ITEMS FROM TURKEY

CIMMYT AND THE MINISTRY OF AGRICULTURE AND RURAL AFFAIRS
P.K. 39 Emek, 06511 Ankara, Turkey.

H.J. Braun, A.R. Hede, J. Nicol, and B. Akin (CIMMYT­Turkey); M. Keser, N. Bolat, N. Colak, H. Ekiz, S. Taner, S. Ceri, F. Partigoc, L. Cetin, S. Albustan, F. E. Donmez, Dusunceli, S. Yazar, I. Ozseven, I. Ozturk, and T. Yildirim (Ministry of Agriculture and Rural Affairs); and M. Mousaad and A. Yahyaoui (ICARDA, Aleppo, Syria).

The International Winter Wheat Program (IWWIP) is a joint program carried out by the Ministry of Agriculture of Turkey, CIMMYT, and ICARDA. The two main objectives of the program are to develop broadly adapted, disease-resistant, high-yielding winter wheat germ plasm for the winter and facultative wheat-growing areas in Central and West Asia and North Africa (CWANA) and to help facilitate germ plasm exchange among the winter wheat-breeding programs around the world.

Of the 103 million ha of wheat grown in the least-developed countries. Approximately 31 x 10^6^ ha are winter and facultative wheat, of which 16.5 x 10^6^ ha are sown in CWANA; 13 x 10^6^ ha in China; and 1 x 10^6^ ha in South America, North Africa, and North Korea. After China, Turkey is the 2nd largest winter wheat grower among the least-developed countries with 6.6 x 10^6^ ha; followed by Iran with 4 x 10^6^ ha.

News on germ plasm development and cultivar releases. [p. 145-146]

Since 1980, 27 cultivars from the IWWIP program have been released in CWANA. In 2002 alone, nine cultivars were released in Afghanistan (1), Georgia (1), Turkey (6), and Uzbekistan (1) (Table 1). Three of these cultivars are targeted for rainfed areas and five for irrigated/supplementary irrigation conditions. Thirty-four cultivars are presently included in registration trials in Armenia (6), Georgia (1), Kazakhstan (2), Kyrghyzstan (7), Tajikistan (6), Turkey (5), Turkmenistan (3), and Uzbekistan (4).

The winter wheat program draws heavily on the winter (W)/spring (S) crosses. A major contribution to the winter wheat program is made through the spring wheat lines developed at CIMMYT­Mexico, which are crossed with winter wheats. Many of the most successful CIMMYT spring wheats were derived from W/S crosses. Now, the same is happening for winter wheat. More than 75 % of the IWWIP lines released or in registration trials are selected from crosses between winter and spring wheat lines and three-way crosses (winter/spring//winter). These WSW-derived cultivars are now making their way into registration trials throughout the CWANA region (Figure 1).

News on germ plasm exchange: the case of yellow rust. [p. 146]

The Facultative and Winter Wheat Observation Nursery (FAWWON) has served as the main vehicle for facilitating germ plasm exchange among winter wheat programs. This nursery consists of lines developed by the IWWIP program and of cultivars submitted by national programs, university programs, or private companies from countries in CWANA, western and eastern Europe, China, South America, and the U.S.A. The 11th FAWWON consisting of 146 entries was distributed for planting in the 2001-02 cropping cycle to around 80 coöperators from more than 40 countries

Yellow rust is one of the most important leaf diseases for the winter wheat areas in west and central Asia. Within the last decade, CWANA countries suffered several major yellow rust epidemics, with losses up to 50 %. Figure 2 shows the maximum yellow rust score from the evaluation of the 11th FAWWON across 10 locations in Iran (5), Turkey (1), Azerbaijan (1), Tajikistan (1), Syria (1), and China (1). Characteristically, most lines developed by the IWWIP program show good levels of resistance, whereas most other lines are highly susceptible to yellow rust. The fact that many yellow rust-susceptible, but otherwise excellent, lines with highly favorable characteristics will be dismissed by breeders due to yellow rust susceptibility and, therefore, not utilized by breeding programs has forced us to think of ways to restructuring the FAWWON nursery. These changes will be implemented within the coming year.

