0

4

21

GOLDIE

Mla 12, U

0

2n

0

4

1n

4

4

0

4

22

STEFFI

Ml (St)

0

0‑1n

0‑1n

3n

4

2n

4

0

1n

23

HENNI

 

0

1‑2n

0‑1n

4

4

1n

4

0

1‑2n

24

PUNTO

Mla3, Ml (Tu2), Ml (lm9),+

0

0

0

0

1n

4

1‑2n

1n

0

25

BENEDIKTE

Mla9, Ml(lm9)

0

0

2n

4

0‑1n

0

1n

0

0n

26

SCARLETT

 

0

0‑1n

0

3cn

4

2n

4

0

0‑1n

27

CARLSBERG

Mla8

4

4

4

4

4

4

4

4

4

28

Bülbül 89 / control

 

4

4

4

4

4

4

4

4

4

1

P01-P24: Pallas differential near-isogenic lines.

2

Scale 0-4: 0 = not compatible; 4 = compatible; n = necrosis; c = chlorosis.

-> Voir la liste des tableaux

The infection type of the isolates was assessed on host leaves using 3-cm-long leaf segments cut from the middle part of the primary leaf of 12-d-old seedlings laid on benzimidazole-containing agar (35 ppm benzimidazole in 1.5% agar). Inoculations were performed using a homemade mini-settling tower. The leaf segments inoculated on agar plates were placed in a growth chamber at 17-18°C under a 12h:12h light/dark photoperiod. Infection types were scored after 10 d according to the 0-4 scale of Welz (1988) (Table 3). Leaf segments with infection types (or scores) of 0, 1 or 2 were classified as resistant to the fungus; leaf segments with scores of 3 or 4 were classified as susceptible.

Table 3

Infection types (IT) based on the symptoms observed (Welz 1988)

IT

Symptoms

0

No visible symptoms (immunity)

1

Necrotic flecks, usually minute; no mycelial growth; no sporulation (hypersensitivity)

2

Frequent chlorosis; reduced mycelial growth; no or very scarce sporulation

3

Moderate mycelial growth; moderate sporulation; sometimes chlorosis

4

Profuse sporulation of well-developed colonies and sometimes green islands

-> Voir la liste des tableaux

Specific R-genes associated with each genotype were inferred by comparing their reaction spectrum with that of previously characterized differential lines (Brown and Jørgensen 1991; Czembor and Bladenopoulos 2001). Identifications were done based on the gene-for-gene hypothesis (Flor 1942, 1955). When a compatible reaction was observed with a given isolate (scores 3 and 4), it was inferred that the tested cultivar did not possess the resistance allele(s) for which the isolate was avirulent. Incompatible reactions (scores 0-2) with isolates possessing only one avirulence allele among the remaining possible resistance alleles then made it possible to postulate that the matching resistance allele was present (Czembor and Czembor 2001; Dreiseitl and Jørgensen 2000). Table 4 presents putative resistance alleles for the 34 barley varieties tested.

Table 4

Resistance alleles and infection types of 34 Turkish varieties challenged with nine isolates of Blumaris graminis f. sp. hordei

No

Cultivars

Differential test isolates

Postulated alleles

B4(C15)

 

B95(53/01)

 

B100(60/01)

 

B121(26/04)

 

B120(20/04)

 

B97(57/01)

 

B91(98AF066)

 

B21(R86/01)

 

B103(64/01)

 

1

Zafer 160

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

Mla8

2

Yesilköy 387

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

Mla8

3

Gemici 7243

3

3

1

0

2

2

4

4

4

4

2

2

4

4

3

3

3

3

+?

4

Kaya 7794

0

1

4

3

3

2

4

4

3

3

2

2

4

4

2

2

4

4

Mla (La)

5

Tokak 157/37

3

2

4

4

2

2

4

4

4

4

4

4

4

4

0

0

4

4

Mlg, Ml (CP)

6

Cumhuriyet 50

3

3

4

4

2

2

4

4

3

2

4

4

4

4

3

3

4

4

+?

7

Yerçil 147

0

0

2

3

2

2

4

4

4

4

2

2

4

4

0

0

4

4

+?

8

Hamidiye 85

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

None

9

Obruk 86

4

3

4

3

1

0

0

0

4

4

4

4

4

4

4

4

4

4

Mlh

10

Anadolu 86

4

4

4

4

0

0

4

4

2

2

4

4

4

4

4

4

4

3

Mlh +?

11

Bülbül 89

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

None

12

Efes-1

4

3

4

3

2

0

4

4

0

1

2

2

4

4

4

4

3

2

Mla1 +

13

Efes-2

3

4

4

3

3

4

4

4

4

3

4

4

4

4

4

4

4

4

Mla 8

14

Efes-3

3

3

4

3

2

2

4

4

2

2

4

4

4

4

4

4

4

2

Mla +?

15

Sahin 91

4

4

4

4

3

3

4

4

4

4

4

4

4

4

4

4

4

4

Mla8

16

Yea. 793.12

4

4

4

4

4

4

3

3

3

2

2

2

4

4

4

4

4

4

+?

17

Bornova 92

0

0

4

4

4

4

4

4

1

0

0

0

0

1

0

0

1

0

Mla 1+ ?

18

Serife hanım 98

0

0

3

3

3

2

4

4

1

2

4

4

4

4

2

2

4

3

Mla 7+?

