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Mlo Resistance to Powdery Mildew (Blumeria graminis f. sp. hordei) in Barley Landraces Collected in Yemen

by
Jerzy H. Czembor
* and
Elżbieta Czembor
Plant Breeding and Acclimatization Institute—National Research Institute (IHAR-PIB), Radzikow, 05-870 Błonie, Poland
*
Author to whom correspondence should be addressed.
Agronomy 2021, 11(8), 1582; https://doi.org/10.3390/agronomy11081582
Submission received: 5 July 2021 / Revised: 4 August 2021 / Accepted: 5 August 2021 / Published: 9 August 2021
(This article belongs to the Special Issue Crop Powdery Mildew)

Abstract

:
Barley (Hordeum vulgare L.) is one of the most important cereal crops in the world. Powdery mildew on barley, which is caused by the pathogen Blumeria graminis f. sp. hordei, occurs world-wide and can result in severe yield loss. Thousands of barley accessions are stored in national gene banks, and their characterization for breeding purposes is needed. This study was conducted to determine the resistance to powdery mildew in 33 barley landraces from Yemen, which were obtained from the ICARDA gene bank. Twenty differential isolates of barley powdery mildew were used. Nine single plant lines were selected from five landraces, based on tests that were performed with 30 plants per landrace, after inoculation with the most avirulent isolate of barley powdery mildew available. Two of these landraces originated from the Al Bayda province in Yemen, and three others originated from Dhamar, Sanaa, and Taizz, respectively. Next, single plant lines were tested using a set of 20 differential isolates of powdery mildew. Two lines that were selected from landrace from the Al Bayda province in Yemen, showed disease reaction designated as 0(4), which is specific for the presence of Mlo resistance. The new source of highly effective Mlo powdery mildew resistance that is described in this study could be used in barley breeding programs.

1. Introduction

Barley (Hordeum vulgare L.) is the fourth most important cereal crop in the world. In many regions, barley is often grown in marginal agricultural areas with low annual precipitation (often less than 220 mm). Landraces in these areas are important, as they are often the only rain-fed crop possible and they are cultivated on mountain slopes, at elevations higher than other cereals. They are often grown not only for grain, but also for straw [1]. More than 485,000 accessions of the genus Hordeum are stored at more than 200 institutions worldwide [2]. These collections include new and old cultivars, landraces, mutants, breeding lines, and research and mapping plant materials of H. vulgare ssp. vulgare (299,165 accessions), wild barley H. vulgare ssp. spontaneum (32,385 accessions), and wild species of Hordeum (4681 accessions) [3]. Because of quarantine issues and safety reasons, many accessions are duplicated in gene banks. These genetic resources are of great value for breeding new cultivars that are well adapted to changing climate and weather anomalies, or more resistant to abiotic and biotic stresses [4,5,6].
The fungus Blumeria graminis (DC.) Golovin ex Speer f. sp. hordei Em. Marchal is considered to be one of the most destructive foliar pathogens of barley in many regions of the world. In countries where mildew is a problem, yield losses in experimental tests usually exceed 25%. However, the average annual losses in barley production are lower, and in Central Europe they are estimated to be about 10% [7]. The best means of controlling powdery mildew was using resistance genes. However, the resistance that is conferred by most of these genes has not been maintained for more than a few years (5–10 years), with one exception, which is Mlo resistance [8,9,10,11]. Mlo resistance is a unique type of resistance, because it is monogenic and non-race-specific. The recessive alleles at the Mlo locus condition the penetration resistance of the attacked epidermal cells, by rapid deposition of large callose-containing appositions (papillae) in the epidermal cell wall, directly subtending the attacking fungal appressoria. This resistance reaction is only characteristic for mlo alleles, and is designated as 0(4). The mlo locus was genetically mapped, and its molecular structure was described and patented. However, many factors, e.g., temperature, water stress or light intensity, may affect the expression of this gene. Negative pleiotropic effects that were common when mlo was used in earlier crosses have been overcome by recent breeding, and this type of resistance is presently utilized with increasing intensity in spring barley production. During the last 35 years, Mlo resistance has been deployed in many barley cultivars throughout Europe [12,13,14,15,16]. These investigations are conducted to increase the resistance durability [16,17,18,19,20,21,22].
Yemen is characterized by the presence of diverse agroecological zones and a long history of agriculture. Based on different landscapes, Yemen can be divided into the following five main geographical regions: the coastal plains (with rainfall below 50 mm/year), mountains and highlands (with rainfall on average 300–500 mm/year, but in some places more than 1 000 mm/year), the eastern plateau region (with rainfall below 100 mm), the desert, and the islands [23]. The cultivable land in Yemen is estimated to be about 7% of the total area. The largest part of the agricultural activities is in the Yemen highland and mountain area, in the western part of the country. The highlands of Yemen are characterized by their stone-wall terraces. These terraces represent over 40 percent of the country’s arable land [24].
Cereals are grown on almost 60% of the total cultivated area, and barley is grown on about 50,000 hectars. In Yemen, barley is grown at 1800–3000 m above sea level [1,25].
Genetic studies on resistance to diseases, including barley powdery mildew, is valuable for breeding programs and characterization of germplasm collections [26,27,28]. Identification of powdery mildew resistance genes, based on tests performed on seedlings, using isolates with different virulence spectra, is effective and sufficient for breeders and pathologist needs [22,23,29]. This study aimed at detecting new sources of powdery mildew resistance in barley landraces that were collected from Yemen, based on the results obtained during testing lines that were selected from these landraces with a set of powdery mildew isolates with different virulence.