Research on root rots and nematodes. [p. 147-148]

H. Aktas, A. Bagci, N. Bolat, O. Buyuk, C. Cekic, H. Ekiz, I. Gultekin, H. Hekimhan, Y. Kaya, M. Keser, I. Ozseven, M. Tekeoglu, H. Toktay, B. Tunali, A. Tulek, Zafer Uçkun, A.F. Yildirim, and A. Yorgancilar (Turkish Ministry of Agriculture and Rural Affairs); H.J. Braun, M. Mergoum, J. Nicol, R. Trethowan, M. van Ginkel, and M William (CIMMYT International); H. Elekcioglu (Cukurova University); E. Sahin (Osman Gazi University); and R. Rivoal (INRA/ENSAR France).

Since 1998, the Ministry of Agriculture and Rural Affairs in Turkey (MARA) in collaboration with CIMMYT staff based in Turkey have initiated two key National/International projects. One of these is on cereal nematodes and the other on cereal root rots. These projects cover a range of research areas including;

• surveys,
• economic importance and population dynamics,
• identifying of sources of resistance, and
• control methods emphasising plant genetic resistance.

Below is a brief summary of some of our findings to date. We very much encourage anyone interested in collaborating with our program to make contact with us.

Preliminary surveys. These surveys have been conducted on the Central Anatolian Plateau, the major winter wheat-growing region of Turkey. The objective was to understand the distribution of two economically important cereal nematodes, cyst (Heterodera spp.), and lesion (Pratylenchus spp.). Seventy-two percent of the root samples and 83 % of the soil samples contained cysts and in approximately 40 % of soil samples one or both lesion nematodes were found. Cereal cyst nematode was identified to species level using both traditional morphology and a RFLP PCR-based molecular method. None of the samples contained H. avenae, the most common cereal cyst nematode documented. Instead, 40 % of the samples contained H. latipons, 32 % H. filipjevi, and 28 % a mix a both species

A range of Fusarium species have been isolated from cereal crown roots with the most frequently isolated species being F. culmorum, F. nivale, F. psuedograminearum, F. acuminatum, and F. heterosporum.

The taxonomy of cyst nematode is very time consuming and difficult, and work is underway to optimize the molecular technology to identify the different species of Heterodera. We hope in the near future to relate and collate survey data with both classical morphology and molecular methods.

In many cases, several species of nematodes and root rots are present in the same soil, suggesting that we are dealing with a root disease complex and management strategies need to account for this. In addition, zinc deficient soils are widespread and can be considered part of the problem complex (Cakmak et al. 1999).

To understand the economic importance and population dynamics of both nematodes and root rots, multi-location and multi-year yield trials are being conducted. Work with root rots is more advanced than with nematodes. Data from 2-year yield trials with and without root rot inoculation (inoculated as a mix of both Fusarium species and Bipolaris) indicate that most of the common winter wheat cultivars grown in Turkey are intolerant suffering average yield losses of 37 %. Furthermore, preliminary data of only 1 year suggests strongly that sources of spring wheat resistance identified in Australia and confirmed at CIMMYT-Mexico also are resistant and have high tolerance under field conditions in Turkey. We are in the second year of field testing with nematodes in three locations. Preliminary data from last year clearly show economic grain loss, with most common winter wheat cultivars being intolerant and susceptible (i.e., allow nematode multiplication) to both the lesion and cyst nematodes. Detailed knowledge is available about the population dynamics of the lesion nematodes (P. thornei and P. neglectus) and at least one of the species of cyst nematode (H. avenae). However, little is known about the biology and behavior of other Heterodera species that are commonly found in winter wheat areas of the world, namely H. filipjevi and H. latipons. In addition to monitoring field-population dynamics, we also conduct a range of basic biological experiments to identify factors that affect the hatch of the cysts and to understand the duration of the life cycle and the infection process.

Identification of sources of resistance. A major focus of the work is to screen winter wheat and identify sources of resistance to both the key nematodes and root rots. Again, this work is more advanced with root rots than nematodes on winter wheat. Over 100 crosses/year are being made with sources of both nematode and root rot-resistant germ plasm Nicol 2002; Nicol et al. 2001). Spring wheat lines with confirmed root disease resistance also are used in the crossing program.