19

Vamık hoca 98

2

3

4

4

2

2

2

2

2

1

2

3

4

4

3

2

4

3

MlAb

20

Akhisar 98

3

2

4

4

3

3

3

2

2

1

4

4

4

4

4

4

3

2

+?

21

Süleymanbey 98

1

2

3

3

4

4

4

4

4

4

4

4

4

4

4

3

4

4

MlAb+?

22

Bilgi 91

4

4

4

4

4

4

4

4

4

4

4

4

4

4

0

1

4

4

Mlg

23

Beysehir 98

3

2

4

4

4

4

4

4

4

4

4

4

4

4

0

0

4

4

Mlg, Ml (CP)

24

Konevi 98

3

3

4

4

4

4

4

4

4

4

4

4

4

4

0

0

4

4

Mlg, Ml (CP)

25

Basgöl

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

Mla 8

26

Çıldır-02

3

3

4

4

0

0

0

0

4

4

4

4

4

4

4

4

4

4

Mlh

27

Avcı-2002

0

2

4

4

3

4

4

4

4

4

4

4

4

4

4

4

4

4

Mla7

28

Yesevi-93

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

None

29

Orza-96

4

4

4

4

0

2

4

4

4

4

4

4

4

4

4

4

4

4

Mlra

30

Aydan hanım

4

4

4

4

4

4

0

0

4

4

4

4

4

4

4

4

4

2

Mlg

31

Özdemir 05

4

4

4

4

0

0

0

0

4

4

4

4

4

4

4

4

4

3

Mlh

32

Ince 04

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

3

Mla 8

33

Kalaycı 97

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

Mla 8

34

Erginel 90

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

4

Mla 8

Each cultivar was tested as two replicates with each test isolate.

-> Voir la liste des tableaux

This study is, to our knowldege, the first to identify R-genes for powdery mildew in commonly grown barley cultivars bred in the National Agricultural Research Institutes of Turkey. The presence of several R-genes was inferred among the varieties tested, including Mla8, MlLa, Mlg, Ml(CP), Mlh, Mlat, Mla1, Mlh, Mla7, Mlra, and a few uncharacterized genes. The most common R-gene was Mla8; it was found in nine cultivars out of 34 (Zafer-160, Yesilköy 387, Efes-2, Sahin-91, Basgöl, Yesevi-93, Ince-04, Kalaycı-97, and Erginel 90). Several cultivars contained a single (known) R-gene for powdery mildew [namely Orza-96 (Mlra), Serife hanım (Mla7), Bornova-92 (Mla1), Kaya-7794 (Mla(La)), Bilgi 91 (Mlg), Vamık hoca-98 (Ml(Ab)), Sülayman bey-98 (Ml(Ab)), Obruk-86 (Mlh), Özdemir 05 (Mlh), Çıldır 02 (Mlh), and Anodulu-86 (Mlh)], while three cultivars (Tokak-157/37, Beysehir-98, and Konevi-98) contained both Mlg and Ml(CP). Interestingly, the varieties Gemici-7243, Yea-793.12, and Akhisar-98 were partly resistant to the fungus, but no R-gene could be inferred because their reaction spectra with the test isolates were not conclusive. By contrast, the cultivars Hamidiye-85, Yesevi-93, and Bülbül-89 showed no resistance to any of the isolates tested, as also observed by Lower et al. (1997).

Compared with other studies on R-genes in barley cultivars or landraces, the number of distinct R-genes postulated here is relatively large considering the limited number of cultivars tested (10 different genes in 34 cultivars). Of these genes, none had previously been detected in barley landraces from Morocco (Czembor and Czembor 2000a, b), and the previously described R-genes detected in landraces from Greece, such as Mla6, Mla14 or Mlat, were not found in the varieties tested in the present study (Czembor 2001). By contrast, the genes Mlg, Mlak, Mla7, and Mla(Ab) have also been detected in North American cultivars (Dreiseitl and Steffenson 2000). Likewise, the genes Mlg, Mlk, Mla7, MI(CP), and Mla1 were previously detected in a population of 108 Baltic spring barley cultivars and breeding lines (Tueryapina et al. 1996), the genes Mla1, Mla7, and Mlk were detected in Tunisian landraces (Czembor and Johnston 1999), and the genes Mlg and Mla7 were detected in a population of 20 cultivars from Greece (Czembor and Bladenopoulos 2001). Based on these previous reports and on the present study, the most commonly found R-genes for powdery mildew in barley appear to be Mlg, which has been introduced into many European cultivars a long time ago, and Mla7, which has also been introduced into common barley varieties over the years.

The identification of R-genes based on tests performed using leaf segments and fungal isolates with different virulence spectra is an effective and useful tool for plant breeders (Russel 1978). Based on our data, it can be concluded that Turkish barley cultivars possess several genes for resistance to powdery mildew that can be used as parental plant materials in different gene deployment strategies aimed at efficiently controlling powdery mildew through gene pyramiding. None of the cultivars assessed in the study showed resistance based on the gene Mlo, which is known to provide efficient monogenic, non-race-specific and durable resistance (Hovmøller et al. 2000; Jørgensen 1992, 1994). Future work for barley breeders in Turkey should now focus on pyramiding this gene with the newly described Ml genes.

Parties annexes