2. Materials and Method

2.1. Plant Material

Thirty-three seed samples of barley landraces were provided by Dr. J. Valkoun, J. Konopka and Prof. S. Ceccarelli (International Center for Agricultural Research in the Dry Areas—ICARDA). These landraces were collected in Yemen, mostly in central mountains area of the country in 7 provinces (10 landraces from Dhamar, 6—Taizz, 6—Sanaa, 2—Sadah, 4—Al Bayda, 2—Al Hudayah and 3—Ibb) (Table 1).

2.2. Pathogen

To determine the R-genes present in landraces lines, 20 Bgh (B. graminis f. sp. hordei Em. Marschal) isolates, with virulence genes corresponding to known resistance genes, were used (Table 2). Isolates originated from the collections in Risø National Laboratory, Roskilde, Denmark; Danish Institute for Plant and Soil Science, Lyngby, Denmark; Edigenossische Technische Hochschule—ETH, Zurich, Switzerland, provided kindly by Dr. H.J. Schaerer (ETH, Zurich, Switzerland), and Plant Breeding and Acclimatization Institute—National Research Institute (PBAI-NRI) IHAR-PIB Radzików, Poland. The isolates were chosen according to differences in virulence spectra that were observed on the Pallas isolines differential set, provided by Dr. L. Munk (Royal Agricultural and Veterinary University, Copenhagen, Denmark) and on 12 additional cultivars. Each of them represent different pathotypes, determined using a selected set of 20 Pallas isolines differential and Trumph and Gunnar cultivars. Isolate Bgh 33 was the most avirulent one. It was avirulent to resistance genes or their combinations, such as the following: Mla1, Mla3, Mla6 + Mla14, Mla7 + Mlk + ?, Mla7 + ?, Mla7 + MlLG2, Mla9 + Mlk, Mla9, Mla12, Mla13 + MlRu3, Mla22, Mla23, MlRu2, Mlk, Mlp, Mlat, and present in additional cultivars included into a differential set, as follows: Benedicte (Mla9, Ml (IM9)), Lenka (Mla13, Ml (Ab)), Gunnar (Mla3, Ml (Tu2)), Steffi (Ml (St1)), Ml (St2)), Kredit Ml (Kr). Isolates Bgh 3, Bgh 1, Bgh 29, Bgh 51 belong to the most virulent group.
Isolates were purified by single pustule isolation and were maintained and propagated on young seedlings of the powdery mildew-susceptible cultivar Manchuria (CI 2330). Frequent virulence checks were made to assure the purity of isolates throughout the experiment.