A large screening program in the south of Turkey near Konya was established where annually around 2,000 accessions are inoculated with a root rot complex. The best accessions form screening nurseries are further tested in replicated screening and yield trials. Resistant lines are confirmed based on field trials and greenhouse work. Screening for nematode resistance concentrates on field screening at present, but work is underway to establish pure nematode cultures in the laboratory and ultimately screen with individual nematodes under controlled laboratory conditions. With cyst nematode, more work is required to understand the biology before such screening can be conducted on a larger scale.

Work within CIMMYT also is utilizing the tools of molecular biology in a MAS strategy. Several markers for known nematode-resistance genes developed in Australia are optimized and are being used routinely on CIMMYT germ plasm. However, given the complexity of the nematode in the region we need to confirm the effectiveness of these known sources of resistance with the range of nematode populations from the region.

Once we have more advanced plant populations (F4/F5) where resistance has been incorporated, we will conduct confirmation screening to validate the incorporation of resistances using both traditional and molecular tools where appropriate. As we produce these root disease resistant wheat lines, they will be distributed through the international nurseries.

Cereal nematodes and root rots can be controlled in several ways. The major emphasis in our program is placed on using plant genetic resistance. Because resistance alone is probably not the complete answer (as many resistances are partial), other methods need to be investigated. To control root rots, we will look at the effects of seed treatment with fungicides, application of microelements (including B, Cu, Fe, Mn, S, and Zn), seed-sowing density, and rotation experiments of cereals with other non-cereal crops (such as canola and sugar beet). With nematodes, we will look at the effect of crop rotation and management practices (such a conservation tillage and cultivation) on nematode numbers. As has been proven in the U.S. and Australia, there is no doubt that agronomic practices have a key role to play in the control of these pathogens.

Progress to date on breeding for root rot resistance and tolerance. [p. 148-149]

Extensive field screening over the last 3 years has assessed the resistance of winter wheat germ plasm against root rots under field conditions. Resistance is defined as a reduction in symptom development of the disease. In Cumra, 40 km south of Konya, field-observation plots were assessed by inoculating seed with a combination of root rot species (Fusarium and Bipolaris) and comparing symptom development against uninoculated plots. These lines are now entering yield trials to assess tolerance (yield loss) and also have been extensively crossed in the IWWIP program. The best entries after 3-year screening are shown in Table 2. Several of the identified lines are widely grown cultivars such as Gerek 79, Dagdas, and Katia-1.

Training. The IWWIP program is training Turkish scientists and scientists from the region in the field of soil disease cereal research. This includes postgraduate training and special courses such as the one planned for June 2003 in Turkey. Several Australian pathologists will attend this course to provide their expertise and knowledge. The training course is called 'Soil Borne Pathogens of Cereals' and will be from 14-28 June under the coördination of the IWWIP. Participants will be trained to work with both nematodes and root rots. We are very grateful to the sponsors, principally led by the ATSE Crawford Fund, CIMMYT, MARA, ICARDA, GRDC, ACIAR, and the Kirkhouse Trust.

Concluding remarks. We believe by conducting this highly focused, complex and difficult research we can clearly define the soilborne constraints in the winter wheat regions of CWANA and ultimately significantly improve wheat production and sustainability of the cropping systems in our region. The key to this will involve a breeding approach to produce high-yielding, quality-adapted germ plasm combined with multiple root disease resistances and microelement efficiencies, complimented with appropriate management practices. This work is large and encompassing, and we welcome any collaboration from interested parties.

Publications. [p. 149]

• Nicol JM. 2002. Important Nematode Pests of Cereals. In: Bread Wheat Production and Improvement, FAO Plant Production and Protection Series, FAO, Rome, Italy. Pp. 345-366.
• Nicol JM, Rivoal R, Bolat N, Aktas H, Braun HJ, Mergoum M, Yildrim AF, Bagci A, Eleckcioglu H, and Yahyaoui, A. 2002. The frequency and diversity of the cyst and lesion nematode on wheat in the Turkish Central Anatolian Plateau. Nematology 4(2):272.
• Nicol JM, Rivoal R, Trethowan RM, van Ginkel M, Mergoum M, and Singh RP. 2001. CIMMYT's approach to identify and use resistance to nematodes and soil-borne fungi, in developing superior wheat germplasm. In: Wheat in a Global Environment (Bedö Z and Láng L eds.). Kluwer Academic Publishers, Netherlands. Pp. 381-389.