2.3. Landraces and Single Plant Lines Resistance Tests

Approximately 30 plants per landrace were evaluated with the Bgh 33 isolate, under controlled chamber conditions with a 16/8 h day/night photoperiod and a 22/16 °C temperature regime.
Seedlings with a fully expanded first leaf (two-leaf stage) were inoculated with powdery mildew by shaking conidia from the susceptible cv. Manchuria. After 8–10 days, infection types were scored. A five-point (0 to 4) reaction type (RT) scale was used, as follows: 0, no visible symptoms; 1, minute necrotic flecks, no mycelial growth and no sporulation; 2, frequent chlorosis, reduced mycelial growth and no, or very scarce, sporulation; 3, moderate mycelial growth, moderate sporulation, and occasional chlorosis; 4, profuse sporulation of well-developed colonies, 0(4) sparse small colonies originating from the stomatal subsidiary cells [29,30,31,32]. Plants with disease scores of 0 to 1 were classified as highly resistant (R), plants that scored 2 as a moderately resistant (M), and rating of 3 or 4 as susceptible and very susceptible. Plants scored 0(4) possess the mlo5 gene. The cultivar Manchuria was used as a susceptible control.
In the group of plant material from Yemen there were 6 single plant lines selected from 5 landraces, and which were classified as highly resistant and moderately resistant to powdery mildew. They were grown in greenhouse conditions to obtain seeds for future evaluations using a set of 20 Bgh isolates. Postulation of resistant genes was based on a comparison of reaction spectra designated on landraces lines and the barley differential set (Table 2).
The possibility of the presence of resistance genes was concluded on the basis of the gene-for-gene hypothesis [33]. The infection response spectrum of each landrace was compared with the Bgh virulence spectrum previously found on the set of barley differential varieties.

3. Results

Among 33 landraces from Yemen, 7 (21,2%) expressed resistance to isolate Bgh 33 of B. graminis f. sp. hordei (Table 3). Two of these landraces (5589, 5590) originate from the Al Bayda province of Yemen, and three others originate from Dhamar (5605), Sanaa (5607), and Taizz (5616), respectively.
Among the landraces from Yemen, the plants belong to seven lines selected from, five landraces were classified as highly resistant, moderately resistant, and which were evaluated using set of 20 Bgh isolates, which possess virulence genes that correspond to known resistance genes (Table 3).
The seedling leaves of two lines, 5589-1-1 and 5590-1-1, showed no visible signs of infection, except for occasional infection type 4 (compatible) mildew colonies. These colonies were also about half of the size in comparison to those observed on the susceptible control cultivar Manchurian. Such a reaction was designated as 0(4). This reaction type is characteristic for Mlo resistance, and is described as follows: sparse small colonies originating from the stomatal subsidiary cells. In addition, the young leaves of these lines were investigated under a microscope. It was observed that, in almost all cases (with two exceptions), mildew colonies originated from a successful infection in the subsidiary cells next to the stomata on the barley epidermis. Based on these observations, the possibility of mlo allele presence in these selections was postulated. Another highly resistant line was line 5607-1-1, which showed resistance reaction zero after infection with two isolates. Three other lines were susceptible to infection with isolate three. Six tested lines were classified in four groups according to their resistance spectrum. It was not possible to postulate the presence of specific resistance genes in four lines (5598-1-1, 5598-4-2, 5605-1-1, and 5607-1-1).

4. Discussion

Landraces are the easiest to use directly in breeding programs, because there are no problems in conducting crosses. They are genetically heterogeneous, dynamic populations. They come from regions with traditional agricultural culture, where there are no active systemic breeding programs [34]. They are subject to natural selection without strong breeding pressure, and they are well adapted to local climatic conditions. The local varieties often display unique traits that have been driven out of the elite varieties in the selection process, and are considered crucial for resistance breeding and the restoration and expansion of the gene pool of cultivated forms [26].
This study shows the presence of spontaneous Mlo resistance in barley landraces (5589, 5590) that were collected in Yemen, in the province Al Bayda, in an area around Al Bayda city (also transliterated as Al-Baidah or Beida, anciently Nashqum), about 200 km south-east of Sanaa. In addition, it was observed that mildew colonies originated from successful infection in the subsidiary cells next to the stomata on the barley epidermis. Only two exceptions were observed, in which the powdery mildew colony originated from a short cell in contact with the stomata. This is in agreement with the observations concerning the origin of colonies on Mlo-resistant plants, made by other investigators [12,13,34].
Controlling of powdery mildew is possible by growing genetically resistant barley cultivars [6,10,16,35]. This is a relatively inexpensive and environmentally safe barley protection measure. It started to be used from the beginning of the application of modern, intensive methods in production. Currently, the powdery mildew of barley is one of the most common and most widespread disease of barley in Europe, causing significant yield losses. However, this disease that is opposite to leaf rust was, for a long time, not important in barley production [35,36].
The genetic diversity of barley landraces offer many traits for barley breeding, especially concerning their resistance to biotic and abiotic stresses [36,37,38]. The genetic heterogeneity within the barley landraces is due to a low level of outcrossing occurring in barley, and farmers mixing the seed of different landraces [39,40,41]. In some studies, more than 50% of tested landraces were found to be a genotypic mixture [42]. However, in some cases, phenotypic diversity does not reflect genetic diversity. For example, this occurs in barleys from Ethiopia, in comparison barleys originating from the Fertile Crescent [43,44].
Yemen is characterized by big contrast in its natural conditions, because of its mountainous topography (Sarat Mountain ranges: Sarat al-Hajaz, Sarat ‘Asir and Sarat al-Yemen) and big contrasts in climate because of the transitional location between the Red Sea, Gulf of Aden, and Arabian Sea on one side, and the Empty Quarter (Rub al Khali—the world’s largest sand desert) on the other side. Because of its very different agro-climatic conditions, the expression of a wide array of genes, and a wide diversity of barley, is allowed. Collection missions in Yemen are recommended, because the landraces of major crops in this country are subject to genetic erosion, due to drought and desertification [23].
The most interesting finding in this study is the presence of spontaneous Mlo resistance in barley landraces (5589, 5590) that were collected in Yemen, in the province Al Bayda. Mlo resistance is associated with a negative pleiotropic effect that is expressed by increased susceptibility to necrotrophic and other pathogens, and lower yielding [36,45,46,47,48,49,50]. For the first time, Mlo resistance was identified in a local variety from Ethiopia [36,50,51]. This natural allele has been designated mlo11. The remaining variants were identified in barley-induced mutants. The Mlo gene encodes a transmembrane protein of unexplained function. Immunity is conditioned by loss-of-function mutants. Literature reports indicate that almost 50 mlo alleles have been identified [51]. All of them, with the exception of mlo11, were produced by mutagenesis [36,51]. The first in Europe was the Mlo-resistant barley variety ‘Atem’ (released in the Netherlands in 1979), which derived its resistance (mlo11) from the Ethiopian landrace L92. Almost all the barley varieties with Mlo resistance have the same allele, mlo11, with an important exception, ‘Alexis’ (mlo9). This proves that, in contrary to the mutants, barley landrace were the most important sources of Mlo resistance [12,14,36,51,52,53].
The presence of mlo resistance genes in barley collected in Yemen should be not be a very big surprise, because it was described previously in Ethiopia. These geographical regions are just separated by the strait Gate of Tears (Bab el Mandeb), which is 27.4 km wide, they are very similar on the agroecological level, and there are many records on the exchange of goods and people across this strait, from ancient times [25,54].
In the presented study, a seedling resistance test was used in order to describe the infection types that were expressed by barley recombinant lines after inoculation with the differentiated isolates of B. graminis f. sp. hordei. This kind of testing is sufficient for disease resistance screening, and is commonly used in breeding programs, to postulate the presence of genes in modern cultivars, and to screen for new sources of effective resistance [16,19,52,53]. However, these kinds of tests are not very useful to identify and describe partial resistance. For a description of this kind of resistance, there is a need to conduct measurements of resistance characteristics, additional to the infection type. Furthermore, partial resistance is generally better expressed at the adult plant stage [55,56,57]. A final determination of the number of resistance genes, and their type of action in the tested hybrid lines, may be established with the use of crosses and backcrosses among appropriate genotypes.

5. Conclusions

The results of this study demonstrate the practical advantages of preserving the genetic diversity of barley in the form of landraces, to control barley powdery mildew by breeding for resistance.
This is the first report about the discovery of spontaneous Mlo resistance in barley landrace originating from Yemen, and in a country other than Ethiopia, Libya, and Turkey [12,15,16,32,58].
Future work will concentrate on the genetic study of Mlo resistance occurring in selections from the landraces 5589 and 5590, and resistance in landrace 5607. This work will include appropriate crosses and/or molecular markers. A pre-breeding effort is also needed, to introduce these alleles into elite cultivars of barley, to create initial materials for European breeding programs. This is a necessary step between the barley gene bank collections and the practical use of barley genetic resources in breeding programs.
In recent years, Mlo resistance has become a very important source of durable powdery mildew resistance in Europe [15,16]. Consequently, the new source of highly effective powdery mildew resistance that is described in this study, should be successfully used in barley breeding programs.

Author Contributions

Conceptualization, J.H.C.; methodology, J.H.C.; formal analysis, J.H.C. and E.C.; investigation, J.H.C.; resources, J.H.C.; writing—original draft preparation, J.H.C. and E.C.; visualization, E.C.; project administration, J.H.C.; funding acquisition, J.H.C. Both authors have read and agreed to the published version of the manuscript.

Funding

The results presented are based on evaluation carried out in the frame of the ECPGR-funded complementary module of the European Union project GENRES PL98-104 on barley genetic resources evaluation.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data are avialable in tables. Contact person is Jerzy H. Czembor, IHAR-PIB Radzików.

Acknowledgments

Authors thank J. Valkoun, J. Konopka and S. Ceccarelli (ICARDA, Aleppo, Syria) for providing seed samples of barley landrace from Yemen, H. J. Schaerer (ETH, Zurich, Switzerland) for the powdery mildew isolates, L. Munk (Royal Agricultural and Veterinary University, Copenhagen, Denmark) for the near-isogenic lines of ‘Pallas’.

Conflicts of Interest

The authors declare no conflict of interest. Authors declare any personal circumstances or interest that may be perceived as inappropriately influencing the representation or interpretation of reported research results. Any role of the funders in the design of the study; in the collection, analyses or interpretation of data; in the writing of the manuscript, or in the decision to publish the results must be declared in this section.

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Table 1. Collection data of 33 landraces collected in Yemen.
Table 1. Collection data of 33 landraces collected in Yemen.
No.ICARDA IGIHAR No.DateLongitudeLatitudeAltitudeProvinceCollection Site
13731353691977.10.--4302-E1506-N0Al HudaydahTurba
23731453701977.19.--4302-E1506-N0Al HudaydahTurba
33731653711977.11.264414-E1524-N2250Sana’aSana’a
4373195372nd *4402-E1335-N1400Ta’izzTa’izz
5373205373nd4414-E1524-N2200Sana’aBani Husshaysh, NE of Sana’a
63852053751980.06.084427-E1423-N2350Dhamar19 km S of Dhamar
73852653761980.06.144405-E1518-N2500Sana’a15 km W from Sana’a
811309654451988.--.--4545-E1452-NndAl Bayda’nd
911322854481988.--.--4430-E1433-NndDhamarnd
103760155891980.05.--4505-E1415-N2500Al Bayda’Al Sharaf, store
113760355901980.05.--4455-E1415-N2560Al Bayda’Agaba
123760955911980.05.--4548-E1415-N1950Al Bayda’Al Soumaa
133761255921980.05.--4345-E1655-N1970Sa’dahAl Mahazer
143761355931980.05.--4405-E1330-N2300Ta’izzJabal Sabir
153761555941980.05.--4405-E1330-N2300Ta’izzJabal Sabir
163762055951980.05.--4410-E1350-N2000IbbShiban
173762355961980.06.--4422-E1418-N2600IbbYarim market
183762555971980.06.--4412-E1352-N2500IbbJabal Al Kadra
193763356011980.06.064348-E1541-N2400Sana’aDharhan
203763956021980.06.084427-E1423-N2350Dhamar19 km S of Dhamar
213764256031980.06.084427-E1425-N2200DhamarDhumara, threshing floor
223764556041980.06.094425-E1433-N2200Dhamar1 km E of Ghamar
233764656051980.06.104426-E1432-N2200Dhamar4 km E of Dhamar
243765156061980.06.104417-E1453-N2200Dhamar10 km N of Ma’bar
253765656071980.06.114401-E1528-N2500Sana’a14 km from Shibam in direction to Sana’a
263766056081980.06.144422-E1343-N2500Ta’izzDar Mutera
273767056091980.06.174415-E1515-N2200Sana’a14 km S of Sana’a
283767356101980.06.204359-E1336-N1400Ta’izzTa’izz market
293851956121980.05.--4345-E1655-N1970Sa’dahAl Mahazer
303852156131980.06.084427-E1425-N2200DhamarDhumara, threshing floor
313852256141980.06.094425-E1433-N2200Dhamar1 km E of Ghamar
323852356151980.06.104417-E1453-N2200Dhamar10 km N of Ma’bar
333852856161980.06.--4359-E1336-N1400Ta’izzTa’izz market
* nd—no data.
Table 2. B. graminis f. sp. hordei isolates used for artificial inoculation and their virulence spectra against resistance genes on differential set of Pallas near-isogenic lines and 11 cultivars.
Table 2. B. graminis f. sp. hordei isolates used for artificial inoculation and their virulence spectra against resistance genes on differential set of Pallas near-isogenic lines and 11 cultivars.
No.Pallas Isolines and CultivarsGeneBgh Isolates
Bgh 1Bgh 2Bgh 3Bgh 4Bgh 8Bgh 9Bgh 11Bgh 13Bgh 14Bgh 24Bgh 28Bgh 29Bgh 31Bgh 33Bgh 36Bgh 40Bgh 48Bgh 51Bgh 57Bgh 63
1P1Mla100444000000400400400
2P2Mla310000000000400440000
3P3Mla6, Mla1400000040404000444444
4P4BMla7, + ?44410224402441441444
5P8BMla940400004040400000040
6P10Mla1200400400400440440404
7P11Mla13, MlRu340400000440040000404
8P12Mla2244044040444440044400
9P13Mla2311212121111211111111
10P14Mlra44404444044444444444
11P15Ml (Ru2)44443424420442444444
12P17Mlk44422224220442422444
13P18Mlnn44444244422444444422
14P19Mlp22222222222222222222
15P20Mlat22242224222222242422
16P22mlo50(4)0(4)0(4)0(4)0(4)0(4)30(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)
17P23Ml (La)44444244444444444444
18P24Mlh44404444444444044444
19TrumphMla7, Ml (Ab)44444444444444444444
20P21Mlg, Ml (CP)44400040404444440404
21PallasMla844444444444444444444
22GunnarMla3, Ml (Tu2)00000000000000000000
23P4AMla7, Mlk, + ?22222222224240222442
24P6Mla7, MlLG244 00212402240420444
25P7Mla9, Mlk40400004000400000040
26P8AMla9, Mlk40400004000400000040
27P9Mla10, MlDu244401404020444400444
28BenedicteMla9,Ml (IM9)00400000400440440404
29LenkaMla13,Ml (Ab)40400000400040000404
30SteffiMl (St1), Ml (St2)22200000400230420204
31KreditMl (Kr)42402002444240422444
32JarekMl (Kr), + ?44444244444444424424
33BorwinaMl (Bw)43304044422344434422
34Manchuria-44444444444444444444
Table 3. Set of barley (H. vulgare L.) landraces originated from Yemen, which revealed resistance to at least one B. graminis f. sp. Hordei isolate after inoculation at the seedling stage.
Table 3. Set of barley (H. vulgare L.) landraces originated from Yemen, which revealed resistance to at least one B. graminis f. sp. Hordei isolate after inoculation at the seedling stage.
No.ICARDA IGIHAR No.Bgh IsolatesPostulated Resistance Gene
Bgh 1Bgh 2Bgh 3Bgh 4Bgh 8Bgh 9Bgh 11Bgh 13Bgh 14Bgh 24Bgh 28Bgh 29Bgh 31Bgh 33Bgh 36Bgh 40Bgh 48Bgh 51Bgh 57Bgh 63
1376015589 1 10(4)0(4)0(4)0(4)0(4)0(4)30(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)mlo
2376035590 1 10(4)0(4)0(4)0(4)0(4)0(4)30(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)0(4)mlo
3-5598 1 1444444444442404444nd2?
4-5598 4 2444444442444224244nd4?
5376465605 1 124444244444442442244?
6376565607 1 100000000004000000000?
7-5611 2 244044044444440044400Mla22
8385285616 1 24440002220244242042nd Mla7, Ml (LG2)
9385285616 3 144400024202440420424Mla7, Ml (LG2)
nd—no data.
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Czembor, J.H.; Czembor, E. Mlo Resistance to Powdery Mildew (Blumeria graminis f. sp. hordei) in Barley Landraces Collected in Yemen. Agronomy 2021, 11, 1582. https://doi.org/10.3390/agronomy11081582

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Czembor JH, Czembor E. Mlo Resistance to Powdery Mildew (Blumeria graminis f. sp. hordei) in Barley Landraces Collected in Yemen. Agronomy. 2021; 11(8):1582. https://doi.org/10.3390/agronomy11081582

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Czembor, Jerzy H., and Elżbieta Czembor. 2021. "Mlo Resistance to Powdery Mildew (Blumeria graminis f. sp. hordei) in Barley Landraces Collected in Yemen" Agronomy 11, no. 8: 1582. https://doi.org/10.3390/agronomy11081582

APA Style

Czembor, J. H., & Czembor, E. (2021). Mlo Resistance to Powdery Mildew (Blumeria graminis f. sp. hordei) in Barley Landraces Collected in Yemen. Agronomy, 11(8), 1582. https://doi.org/10.3390/agronomy11081582

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